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--- elearning:workbooks:centos:8:admin:l119 [2022/02/22 15:15] – admin
+++ elearning:workbooks:centos:8:admin:l119 [2022/06/05 17:58] (Version actuelle) – created admin
@@ Ligne 3: / Ligne 3: @@
 Version : **2022.01**
-Updated: ~~LASTMOD~~
+Updated : ~~LASTMOD~~
-======LCE601 - Managing Integrated Peripherals======
+======LCE513 - Managing the Network======
 =====Contents=====
-  * **LCE601 - Managing Integrated Peripherals**
+  * **LCE513 - Managing the Network**
     * Contents
-    * Special Files
+    * Presentation
-    * LAB #1 - Commands
+      * The nmcli Command
-      * 1.1 - The lspci Command
+    * LAB #1 - Configuring the Network
-      * 1.2 - The lsusb Command
+      * 1.1 - Connections and Profils
-      * 1.3 - The dmidecode Command
+      * 1.2 - Name Resolution
-    * LAB #2 - The sysctl Command
+      * 1.3 - Adding a Second IP Address to a Profile
-      * 2.1 - The /proc Directory
+      * 1.4 - The hostname Command
-        * Files
+      * 1.5 - The ip Command
-          * /proc/cpuinfo
+      * 1.6 - Manually Activating and Disactivating a Device
-          * /proc/interrupts
+      * 1.7 - Static Routing
-          * /proc/dma
+        * The ip Command
-          * /proc/ioports
+        * Disactivating/Activating Internal Routing on a Server
-          * /proc/devices
+    * LAB #2 - Diagnostics
-          * /proc/module
+      * 2.1 - The ping Command
-          * /proc/diskstats
+      * 2.2 - The netstat Command
-          * /proc/partitions
+      * 2.3 - The traceroute Command
-          * /proc/swaps
+    * LAB #3 - SSH
-          * /proc/loadavg
+      * 3.1 - Presentation
-          * /proc/meminfo
+        * SSH-1
-          * /proc/version
+        * SSH-2
-        * Directories
+      * 3.2 - Configuring the Server
-          * ide/scsi
+      * 3.3 - Configuring the Client
-          * acpi
+      * 3.4 - SCP
-          * bus
+        * Presentation
-          * net
+        * Usage
-          * sys
+      * 3.5 - Authentication with Asymetric Keys
-      * 2.2 - Using the sysctl Command
-    * LAB #3 - Interpreting Information in /proc
-      * 3.1 - free
-      * 3.2 - uptime ou w
-      * 3.3 - iostat
-      * 3.4 - hdparm
-      * 3.5 - vmstat
-      * 3.6 - mpstat
-      * 3.7 - sar
-    * USB Modules
-    * udev
-      * The udevadm Command
-    * The /sys Filesystem
-    * LAB #4 - Limiting Ressources
-      * 4.1 - ulimit
-      * 4.2 - CGroups
-        * Limiting Memeory Usage
-        * The cgcreate Command
-        * The cgdelete Command
-        * The /etc/cgconfig.conf File
-        * The cgconfigparser Command
-=====Special Files=====
+=====Presentation=====
-In a PC, peripherals are connected to a **controler** which communicates with the processor via a **bus**. The controller and associated peripherals require specific drivers. Under Linux, these drivers are normally supplied as kernel **modules**. Each peripheral is represented by a special file in the **/dev** directory. Each special file contains the information required by the system in order for it to use the driver.
+RHEL/CentOS 8 uses **Network Manager** to manage the network. Network Manager is composed of two things:
+  * a service that manages the connections and reports on their status,
+  * front-ends that use an API to configure the service.
 <WRAP center round important 60%>
-Peripherals that require the system to be halted prior to plugging or unplugging them are refered to as **Cold Plug Devices**. Peripherals that can be plugged/unplugged whilst the system is running are refered to as **Hot Plug Devices**.
+**Important** : Note that IPv6 is activated by default.
 </WRAP>
-The following output shows the typical content of the /dev directory:
+Start by checking the status of the service:
 <code>
-[root@centos8 ~]# ls -l /dev | more
+[root@centos8 ~]# systemctl status NetworkManager.service
-total 0
+● NetworkManager.service - Network Manager
-crw-r--r--.  1 root root     10, 235 Jun 28 02:04 autofs
+   Loaded: loaded (/usr/lib/systemd/system/NetworkManager.service; enabled; vendor pr>
-drwxr-xr-x.  2 root root         180 Jun 28 02:04 block
+   Active: active (running) since Thu 2021-07-22 05:05:29 EDT; 1 months 7 days ago
-drwxr-xr-x.  2 root root         100 Jun 28 02:04 bsg
+     Docs: man:NetworkManager(8)
-drwxr-xr-x.  3 root root          60 Jun 28 02:04 bus
+ Main PID: 1002 (NetworkManager)
-lrwxrwxrwx.  1 root root           3 Jun 28 02:04 cdrom -> sr0
+    Tasks: 3 (limit: 23535)
-drwxr-xr-x.  2 root root        2940 Jun 28 02:04 char
+   Memory: 6.8M
-drwxr-xr-x.  2 root root          80 Jun 28 02:04 cl_centos8
+   CGroup: /system.slice/NetworkManager.service
-crw-------.  1 root root      5,   1 Jun 28 02:04 console
+           └─1002 /usr/sbin/NetworkManager --no-daemon
-lrwxrwxrwx.  1 root root          11 Jun 28 02:04 core -> /proc/kcore
-drwxr-xr-x. 10 root root         200 Jun 28 02:04 cpu
-crw-------.  1 root root     10,  62 Jun 28 02:04 cpu_dma_latency
-drwxr-xr-x.  6 root root         120 Jun 28 02:04 disk
-brw-rw----.  1 root disk    253,   0 Jun 28 02:04 dm-0
-brw-rw----.  1 root disk    253,   1 Jun 28 02:04 dm-1
-drwxr-xr-x.  3 root root          80 Jun 28 02:04 dri
-crw-rw----.  1 root video    29,   0 Jun 28 02:04 fb0
-lrwxrwxrwx.  1 root root          13 Jun 28 02:04 fd -> /proc/self/fd
-crw-rw-rw-.  1 root root      1,   7 Jun 28 02:04 full
-crw-rw-rw-.  1 root root     10, 229 Jun 28 02:04 fuse
-crw-------.  1 root root    245,   0 Jun 28 02:04 hidraw0
-crw-------.  1 root root     10, 228 Jun 28 02:04 hpet
-drwxr-xr-x.  3 root root           0 Jun 28 02:04 hugepages
-crw-------.  1 root root     10, 183 Jun 28 02:04 hwrng
-lrwxrwxrwx.  1 root root          12 Jun 28 02:04 initctl -> /run/initctl
-drwxr-xr-x.  4 root root         280 Jun 28 02:04 input
-crw-r--r--.  1 root root      1,  11 Jun 28 02:04 kmsg
-lrwxrwxrwx.  1 root root          28 Jun 28 02:04 log -> /run/systemd/journal/dev-log
-crw-rw----.  1 root disk     10, 237 Jun 28 02:04 loop-control
-crw-rw----.  1 root lp        6,   0 Jun 28 02:04 lp0
-crw-rw----.  1 root lp        6,   1 Jun 28 02:04 lp1
-crw-rw----.  1 root lp        6,   2 Jun 28 02:04 lp2
-crw-rw----.  1 root lp        6,   3 Jun 28 02:04 lp3
-drwxr-xr-x.  2 root root         100 Jun 28 02:04 mapper
-crw-------.  1 root root     10, 227 Jun 28 02:04 mcelog
-crw-r-----.  1 root kmem      1,   1 Jun 28 02:04 mem
-drwxrwxrwt.  2 root root          40 Jun 28 02:04 mqueue
-drwxr-xr-x.  2 root root          60 Jun 28 02:04 net
-crw-rw-rw-.  1 root root      1,   3 Jun 28 02:04 null
---More--
-</code>
-As you can see, certain files refer to **block** devices whilst others refer to **character** devices:
+Warning: Journal has been rotated since unit was started. Log output is incomplete or>
+lines 1-11/11 (END)
-<code>
+[^q] <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<Type CONTROL Q
-...
-brw-rw----.  1 root disk      8,   1 Jun 28 02:04 sda1
-...
-crw-rw-rw-.  1 root tty       5,   0 Jun 28 02:04 tty
-...
 </code>
-The major difference between these two types lies in the way that the communication between the system and the peripheral takes place. In the case of a block file, that communication uses a buffer whilst in the case of a character file the communication takes place directly byte by byte.
+===The nmcli Command===
-The figures that can be seen immediately before the date of the special file are called respectively the **major** and the **minor** :
+The Network Manager Command Line Interface or **nmcli** is used to configure NetworkManager.
-  * the **major** identifies the peripheral's driver,
+The command line switches of the nmcli command are:
-  * the **minor** identifies the peripheral. For instance 8,1 indicates the first partition of the **sda** disk.
-=====LAB #1 - Commands=====
-====1.1 - The lspci Command====
-This command show a list of the peripherals connected to the PCI, AGP and PCI express buses:
 <code>
-[root@centos8 ~]# lspci
+[root@centos8 ~]# nmcli help
-:00.0 Host bridge: Intel Corporation 440FX - 82441FX PMC [Natoma] (rev 02)
+Usage: nmcli [OPTIONS] OBJECT { COMMAND | help }
-:01.0 ISA bridge: Intel Corporation 82371SB PIIX3 ISA [Natoma/Triton II]
-:01.1 IDE interface: Intel Corporation 82371SB PIIX3 IDE [Natoma/Triton II]
-:01.2 USB controller: Intel Corporation 82371SB PIIX3 USB [Natoma/Triton II] (rev 01)
-:01.3 Bridge: Intel Corporation 82371AB/EB/MB PIIX4 ACPI (rev 03)
-:02.0 VGA compatible controller: Device 1234:1111 (rev 02)
-:03.0 Unclassified device [00ff]: Red Hat, Inc. Virtio memory balloon
-:07.0 SATA controller: Intel Corporation 82801IR/IO/IH (ICH9R/DO/DH) 6 port SATA Controller [AHCI mode] (rev 02)
-:12.0 Ethernet controller: Red Hat, Inc. Virtio network device
-:1e.0 PCI bridge: Red Hat, Inc. QEMU PCI-PCI bridge
-:1f.0 PCI bridge: Red Hat, Inc. QEMU PCI-PCI bridge
-</code>
-To obtain peripheral specific information, use the **-v** or **-vv** switches whilst specifying the peripheral ID:
+OPTIONS
+  -a, --ask                                ask for missing parameters
+  -c, --colors auto|yes|no                 whether to use colors in output
+  -e, --escape yes|no                      escape columns separators in values
+  -f, --fields <field,...>|all|common      specify fields to output
+  -g, --get-values <field,...>|all|common  shortcut for -m tabular -t -f
+  -h, --help                               print this help
+  -m, --mode tabular|multiline             output mode
+  -o, --overview                           overview mode
+  -p, --pretty                             pretty output
+  -s, --show-secrets                       allow displaying passwords
+  -t, --terse                              terse output
+  -v, --version                            show program version
+  -w, --wait <seconds>                     set timeout waiting for finishing operations
-<code>
+OBJECT
-[root@centos8 ~]# lspci -v -s 00:03.0
+  g[eneral]       NetworkManager's general status and operations
-:03.0 Unclassified device [00ff]: Red Hat, Inc. Virtio memory balloon
+  n[etworking]    overall networking control
-        Subsystem: Red Hat, Inc. Device 0005
+  r[adio]         NetworkManager radio switches
-        Physical Slot: 3
+  c[onnection]    NetworkManager's connections
-        Flags: bus master, fast devsel, latency 0, IRQ 10
+  d[evice]        devices managed by NetworkManager
-        I/O ports at e000 [size=64]
+  a[gent]         NetworkManager secret agent or polkit agent
-        Memory at fe400000 (64-bit, prefetchable) [size=16K]
+  m[onitor]       monitor NetworkManager changes
-        Capabilities: [84] Vendor Specific Information: VirtIO: <unknown>
-        Capabilities: [70] Vendor Specific Information: VirtIO: Notify
-        Capabilities: [60] Vendor Specific Information: VirtIO: DeviceCfg
-        Capabilities: [50] Vendor Specific Information: VirtIO: ISR
-        Capabilities: [40] Vendor Specific Information: VirtIO: CommonCfg
-        Kernel driver in use: virtio-pci
 </code>
-<code>
+=====LAB #1 - Configuring the Network=====
-[root@centos8 ~]# lspci -vv -s 00:03.0
-:03.0 Unclassified device [00ff]: Red Hat, Inc. Virtio memory balloon
-        Subsystem: Red Hat, Inc. Device 0005
-        Physical Slot: 3
-        Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR+ FastB2B- DisINTx-
-        Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
-        Latency: 0
-        Interrupt: pin A routed to IRQ 10
-        Region 0: I/O ports at e000 [size=64]
-        Region 4: Memory at fe400000 (64-bit, prefetchable) [size=16K]
-        Capabilities: [84] Vendor Specific Information: VirtIO: <unknown>
-                BAR=0 offset=00000000 size=00000000
-        Capabilities: [70] Vendor Specific Information: VirtIO: Notify
-                BAR=4 offset=00003000 size=00001000 multiplier=00000004
-        Capabilities: [60] Vendor Specific Information: VirtIO: DeviceCfg
-                BAR=4 offset=00002000 size=00001000
-        Capabilities: [50] Vendor Specific Information: VirtIO: ISR
-                BAR=4 offset=00001000 size=00001000
-        Capabilities: [40] Vendor Specific Information: VirtIO: CommonCfg
-                BAR=4 offset=00000000 size=00001000
-        Kernel driver in use: virtio-pci
-</code>
-===Command Line Switches===
+====1.1 - Connections and Profiles====
-The command line switches of this command are:
+NetworkManager uses **connections** and **profiles** that allow for different configurations of the same interface or **device**. To see the current connections, use the following command:
 <code>
-[root@centos8 ~]# lspci --help
+[root@centos8 ~]# nmcli c show
-lspci: invalid option -- '-'
+NAME    UUID                                  TYPE      DEVICE
-Usage: lspci [<switches>]
+ens18   fc4a4d23-b15e-47a7-bcfa-b2e08f49553e  ethernet  ens18
+virbr0  03f6c432-2a09-47e7-9693-208431a572ee  bridge    virbr0
-Basic display modes:
--mm             Produce machine-readable output (single -m for an obsolete format)
--t              Show bus tree
-Display options:
--v              Be verbose (-vv or -vvv for higher verbosity)
--k              Show kernel drivers handling each device
--x              Show hex-dump of the standard part of the config space
--xxx            Show hex-dump of the whole config space (dangerous; root only)
--xxxx           Show hex-dump of the 4096-byte extended config space (root only)
--b              Bus-centric view (addresses and IRQ's as seen by the bus)
--D              Always show domain numbers
--P              Display bridge path in addition to bus and device number
--PP             Display bus path in addition to bus and device number
-Resolving of device ID's to names:
--n              Show numeric ID's
--nn             Show both textual and numeric ID's (names & numbers)
--q              Query the PCI ID database for unknown ID's via DNS
--qq             As above, but re-query locally cached entries
--Q              Query the PCI ID database for all ID's via DNS
-Selection of devices:
--s [[[[<domain>]:]<bus>]:][<slot>][.[<func>]]   Show only devices in selected slots
--d [<vendor>]:[<device>][:<class>]              Show only devices with specified ID's
-Other options:
--i <file>       Use specified ID database instead of /usr/share/hwdata/pci.ids
--p <file>       Look up kernel modules in a given file instead of default modules.pcimap
--M              Enable `bus
 </code>
-====1.2 - The lsusb Command====
+Now create another profile attached to **ens18** :
-This command show a list of the peripherals connected to the USB bus:
 <code>
-[root@centos8 ~]# lsusb
+[root@centos8 ~]# nmcli connection add con-name ip_fixed ifname ens18 type ethernet ip4 10.0.2.46/24 gw4 10.0.2.1
-Bus 001 Device 002: ID 0627:0001 Adomax Technology Co., Ltd
+Connection 'ip_fixed' (0f48c74d-5d16-4c37-8220-24644507b589) successfully added.
-Bus 001 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
-[root@centos8 ~]# lsusb -vt
-/:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=uhci_hcd/2p, 12M
-    |__ Port 1: Dev 2, If 0, Class=Human Interface Device, Driver=usbhid, 12M
 </code>
-===Command Line Switches===
+Check that it is visible:
-The command line switches of this command are:
 <code>
-[root@centos8 ~]# lsusb --help
+[root@centos8 ~]# nmcli c show
-Usage: lsusb [options]...
+NAME     UUID                                  TYPE      DEVICE
-List USB devices
+ens18    fc4a4d23-b15e-47a7-bcfa-b2e08f49553e  ethernet  ens18
-  -v, --verbose
+virbr0   03f6c432-2a09-47e7-9693-208431a572ee  bridge    virbr0
-      Increase verbosity (show descriptors)
+ip_fixed 0f48c74d-5d16-4c37-8220-24644507b589  ethernet  --
-  -s [[bus]:][devnum]
-      Show only devices with specified device and/or
-      bus numbers (in decimal)
-  -d vendor:[product]
-      Show only devices with the specified vendor and
-      product ID numbers (in hexadecimal)
-		.LAB#1
-  -D device
-      Selects which device lsusb will examine
-  -t, --tree
-      Dump the physical USB device hierarchy as a tree
-  -V, --version
-      Show version of program
-  -h, --help
-      Show usage and help
 </code>
-====1.3 - The dmidecode Command====
+Note that the output does not show that the **ip_fixed** profile is associated with **ens18** device because it has not yet been activated:
-The **dmidecode** Command reads the **DMI** (//Desktop Management Interface//) table, also called the **SMBIOS** (//System Management BIOS//) and provides information on:
-  * the current status of each peripheral,
-  * possible extensions.
 <code>
-[root@centos8 ~]# dmidecode
+[root@centos8 ~]# nmcli d show
-# dmidecode 3.2
+GENERAL.DEVICE:                         ens18
-Getting SMBIOS data from sysfs.
+GENERAL.TYPE:                           ethernet
-SMBIOS 2.8 present.
+GENERAL.HWADDR:                         4E:B1:31:BD:5D:B2
-structures occupying 511 bytes.
+GENERAL.MTU:                            1500
-Table at 0x000F5870.
+GENERAL.STATE:                          100 (connected)
+GENERAL.CONNECTION:                     ens18
+GENERAL.CON-PATH:                       /org/freedesktop/NetworkManager/ActiveConnect>
+WIRED-PROPERTIES.CARRIER:               on
+IP4.ADDRESS[1]:                         10.0.2.45/24
+IP4.GATEWAY:                            10.0.2.1
+IP4.ROUTE[1]:                           dst = 10.0.2.0/24, nh = 0.0.0.0, mt = 100
+IP4.ROUTE[2]:                           dst = 0.0.0.0/0, nh = 10.0.2.1, mt = 100
+IP4.DNS[1]:                             8.8.8.8
+IP6.ADDRESS[1]:                         fe80::86b6:8d39:cab2:d84d/64
+IP6.GATEWAY:                            --
+IP6.ROUTE[1]:                           dst = fe80::/64, nh = ::, mt = 100
+IP6.ROUTE[2]:                           dst = ff00::/8, nh = ::, mt = 256, table=255
-Handle 0x0000, DMI type 0, 24 bytes
+GENERAL.DEVICE:                         virbr0
-BIOS Information
+GENERAL.TYPE:                           bridge
-        Vendor: SeaBIOS
+GENERAL.HWADDR:                         52:54:00:79:02:66
-        Version: rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org
+GENERAL.MTU:                            1500
-        Release Date: 04/01/2014
+GENERAL.STATE:                          100 (connected (externally))
-        Address: 0xE8000
+GENERAL.CONNECTION:                     virbr0
-        Runtime Size: 96 kB
+GENERAL.CON-PATH:                       /org/freedesktop/NetworkManager/ActiveConnect>
-        ROM Size: 64 kB
+IP4.ADDRESS[1]:                         192.168.122.1/24
-        Characteristics:
+IP4.GATEWAY:                            --
-                BIOS characteristics not supported
+IP4.ROUTE[1]:                           dst = 192.168.122.0/24, nh = 0.0.0.0, mt = 0
-                Targeted content distribution is supported
+IP6.GATEWAY:                            --
-        BIOS Revision: 0.0
-Handle 0x0100, DMI type 1, 27 bytes
+GENERAL.DEVICE:                         lo
-System Information
+GENERAL.TYPE:                           loopback
-        Manufacturer: QEMU
+GENERAL.HWADDR:                         00:00:00:00:00:00
-        Product Name: Standard PC (i440FX + PIIX, 1996)
+GENERAL.MTU:                            65536
-        Version: pc-i440fx-5.2
+GENERAL.STATE:                          10 (unmanaged)
-        Serial Number: Not Specified
+GENERAL.CONNECTION:                     --
-        UUID: 95bd69e3-4a74-44a7-b58c-b74fbfb86df2
+GENERAL.CON-PATH:                       --
-        Wake-up Type: Power Switch
+IP4.ADDRESS[1]:                         127.0.0.1/8
-        SKU Number: Not Specified
+IP4.GATEWAY:                            --
-        Family: Not Specified
+IP6.ADDRESS[1]:                         ::1/128
+IP6.GATEWAY:                            --
+IP6.ROUTE[1]:                           dst = ::1/128, nh = ::, mt = 256
-Handle 0x0300, DMI type 3, 22 bytes
+GENERAL.DEVICE:                         virbr0-nic
-Chassis Information
+GENERAL.TYPE:                           tun
-        Manufacturer: QEMU
+GENERAL.HWADDR:                         52:54:00:79:02:66
-        Type: Other
+GENERAL.MTU:                            1500
-        Lock: Not Present
+GENERAL.STATE:                          10 (unmanaged)
-        Version: pc-i440fx-5.2
+GENERAL.CONNECTION:                     --
-        Serial Number: Not Specified
+GENERAL.CON-PATH:                       --
-        Asset Tag: Not Specified
+lines 28-50/50 (END)
-        Boot-up State: Safe
+[q]
-        Power Supply State: Safe
+</code>
-        Thermal State: Safe
-        Security Status: Unknown
-        OEM Information: 0x00000000
-        Height: Unspecified
-        Number Of Power Cords: Unspecified
-        Contained Elements: 0
-        SKU Number: Not Specified
-Handle 0x0400, DMI type 4, 42 bytes
+To activate the ip_fixed profile, use the following command:
-Processor Information
-        Socket Designation: CPU 0
-        Type: Central Processor
-        Family: Other
-        Manufacturer: QEMU
-        ID: 61 0F 00 00 FF FB 8B 07
-        Version: pc-i440fx-5.2
-        Voltage: Unknown
-        External Clock: Unknown
-        Max Speed: 2000 MHz
-        Current Speed: 2000 MHz
-        Status: Populated, Enabled
-        Upgrade: Other
-        L1 Cache Handle: Not Provided
-        L2 Cache Handle: Not Provided
-        L3 Cache Handle: Not Provided
-        Serial Number: Not Specified
-        Asset Tag: Not Specified
-        Part Number: Not Specified
-        Core Count: 4
-        Core Enabled: 4
-        Thread Count: 1
-        Characteristics: None
-Handle 0x0401, DMI type 4, 42 bytes
+<code>
-Processor Information
+[root@centos8 ~]# nmcli connection up ip_fixed
-        Socket Designation: CPU 1
-        Type: Central Processor
-        Family: Other
-        Manufacturer: QEMU
-        ID: 61 0F 00 00 FF FB 8B 07
-        Version: pc-i440fx-5.2
-        Voltage: Unknown
-        External Clock: Unknown
-        Max Speed: 2000 MHz
-        Current Speed: 2000 MHz
-        Status: Populated, Enabled
-        Upgrade: Other
-        L1 Cache Handle: Not Provided
-        L2 Cache Handle: Not Provided
-        L3 Cache Handle: Not Provided
-        Serial Number: Not Specified
-        Asset Tag: Not Specified
-        Part Number: Not Specified
-        Core Count: 4
-        Core Enabled: 4
-        Thread Count: 1
-        Characteristics: None
-Handle 0x1000, DMI type 16, 23 bytes
+</code>
-Physical Memory Array
-        Location: Other
-        Use: System Memory
-        Error Correction Type: Multi-bit ECC
-        Maximum Capacity: 4 GB
-        Error Information Handle: Not Provided
-        Number Of Devices: 1
-Handle 0x1100, DMI type 17, 40 bytes
+Note that because of the IP address change, your terminal is now blocked.
-Memory Device
-        Array Handle: 0x1000
-        Error Information Handle: Not Provided
-        Total Width: Unknown
-        Data Width: Unknown
-        Size: 4 GB
-        Form Factor: DIMM
-        Set: None
-        Locator: DIMM 0
-        Bank Locator: Not Specified
-        Type: RAM
-        Type Detail: Other
-        Speed: Unknown
-        Manufacturer: QEMU
-        Serial Number: Not Specified
-        Asset Tag: Not Specified
-        Part Number: Not Specified
-        Rank: Unknown
-        Configured Memory Speed: Unknown
-        Minimum Voltage: Unknown
-        Maximum Voltage: Unknown
-        Configured Voltage: Unknown
-Handle 0x1300, DMI type 19, 31 bytes
+<WRAP center round todo 60%>
-Memory Array Mapped Address
+**To do** - Reconnect to the VM using the **CentOS8_SSH_10.0.2.46** connection.
-        Starting Address: 0x00000000000
+</WRAP>
-        Ending Address: 0x000BFFFFFFF
-        Range Size: 3 GB
-        Physical Array Handle: 0x1000
-        Partition Width: 1
-Handle 0x1301, DMI type 19, 31 bytes
+The ip_fixed is now activated and the enp0s3 has been disactivated:
-Memory Array Mapped Address
-        Starting Address: 0x00100000000
-        Ending Address: 0x0013FFFFFFF
-        Range Size: 1 GB
-        Physical Array Handle: 0x1000
-        Partition Width: 1
-Handle 0x2000, DMI type 32, 11 bytes
-System Boot Information
-        Status: No errors detected
-Handle 0x7F00, DMI type 127, 4 bytes
-End Of Table
-</code>
-===Command Line Switches===
-The command line switches of this command are:
 <code>
-[root@centos7 ~]# dmidecode --help
+[root@centos8 ~]# nmcli c show
-Usage: dmidecode [OPTIONS]
+NAME     UUID                                  TYPE      DEVICE
-Options are:
+ip_fixed 0f48c74d-5d16-4c37-8220-24644507b589  ethernet  ens18
- -d, --dev-mem FILE     Read memory from device FILE (default: /dev/mem)
+virbr0   03f6c432-2a09-47e7-9693-208431a572ee  bridge    virbr0
- -h, --help             Display this help text and exit
+ens18    fc4a4d23-b15e-47a7-bcfa-b2e08f49553e  ethernet  --
- -q, --quiet            Less verbose output
- -s, --string KEYWORD   Only display the value of the given DMI string
+[root@centos8 ~]# nmcli d show
- -t, --type TYPE        Only display the entries of given type
+GENERAL.DEVICE:                         ens18
- -u, --dump             Do not decode the entries
+GENERAL.TYPE:                           ethernet
-     --dump-bin FILE    Dump the DMI data to a binary file
+GENERAL.HWADDR:                         4E:B1:31:BD:5D:B2
-     --from-dump FILE   Read the DMI data from a binary file
+GENERAL.MTU:                            1500
- -V, --version          Display the version and exit
+GENERAL.STATE:                          100 (connected)
-</code>
+GENERAL.CONNECTION:                     ip_fixed
+GENERAL.CON-PATH:                       /org/freedesktop/NetworkManager/ActiveConnect>
+WIRED-PROPERTIES.CARRIER:               on
+IP4.ADDRESS[1]:                         10.0.2.46/24
+IP4.GATEWAY:                            10.0.2.1
+IP4.ROUTE[1]:                           dst = 10.0.2.0/24, nh = 0.0.0.0, mt = 100
+IP4.ROUTE[2]:                           dst = 0.0.0.0/0, nh = 10.0.2.1, mt = 100
+IP6.ADDRESS[1]:                         fe80::5223:aee1:998e:9f27/64
+IP6.GATEWAY:                            --
+IP6.ROUTE[1]:                           dst = fe80::/64, nh = ::, mt = 100
+IP6.ROUTE[2]:                           dst = ff00::/8, nh = ::, mt = 256, table=255
-=====LAB #2 - The sysctl Command=====
+GENERAL.DEVICE:                         virbr0
+GENERAL.TYPE:                           bridge
+GENERAL.HWADDR:                         52:54:00:79:02:66
+GENERAL.MTU:                            1500
+GENERAL.STATE:                          100 (connected (externally))
+GENERAL.CONNECTION:                     virbr0
+GENERAL.CON-PATH:                       /org/freedesktop/NetworkManager/ActiveConnect>
+IP4.ADDRESS[1]:                         192.168.122.1/24
+IP4.GATEWAY:                            --
+IP4.ROUTE[1]:                           dst = 192.168.122.0/24, nh = 0.0.0.0, mt = 0
+IP6.GATEWAY:                            --
-====2.1 - The /proc Directory====
+GENERAL.DEVICE:                         lo
+GENERAL.TYPE:                           loopback
+GENERAL.HWADDR:                         00:00:00:00:00:00
+GENERAL.MTU:                            65536
+GENERAL.STATE:                          10 (unmanaged)
+GENERAL.CONNECTION:                     --
+GENERAL.CON-PATH:                       --
+IP4.ADDRESS[1]:                         127.0.0.1/8
+IP4.GATEWAY:                            --
+IP6.ADDRESS[1]:                         ::1/128
+IP6.GATEWAY:                            --
+IP6.ROUTE[1]:                           dst = ::1/128, nh = ::, mt = 256
-The /proc directory contains virtual files and directories wich are created dynamically when consulted. Only root can consult all of the information in /proc.
+GENERAL.DEVICE:                         virbr0-nic
+GENERAL.TYPE:                           tun
-<code>
+GENERAL.HWADDR:                         52:54:00:79:02:66
-[root@centos8 ~]# ls /proc
+GENERAL.MTU:                            1500
-      16391  19    2212  2427  2622  431   59    84    999          mdstat
+GENERAL.STATE:                          10 (unmanaged)
-     16476  1931  2215  2428  2659  432   6     842   acpi         meminfo
+GENERAL.CONNECTION:                     --
-   16534  1956  2222  2431  2667  433   60    8465  buddyinfo    misc
+GENERAL.CON-PATH:                       --
-     16576  1960  2226  2432  2686  434   61    866   bus          modules
+lines 27-49/49 (END)
-  16593  2     2230  2435  27    435   63    867   cgroups      mounts
+[q]
-     16598  20    2237  2439  28    436   64    868   cmdline      mtrr
-   16600  2007  2238  244   29    437   65    869   consoles     net
-   16613  2029  2241  2443  3     44    6568  87    cpuinfo      pagetypeinfo
-   16646  203   2244  2445  31    446   66    870   crypto       partitions
-   16673  2034  2247  2449  32    45    67    871   devices      sched_debug
-   16677  2037  2260  2451  33    46    674   872   diskstats    schedstat
-   16711  2054  2262  2465  34    47    68    874   dma          scsi
-     16712  2062  2267  2472  35    4790  69    875   driver       self
-   16729  21    2268  2473  37    49    70    878   execdomains  slabinfo
-   16742  210   2274  2474  38    50    701   879   fb           softirqs
-   17     2118  2275  2475  39    5076  71    880   filesystems  stat
-     1764   2121  2280  2476  4     51    714   884   fs           swaps
-   180    2124  2287  2478  40    52    72    887   interrupts   sys
-   181    2126  2292  2481  402   53    73    9     iomem        sysrq-trigger
-   1817   2156  23    2484  41    532   74    901   ioports      sysvipc
-   182    2160  2302  25    419   539   75    903   irq          thread-self
-  1828   2164  2307  2536  420   55    76    9144  kallsyms     timer_list
-     1829   2165  2310  2539  421   568   8     916   kcore        tty
-  183    2167  2330  2571  422   569   808   918   keys         uptime
-   1845   2169  2332  2578  423   570   809   919   key-users    version
-   185    2177  2349  2579  425   571   81    921   kmsg         vmallocinfo
-  186    2187  2358  259   426   572   833   969   kpagecgroup  vmstat
-  187    2190  2373  2593  427   573   835   986   kpagecount   zoneinfo
-     1880   2194  2384  26    428   574   837   989   kpageflags
-  1883   22    239   2602  43    575   838   990   loadavg
-  1888   2204  241   2608  430   576   839   993   locks
 </code>
-===Files===
+To see the characteristics of **ens18** connection, use the following command:
-==/proc/cpuinfo==
 <code>
-[root@centos8 ~]# cat /proc/cpuinfo
+[root@centos8 ~]# nmcli -p connection show ens18
-processor       : 0
+===============================================================================
-vendor_id       : GenuineIntel
+                      Connection profile details (ens18)
-cpu family      : 15
+===============================================================================
-model           : 6
+connection.id:                          ens18
-model name      : Common KVM processor
+connection.uuid:                        fc4a4d23-b15e-47a7-bcfa-b2e08f49553e
-stepping        : 1
+connection.stable-id:                   --
-microcode       : 0x1
+connection.type:                        802-3-ethernet
-cpu MHz         : 1999.987
+connection.interface-name:              ens18
-cache size      : 16384 KB
+connection.autoconnect:                 yes
-physical id     : 0
+connection.autoconnect-priority:        0
-siblings        : 4
+connection.autoconnect-retries:         -1 (default)
-core id         : 0
+connection.multi-connect:               0 (default)
-cpu cores       : 4
+connection.auth-retries:                -1
-apicid          : 0
+connection.timestamp:                   1630224060
-initial apicid  : 0
+connection.read-only:                   no
-fpu             : yes
+connection.permissions:                 --
-fpu_exception   : yes
+connection.zone:                        --
-cpuid level     : 13
+connection.master:                      --
-wp              : yes
+connection.slave-type:                  --
-flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx lm constant_tsc nopl xtopology cpuid tsc_known_freq pni cx16 x2apic hypervisor lahf_lm cpuid_fault pti
+connection.autoconnect-slaves:          -1 (default)
-bugs            : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf mds swapgs itlb_multihit
+connection.secondaries:                 --
-bogomips        : 3999.97
+connection.gateway-ping-timeout:        0
-clflush size    : 64
+connection.metered:                     unknown
-cache_alignment : 128
+connection.lldp:                        default
-address sizes   : 40 bits physical, 48 bits virtual
+connection.mdns:                        -1 (default)
-power management:
+connection.llmnr:                       -1 (default)
+connection.wait-device-timeout:         -1
-processor       : 1
+-------------------------------------------------------------------------------
-vendor_id       : GenuineIntel
+-3-ethernet.port:                    --
-cpu family      : 15
+-3-ethernet.speed:                   0
-model           : 6
+-3-ethernet.duplex:                  --
-model name      : Common KVM processor
+-3-ethernet.auto-negotiate:          no
-stepping        : 1
+-3-ethernet.mac-address:             --
-microcode       : 0x1
+-3-ethernet.cloned-mac-address:      --
-cpu MHz         : 1999.987
+-3-ethernet.generate-mac-address-mask:--
-cache size      : 16384 KB
+-3-ethernet.mac-address-blacklist:   --
-physical id     : 0
+-3-ethernet.mtu:                     auto
-siblings        : 4
+-3-ethernet.s390-subchannels:        --
-core id         : 1
+-3-ethernet.s390-nettype:            --
-cpu cores       : 4
+-3-ethernet.s390-options:            --
-apicid          : 1
+-3-ethernet.wake-on-lan:             default
-initial apicid  : 1
+-3-ethernet.wake-on-lan-password:    --
-fpu             : yes
+-------------------------------------------------------------------------------
-fpu_exception   : yes
+ipv4.method:                            manual
-cpuid level     : 13
+ipv4.dns:                               8.8.8.8
-wp              : yes
+ipv4.dns-search:                        ittraining.loc
-flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx lm constant_tsc nopl xtopology cpuid tsc_known_freq pni cx16 x2apic hypervisor lahf_lm cpuid_fault pti
+ipv4.dns-options:                       --
-bugs            : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf mds swapgs itlb_multihit
+ipv4.dns-priority:                      0
-bogomips        : 3999.97
+ipv4.addresses:                         10.0.2.45/24
-clflush size    : 64
+ipv4.gateway:                           10.0.2.1
-cache_alignment : 128
+ipv4.routes:                            --
-address sizes   : 40 bits physical, 48 bits virtual
+ipv4.route-metric:                      -1
-power management:
+ipv4.route-table:                       0 (unspec)
+ipv4.routing-rules:                     --
-processor       : 2
+ipv4.ignore-auto-routes:                no
-vendor_id       : GenuineIntel
+ipv4.ignore-auto-dns:                   no
-cpu family      : 15
+ipv4.dhcp-client-id:                    --
-model           : 6
+ipv4.dhcp-iaid:                         --
-model name      : Common KVM processor
+ipv4.dhcp-timeout:                      0 (default)
-stepping        : 1
+ipv4.dhcp-send-hostname:                yes
-microcode       : 0x1
+ipv4.dhcp-hostname:                     --
-cpu MHz         : 1999.987
+ipv4.dhcp-fqdn:                         --
-cache size      : 16384 KB
+ipv4.dhcp-hostname-flags:               0x0 (none)
-physical id     : 0
+ipv4.never-default:                     no
-siblings        : 4
+ipv4.may-fail:                          yes
-core id         : 2
+ipv4.dad-timeout:                       -1 (default)
-cpu cores       : 4
+ipv4.dhcp-vendor-class-identifier:      --
-apicid          : 2
+ipv4.dhcp-reject-servers:               --
-initial apicid  : 2
+-------------------------------------------------------------------------------
-fpu             : yes
+ipv6.method:                            auto
-fpu_exception   : yes
+ipv6.dns:                               --
-cpuid level     : 13
+ipv6.dns-search:                        --
-wp              : yes
+ipv6.dns-options:                       --
-flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx lm constant_tsc nopl xtopology cpuid tsc_known_freq pni cx16 x2apic hypervisor lahf_lm cpuid_fault pti
+ipv6.dns-priority:                      0
-bugs            : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf mds swapgs itlb_multihit
+ipv6.addresses:                         --
-bogomips        : 3999.97
+ipv6.gateway:                           --
-clflush size    : 64
+ipv6.routes:                            --
-cache_alignment : 128
+ipv6.route-metric:                      -1
-address sizes   : 40 bits physical, 48 bits virtual
+ipv6.route-table:                       0 (unspec)
-power management:
+ipv6.routing-rules:                     --
+ipv6.ignore-auto-routes:                no
-processor       : 3
+ipv6.ignore-auto-dns:                   no
-vendor_id       : GenuineIntel
+ipv6.never-default:                     no
-cpu family      : 15
+ipv6.may-fail:                          yes
-model           : 6
+ipv6.ip6-privacy:                       0 (disabled)
-model name      : Common KVM processor
+ipv6.addr-gen-mode:                     stable-privacy
-stepping        : 1
+ipv6.ra-timeout:                        0 (default)
-microcode       : 0x1
+ipv6.dhcp-duid:                         --
-cpu MHz         : 1999.987
+ipv6.dhcp-iaid:                         --
-cache size      : 16384 KB
+ipv6.dhcp-timeout:                      0 (default)
-physical id     : 0
+ipv6.dhcp-send-hostname:                yes
-siblings        : 4
+ipv6.dhcp-hostname:                     --
-core id         : 3
+ipv6.dhcp-hostname-flags:               0x0 (none)
-cpu cores       : 4
+ipv6.token:                             --
-apicid          : 3
+-------------------------------------------------------------------------------
-initial apicid  : 3
+proxy.method:                           none
-fpu             : yes
+proxy.browser-only:                     no
-fpu_exception   : yes
+proxy.pac-url:                          --
-cpuid level     : 13
+proxy.pac-script:                       --
-wp              : yes
+-------------------------------------------------------------------------------
-flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx lm constant_tsc nopl xtopology cpuid tsc_known_freq pni cx16 x2apic hypervisor lahf_lm cpuid_fault pti
+lines 56-100/100 (END)
-bugs            : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf mds swapgs itlb_multihit
+[q]
-bogomips        : 3999.97
-clflush size    : 64
-cache_alignment : 128
-address sizes   : 40 bits physical, 48 bits virtual
-power management:
-processor       : 4
-vendor_id       : GenuineIntel
-cpu family      : 15
-model           : 6
-model name      : Common KVM processor
-stepping        : 1
-microcode       : 0x1
-cpu MHz         : 1999.987
-cache size      : 16384 KB
-physical id     : 1
-siblings        : 4
-core id         : 0
-cpu cores       : 4
-apicid          : 4
-initial apicid  : 4
-fpu             : yes
-fpu_exception   : yes
-cpuid level     : 13
-wp              : yes
-flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx lm constant_tsc nopl xtopology cpuid tsc_known_freq pni cx16 x2apic hypervisor lahf_lm cpuid_fault pti
-bugs            : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf mds swapgs itlb_multihit
-bogomips        : 3999.97
-clflush size    : 64
-cache_alignment : 128
-address sizes   : 40 bits physical, 48 bits virtual
-power management:
-processor       : 5
-vendor_id       : GenuineIntel
-cpu family      : 15
-model           : 6
-model name      : Common KVM processor
-stepping        : 1
-microcode       : 0x1
-cpu MHz         : 1999.987
-cache size      : 16384 KB
-physical id     : 1
-siblings        : 4
-core id         : 1
-cpu cores       : 4
-apicid          : 5
-initial apicid  : 5
-fpu             : yes
-fpu_exception   : yes
-cpuid level     : 13
-wp              : yes
-flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx lm constant_tsc nopl xtopology cpuid tsc_known_freq pni cx16 x2apic hypervisor lahf_lm cpuid_fault pti
-bugs            : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf mds swapgs itlb_multihit
-bogomips        : 3999.97
-clflush size    : 64
-cache_alignment : 128
-address sizes   : 40 bits physical, 48 bits virtual
-power management:
-processor       : 6
-vendor_id       : GenuineIntel
-cpu family      : 15
-model           : 6
-model name      : Common KVM processor
-stepping        : 1
-microcode       : 0x1
-cpu MHz         : 1999.987
-cache size      : 16384 KB
-physical id     : 1
-siblings        : 4
-core id         : 2
-cpu cores       : 4
-apicid          : 6
-initial apicid  : 6
-fpu             : yes
-fpu_exception   : yes
-cpuid level     : 13
-wp              : yes
-flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx lm constant_tsc nopl xtopology cpuid tsc_known_freq pni cx16 x2apic hypervisor lahf_lm cpuid_fault pti
-bugs            : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf mds swapgs itlb_multihit
-bogomips        : 3999.97
-clflush size    : 64
-cache_alignment : 128
-address sizes   : 40 bits physical, 48 bits virtual
-power management:
-processor       : 7
-vendor_id       : GenuineIntel
-cpu family      : 15
-model           : 6
-model name      : Common KVM processor
-stepping        : 1
-microcode       : 0x1
-cpu MHz         : 1999.987
-cache size      : 16384 KB
-physical id     : 1
-siblings        : 4
-core id         : 3
-cpu cores       : 4
-apicid          : 7
-initial apicid  : 7
-fpu             : yes
-fpu_exception   : yes
-cpuid level     : 13
-wp              : yes
-flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx lm constant_tsc nopl xtopology cpuid tsc_known_freq pni cx16 x2apic hypervisor lahf_lm cpuid_fault pti
-bugs            : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf mds swapgs itlb_multihit
-bogomips        : 3999.97
-clflush size    : 64
-cache_alignment : 128
-address sizes   : 40 bits physical, 48 bits virtual
-power management:
 </code>
-==/proc/interrupts==
+To see the characteristics of the **ip_fixed** profile, use the following command:
 <code>
-[root@centos8 ~]# cat /proc/interrupts
+[root@centos8 ~]# nmcli -p connection show ip_fixed
-           CPU0       CPU1       CPU2       CPU3       CPU4       CPU5       CPU6       CPU7
+===============================================================================
-:        109          0          0          0          0          0          0          0   IO-APIC   2-edge      timer
+                     Connection profile details (ip_fixed)
-:          0          0          0          0          9          0          0          0   IO-APIC   1-edge      i8042
+===============================================================================
-:          0          0          0          0          0          1          0          0   IO-APIC   8-edge      rtc0
+connection.id:                          ip_fixed
-:          0          0          0          0          0          0          0          0   IO-APIC   9-fasteoi   acpi
+connection.uuid:                        0f48c74d-5d16-4c37-8220-24644507b589
-:          0          0          0          0      47098          0          0          0   IO-APIC  10-fasteoi   virtio0
+connection.stable-id:                   --
-:          0          0         31          0          0          0          0          0   IO-APIC  11-fasteoi   uhci_hcd:usb1
+connection.type:                        802-3-ethernet
-:          0          0          0         15          0          0          0          0   IO-APIC  12-edge      i8042
+connection.interface-name:              ens18
-:          0          0          0          0          0          0          0          0   IO-APIC  14-edge      ata_piix
+connection.autoconnect:                 yes
-:       7376          0        144          0          0          0          0      84588   IO-APIC  15-edge      ata_piix
+connection.autoconnect-priority:        0
-:          0          0          0          0          0          0          0          0   PCI-MSI 294912-edge      virtio1-config
+connection.autoconnect-retries:         -1 (default)
-:          0          0          0          0          0       5640          0         16   PCI-MSI 294913-edge      virtio1-input.0
+connection.multi-connect:               0 (default)
-:         36          0          0       5058          0          0          0          0   PCI-MSI 294914-edge      virtio1-output.0
+connection.auth-retries:                -1
-:          0      16008          0       9431          0          0          0          0   PCI-MSI 114688-edge      ahci[0000:00:07.0]
+connection.timestamp:                   1630224329
-NMI:          0          0          0          0          0          0          0          0   Non-maskable interrupts
+connection.read-only:                   no
-LOC:     870537     771900    1117711     288839     833717     502365     758229     405110   Local timer interrupts
+connection.permissions:                 --
-SPU:          0          0          0          0          0          0          0          0   Spurious interrupts
+connection.zone:                        --
-PMI:          0          0          0          0          0          0          0          0   Performance monitoring interrupts
+connection.master:                      --
-IWI:          0          0          0          0          2          0          0          0   IRQ work interrupts
+connection.slave-type:                  --
-RTR:          0          0          0          0          0          0          0          0   APIC ICR read retries
+connection.autoconnect-slaves:          -1 (default)
-RES:     178171      67749      43116      65994      71361     118585      54139      53452   Rescheduling interrupts
+connection.secondaries:                 --
-CAL:      11095      11007      10841      10343      14679       9998      12165      12443   Function call interrupts
+connection.gateway-ping-timeout:        0
-TLB:       2295       2297       2000       1728       2330       2338       1991       1861   TLB shootdowns
+connection.metered:                     unknown
-TRM:          0          0          0          0          0          0          0          0   Thermal event interrupts
+connection.lldp:                        default
-THR:          0          0          0          0          0          0          0          0   Threshold APIC interrupts
+connection.mdns:                        -1 (default)
-DFR:          0          0          0          0          0          0          0          0   Deferred Error APIC interrupts
+connection.llmnr:                       -1 (default)
-MCE:          0          0          0          0          0          0          0          0   Machine check exceptions
+connection.wait-device-timeout:         -1
-MCP:        288        288        288        288        288        288        288        288   Machine check polls
+-------------------------------------------------------------------------------
-HYP:          0          0          0          0          0          0          0          0   Hypervisor callback interrupts
+-3-ethernet.port:                    --
-HRE:          0          0          0          0          0          0          0          0   Hyper-V reenlightenment interrupts
+-3-ethernet.speed:                   0
-HVS:          0          0          0          0          0          0          0          0   Hyper-V stimer0 interrupts
+-3-ethernet.duplex:                  --
-ERR:          0
+-3-ethernet.auto-negotiate:          no
-MIS:          0
+-3-ethernet.mac-address:             --
-PIN:          0          0          0          0          0          0          0          0   Posted-interrupt notification event
+-3-ethernet.cloned-mac-address:      --
-NPI:          0          0          0          0          0          0          0          0   Nested posted-interrupt event
+-3-ethernet.generate-mac-address-mask:--
-PIW:          0          0          0          0          0          0          0          0   Posted-interrupt wakeup event
+-3-ethernet.mac-address-blacklist:   --
+-3-ethernet.mtu:                     auto
+-3-ethernet.s390-subchannels:        --
+-3-ethernet.s390-nettype:            --
+-3-ethernet.s390-options:            --
+-3-ethernet.wake-on-lan:             default
+-3-ethernet.wake-on-lan-password:    --
+-------------------------------------------------------------------------------
+ipv4.method:                            manual
+ipv4.dns:                               --
+ipv4.dns-search:                        --
+ipv4.dns-options:                       --
+ipv4.dns-priority:                      0
+ipv4.addresses:                         10.0.2.46/24
+ipv4.gateway:                           10.0.2.1
+ipv4.routes:                            --
+ipv4.route-metric:                      -1
+ipv4.route-table:                       0 (unspec)
+ipv4.routing-rules:                     --
+ipv4.ignore-auto-routes:                no
+ipv4.ignore-auto-dns:                   no
+ipv4.dhcp-client-id:                    --
+ipv4.dhcp-iaid:                         --
+ipv4.dhcp-timeout:                      0 (default)
+ipv4.dhcp-send-hostname:                yes
+ipv4.dhcp-hostname:                     --
+ipv4.dhcp-fqdn:                         --
+ipv4.dhcp-hostname-flags:               0x0 (none)
+ipv4.never-default:                     no
+ipv4.may-fail:                          yes
+ipv4.dad-timeout:                       -1 (default)
+ipv4.dhcp-vendor-class-identifier:      --
+ipv4.dhcp-reject-servers:               --
+-------------------------------------------------------------------------------
+ipv6.method:                            auto
+ipv6.dns:                               --
+ipv6.dns-search:                        --
+ipv6.dns-options:                       --
+ipv6.dns-priority:                      0
+ipv6.addresses:                         --
+ipv6.gateway:                           --
+ipv6.routes:                            --
+ipv6.route-metric:                      -1
+ipv6.route-table:                       0 (unspec)
+ipv6.routing-rules:                     --
+ipv6.ignore-auto-routes:                no
+ipv6.ignore-auto-dns:                   no
+ipv6.never-default:                     no
+ipv6.may-fail:                          yes
+ipv6.ip6-privacy:                       -1 (unknown)
+ipv6.addr-gen-mode:                     stable-privacy
+ipv6.ra-timeout:                        0 (default)
+ipv6.dhcp-duid:                         --
+ipv6.dhcp-iaid:                         --
+ipv6.dhcp-timeout:                      0 (default)
+ipv6.dhcp-send-hostname:                yes
+ipv6.dhcp-hostname:                     --
+ipv6.dhcp-hostname-flags:               0x0 (none)
+ipv6.token:                             --
+-------------------------------------------------------------------------------
+proxy.method:                           none
+proxy.browser-only:                     no
+proxy.pac-url:                          --
+proxy.pac-script:                       --
+-------------------------------------------------------------------------------
+===============================================================================
+      Activate connection details (0f48c74d-5d16-4c37-8220-24644507b589)
+===============================================================================
+GENERAL.NAME:                           ip_fixed
+GENERAL.UUID:                           0f48c74d-5d16-4c37-8220-24644507b589
+GENERAL.DEVICES:                        ens18
+GENERAL.IP-IFACE:                       ens18
+GENERAL.STATE:                          activated
+GENERAL.DEFAULT:                        yes
+GENERAL.DEFAULT6:                       no
+GENERAL.SPEC-OBJECT:                    --
+GENERAL.VPN:                            no
+GENERAL.DBUS-PATH:                      /org/freedesktop/NetworkManager/ActiveConnection/4
+GENERAL.CON-PATH:                       /org/freedesktop/NetworkManager/Settings/4
+GENERAL.ZONE:                           --
+GENERAL.MASTER-PATH:                    --
+-------------------------------------------------------------------------------
+IP4.ADDRESS[1]:                         10.0.2.46/24
+IP4.GATEWAY:                            10.0.2.1
+IP4.ROUTE[1]:                           dst = 10.0.2.0/24, nh = 0.0.0.0, mt = 100
+IP4.ROUTE[2]:                           dst = 0.0.0.0/0, nh = 10.0.2.1, mt = 100
+-------------------------------------------------------------------------------
+IP6.ADDRESS[1]:                         fe80::5223:aee1:998e:9f27/64
+IP6.GATEWAY:                            --
+IP6.ROUTE[1]:                           dst = fe80::/64, nh = ::, mt = 100
+IP6.ROUTE[2]:                           dst = ff00::/8, nh = ::, mt = 256, table=255
+-------------------------------------------------------------------------------
+lines 83-127/127 (END)
+[q]
 </code>
-<WRAP center round important 60%>
+To see a list of the profiles associated with a device, use the following command:
-**Important** : The use of an IRQ by a peripheral is exclusive.
-</WRAP>
-==/proc/dma==
 <code>
-[root@centos8 ~]# cat /proc/dma
+[root@centos8 ~]# nmcli -f CONNECTIONS device show ens18
-: cascade
+CONNECTIONS.AVAILABLE-CONNECTION-PATHS: /org/freedesktop/NetworkManager/Settings/1,/org/freedesktop/NetworkManager/Settings/4
+CONNECTIONS.AVAILABLE-CONNECTIONS[1]:   fc4a4d23-b15e-47a7-bcfa-b2e08f49553e | ens18
+CONNECTIONS.AVAILABLE-CONNECTIONS[2]:   0f48c74d-5d16-4c37-8220-24644507b589 | ip_fixed
 </code>
-==/proc/ioports==
+The configuration files for the **ens18** device can be found in the **/etc/sysconfig/network-scripts/** directory:
 <code>
-root@centos8 ~]# cat /proc/ioports | more
+[root@centos8 ~]# ls -l /etc/sysconfig/network-scripts/ | grep ifcfg
--0cf7 : PCI Bus 0000:00
+-rw-r--r--. 1 root root 417 Jun 16 06:39 ifcfg-ens18
--001f : dma1
+-rw-r--r--. 1 root root 326 Aug 29 03:58 ifcfg-ip_fixed
--0021 : pic1
--0043 : timer0
--0053 : timer1
--0060 : keyboard
--0064 : keyboard
--0077 : rtc0
--008f : dma page reg
-a0-00a1 : pic2
-c0-00df : dma2
-f0-00ff : fpu
--0177 : 0000:00:01.1
--0177 : ata_piix
-f0-01f7 : 0000:00:01.1
-f0-01f7 : ata_piix
--0376 : 0000:00:01.1
--0376 : ata_piix
-c0-03df : vga+
-f6-03f6 : 0000:00:01.1
-f6-03f6 : ata_piix
---More--
 </code>
-<WRAP center round alert 60%>
+====1.2 - Name Resolution====
-**Important** - If two peripherals use the same IO Port, both become unusable.
-</WRAP>
-==/proc/devices==
+Looking at the **/etc/sysconfig/network-scripts/ifcfg-ip_fixed** file reveals that their is currently no DNS entry:
 <code>
-[root@centos8 ~]# cat /proc/devices
+[root@centos8 ~]# cat /etc/sysconfig/network-scripts/ifcfg-ip_fixed
-Character devices:
+TYPE=Ethernet
-mem
+PROXY_METHOD=none
- /dev/vc/0
+BROWSER_ONLY=no
-tty
+BOOTPROTO=none
-ttyS
+IPADDR=10.0.2.46
-/dev/tty
+PREFIX=24
-/dev/console
+GATEWAY=10.0.2.1
-/dev/ptmx
+DEFROUTE=yes
-vcs
+IPV4_FAILURE_FATAL=no
- misc
+IPV6INIT=yes
-input
+IPV6_AUTOCONF=yes
-sg
+IPV6_DEFROUTE=yes
-fb
+IPV6_FAILURE_FATAL=no
-ptm
+IPV6_ADDR_GEN_MODE=stable-privacy
-pts
+NAME=ip_fixed
-raw
+UUID=0f48c74d-5d16-4c37-8220-24644507b589
-usb
+DEVICE=ens18
-ttyUSB
+ONBOOT=yes
-usb_device
-cpu/msr
-cpu/cpuid
-drm
-aux
-hidraw
-usbmon
-bsg
-watchdog
-ptp
-pps
-rtc
-dax
-tpm
-gpiochip
-Block devices:
-sd
-md
-sr
-sd
-sd
-sd
-sd
-sd
-sd
-sd
-sd
-sd
-sd
-sd
-sd
-sd
-sd
-sd
-device-mapper
-mdp
-blkext
 </code>
-==/proc/modules==
+As a result there is currently no name resolution :
 <code>
-[root@centos8 ~]# cat /proc/modules | more
+[root@centos8 ~]# ping www.free.fr
-xt_CHECKSUM 16384 1 - Live 0xffffffffc09a8000
+ping: www.free.fr: Name or service not known
-ipt_MASQUERADE 16384 3 - Live 0xffffffffc09a3000
-xt_conntrack 16384 1 - Live 0xffffffffc099e000
-ipt_REJECT 16384 2 - Live 0xffffffffc0999000
-nft_compat 20480 16 - Live 0xffffffffc0993000
-nf_nat_tftp 16384 0 - Live 0xffffffffc098b000
-nft_objref 16384 1 - Live 0xffffffffc0986000
-nf_conntrack_tftp 16384 3 nf_nat_tftp, Live 0xffffffffc0981000
-nft_counter 16384 33 - Live 0xffffffffc097c000
-tun 53248 1 - Live 0xffffffffc096e000
-bridge 192512 0 - Live 0xffffffffc093e000
-stp 16384 1 bridge, Live 0xffffffffc0939000
-llc 16384 2 bridge,stp, Live 0xffffffffc0930000
-nft_fib_inet 16384 1 - Live 0xffffffffc08f5000
-nft_fib_ipv4 16384 1 nft_fib_inet, Live 0xffffffffc08ed000
-nft_fib_ipv6 16384 1 nft_fib_inet, Live 0xffffffffc08e8000
-nft_fib 16384 3 nft_fib_inet,nft_fib_ipv4,nft_fib_ipv6, Live 0xffffffffc08e3000
-nft_reject_inet 16384 5 - Live 0xffffffffc08de000
-nf_reject_ipv4 16384 2 ipt_REJECT,nft_reject_inet, Live 0xffffffffc08d9000
-nf_reject_ipv6 16384 1 nft_reject_inet, Live 0xffffffffc08d4000
-nft_reject 16384 1 nft_reject_inet, Live 0xffffffffc08cf000
---More--
 </code>
-==/proc/diskstats==
+Modify the **ip_fixed** profile to rectify this:
 <code>
-[root@centos8 ~]# cat /proc/diskstats
+[root@centos8 ~]# nmcli connection mod ip_fixed ipv4.dns 8.8.8.8
-       0 sda 15481 112 1445637 154103 10272 2377 277530 890611 0 237219 1044714 0 0 0 0
-       1 sda1 402 3 66754 13349 31 18 392 4632 0 2824 17981 0 0 0 0
-       2 sda2 14915 109 1375516 140528 8450 2359 277138 869788 0 225416 1010316 0 0 0 0
-      16 sdb 230 0 5991 36 0 0 0 0 0 110 36 0 0 0 0
-       0 sr0 10 0 4 2 0 0 0 0 0 9 2 0 0 0 0
-       0 dm-0 11651 0 1364532 72138 12121 0 288727 1208138 0 227630 1280276 0 0 0 0
-       1 dm-1 104 0 4440 79 0 0 0 0 0 71 79 0 0 0 0
 </code>
-==/proc/partitions==
+Consulting the **/etc/sysconfig/network-scripts/ifcfg-ip_fixed** file shows that a DNS server has been added:
 <code>
-[root@centos8 ~]# cat /proc/partitions
+[root@centos8 ~]# cat /etc/sysconfig/network-scripts/ifcfg-ip_fixed
-major minor  #blocks  name
+TYPE=Ethernet
+PROXY_METHOD=none
-        0   33554432 sda
+BROWSER_ONLY=no
-        1    1048576 sda1
+BOOTPROTO=none
-        2   32504832 sda2
+IPADDR=10.0.2.46
-       16    4194304 sdb
+PREFIX=24
-        0    1048575 sr0
+GATEWAY=10.0.2.1
-        0   29143040 dm-0
+DEFROUTE=yes
-        1    3358720 dm-1
+IPV4_FAILURE_FATAL=no
+IPV6INIT=yes
+IPV6_AUTOCONF=yes
+IPV6_DEFROUTE=yes
+IPV6_FAILURE_FATAL=no
+IPV6_ADDR_GEN_MODE=stable-privacy
+NAME=ip_fixed
+UUID=0f48c74d-5d16-4c37-8220-24644507b589
+DEVICE=ens18
+ONBOOT=yes
+DNS1=8.8.8.8
 </code>
-==/proc/swaps==
+Restart the NetworkManager service to apply this change:
 <code>
-[root@centos8 ~]# cat /proc/swaps
+root@centos8 ~]# systemctl restart NetworkManager.service
-Filename                                Type            Size    Used    Priority
+[root@centos8 ~]# systemctl status NetworkManager.service
-/dev/dm-1                               partition       3358716 0       -2
+● NetworkManager.service - Network Manager
-</code>
+   Loaded: loaded (/usr/lib/systemd/system/NetworkManager.service; enabled; vendor preset: enabled)
+   Active: active (running) since Sun 2021-08-29 04:15:11 EDT; 8s ago
+     Docs: man:NetworkManager(8)
+ Main PID: 973390 (NetworkManager)
+    Tasks: 4 (limit: 23535)
+   Memory: 4.6M
+   CGroup: /system.slice/NetworkManager.service
+           └─973390 /usr/sbin/NetworkManager --no-daemon
-==/proc/loadavg==
+Aug 29 04:15:12 centos8.ittraining.loc NetworkManager[973390]: <info>  [1630224912.2235] device (ens18): state change: ip-check -> secondaries (reas>
+Aug 29 04:15:12 centos8.ittraining.loc NetworkManager[973390]: <info>  [1630224912.2237] device (virbr0): state change: secondaries -> activated (re>
-<code>
+Aug 29 04:15:12 centos8.ittraining.loc NetworkManager[973390]: <info>  [1630224912.2241] manager: NetworkManager state is now CONNECTED_LOCAL
-[root@centos8 ~]# cat /proc/loadavg
+Aug 29 04:15:12 centos8.ittraining.loc NetworkManager[973390]: <info>  [1630224912.2251] policy: set 'ip_fixed' (ens18) as default for IPv4 routing a>
-.00 0.00 0.00 1/697 16936
+Aug 29 04:15:12 centos8.ittraining.loc NetworkManager[973390]: <info>  [1630224912.3090] device (virbr0): Activation: successful, device activated.
+Aug 29 04:15:12 centos8.ittraining.loc NetworkManager[973390]: <info>  [1630224912.3098] device (ens18): state change: secondaries -> activated (rea>
+Aug 29 04:15:12 centos8.ittraining.loc NetworkManager[973390]: <info>  [1630224912.3102] manager: NetworkManager state is now CONNECTED_SITE
+Aug 29 04:15:12 centos8.ittraining.loc NetworkManager[973390]: <info>  [1630224912.3111] device (ens18): Activation: successful, device activated.
+Aug 29 04:15:12 centos8.ittraining.loc NetworkManager[973390]: <info>  [1630224912.3116] manager: NetworkManager state is now CONNECTED_GLOBAL
+Aug 29 04:15:12 centos8.ittraining.loc NetworkManager[973390]: <info>  [1630224912.3121] manager: startup complete
+lines 1-20/20 (END)
+[q]
 </code>
-==/proc/meminfo==
+Now check that the **/etc/resolv.conf** file has been modified to check the change made:
 <code>
-[root@centos8 ~]# cat /proc/meminfo
+[root@centos8 ~]# cat /etc/resolv.conf
-MemTotal:        3825032 kB
+# Generated by NetworkManager
-MemFree:         1862116 kB
+search ittraining.loc
-MemAvailable:    2420560 kB
+nameserver 8.8.8.8
-Buffers:            3300 kB
-Cached:           750496 kB
-SwapCached:            0 kB
-Active:           315572 kB
-Inactive:        1400260 kB
-Active(anon):       1856 kB
-Inactive(anon):   974728 kB
-Active(file):     313716 kB
-Inactive(file):   425532 kB
-Unevictable:           0 kB
-Mlocked:               0 kB
-SwapTotal:       3358716 kB
-SwapFree:        3358716 kB
-Dirty:                 0 kB
-Writeback:             0 kB
-AnonPages:        962004 kB
-Mapped:           261084 kB
-Shmem:             14552 kB
-KReclaimable:      46980 kB
-Slab:             118396 kB
-SReclaimable:      46980 kB
-SUnreclaim:        71416 kB
-KernelStack:       11280 kB
-PageTables:        46532 kB
-NFS_Unstable:          0 kB
-Bounce:                0 kB
-WritebackTmp:          0 kB
-CommitLimit:     5271232 kB
-Committed_AS:    5072744 kB
-VmallocTotal:   34359738367 kB
-VmallocUsed:           0 kB
-VmallocChunk:          0 kB
-Percpu:             5920 kB
-HardwareCorrupted:     0 kB
-AnonHugePages:    546816 kB
-ShmemHugePages:        0 kB
-ShmemPmdMapped:        0 kB
-FileHugePages:         0 kB
-FilePmdMapped:         0 kB
-HugePages_Total:       0
-HugePages_Free:        0
-HugePages_Rsvd:        0
-HugePages_Surp:        0
-Hugepagesize:       2048 kB
-Hugetlb:               0 kB
-DirectMap4k:      173944 kB
-DirectMap2M:     4020224 kB
 </code>
-==/proc/version==
+Lastly, check the name resolution:
 <code>
-[root@centos8 ~]# cat /proc/version
+[root@centos8 ~]# ping www.free.fr
-Linux version 4.18.0-305.3.1.el8.x86_64 (mockbuild@kbuilder.bsys.centos.org) (gcc version 8.4.1 20200928 (Red Hat 8.4.1-1) (GCC)) #1 SMP Tue Jun 1 16:14:33 UTC 2021
+PING www.free.fr (212.27.48.10) 56(84) bytes of data.
+bytes from www.free.fr (212.27.48.10): icmp_seq=1 ttl=47 time=29.3 ms
+bytes from www.free.fr (212.27.48.10): icmp_seq=2 ttl=47 time=29.4 ms
+bytes from www.free.fr (212.27.48.10): icmp_seq=3 ttl=47 time=29.4 ms
+bytes from www.free.fr (212.27.48.10): icmp_seq=4 ttl=47 time=29.4 ms
+^C
+--- www.free.fr ping statistics ---
+packets transmitted, 4 received, 0% packet loss, time 3005ms
+rtt min/avg/max/mdev = 29.266/29.377/29.428/0.183 ms
 </code>
-===Répertoires===
+<WRAP center round important 60%>
+**Important** : Notez qu'il existe un front-end graphique en mode texte, **nmtui**, pour configurer NetworkManager.
+</WRAP>
-==ide/scsi==
+====1.3 - Adding a Second IP Addresse to a Profile====
-This sub-directory contains disk capacity, disk type and disk geometry information.
+To add a second IP address, use the following command:
-==acpi==
-This sub-directory contains information on energy management, temperatures, fan speeds and battery levels.
-==bus==
-This sub-directory contains a sub-directory for each bus.
-==net==
-This sub-directory contains information concerning the network.
-==sys==
-This sub-directory contains files used by root to configure the kernel. For instance, the following command configiresthe kernel to ignore incoming pings:
-  # echo 1 > /proc/sys/net/ipv4/icmp_echo_ignore_all [Enter]
-====2.2 - Using the sysctl Command====
-Files in the **/proc/sys** can be administered by using the **sysctl** command.
-The **sysctl** command applies rules at system boot that are defined in the **/etc/sysctl.conf** file:
 <code>
-[root@centos8 ~]# cat /etc/sysctl.conf
+[root@centos8 ~]# nmcli connection mod ip_fixed +ipv4.addresses 192.168.1.2/24
-# sysctl settings are defined through files in
-# /usr/lib/sysctl.d/, /run/sysctl.d/, and /etc/sysctl.d/.
-#
-# Vendors settings live in /usr/lib/sysctl.d/.
-# To override a whole file, create a new file with the same in
-# /etc/sysctl.d/ and put new settings there. To override
-# only specific settings, add a file with a lexically later
-# name in /etc/sysctl.d/ and put new settings there.
-#
-# For more information, see sysctl.conf(5) and sysctl.d(5).
-[root@centos8 ~]# ls -l /etc/sysctl.d/
-total 0
-lrwxrwxrwx. 1 root root 14 Mar 16 15:42 99-sysctl.conf -> ../sysctl.conf
-[root@centos8 ~]# ls -l /usr/lib/sysctl.d/
-total 24
--rw-r--r--. 1 root root 1810 Dec 22  2020 10-default-yama-scope.conf
--rw-r--r--. 1 root root  524 Mar 16 15:42 50-coredump.conf
--rw-r--r--. 1 root root 1270 Mar 16 15:42 50-default.conf
--rw-r--r--. 1 root root  246 Jun 15  2020 50-libkcapi-optmem_max.conf
--rw-r--r--. 1 root root  636 Mar 16 15:42 50-pid-max.conf
--rw-r--r--. 1 root root  499 Nov 26  2019 60-libvirtd.conf
-[root@centos8 ~]# cat /usr/lib/sysctl.d/50-default.conf
-#  This file is part of systemd.
-#
-#  systemd is free software; you can redistribute it and/or modify it
-#  under the terms of the GNU Lesser General Public License as published by
-#  the Free Software Foundation; either version 2.1 of the License, or
-#  (at your option) any later version.
-# See sysctl.d(5) and core(5) for documentation.
-# To override settings in this file, create a local file in /etc
-# (e.g. /etc/sysctl.d/90-override.conf), and put any assignments
-# there.
-# System Request functionality of the kernel (SYNC)
-#
-# Use kernel.sysrq = 1 to allow all keys.
-# See https://www.kernel.org/doc/html/latest/admin-guide/sysrq.html for a list
-# of values and keys.
-kernel.sysrq = 16
-# Append the PID to the core filename
-kernel.core_uses_pid = 1
-# https://bugzilla.redhat.com/show_bug.cgi?id=1689346
-kernel.kptr_restrict = 1
-# Source route verification
-net.ipv4.conf.all.rp_filter = 1
-# Do not accept source routing
-net.ipv4.conf.all.accept_source_route = 0
-# Promote secondary addresses when the primary address is removed
-net.ipv4.conf.all.promote_secondaries = 1
-# Fair Queue CoDel packet scheduler to fight bufferbloat
-net.core.default_qdisc = fq_codel
-# Enable hard and soft link protection
-fs.protected_hardlinks = 1
-fs.protected_symlinks = 1
 </code>
-The command line switches of this command are:
+Reload the profile:
 <code>
-Usage:
+[root@centos8 ~]# nmcli con up ip_fixed
- sysctl [options] [variable[=value] ...]
-Options:
-  -a, --all            display all variables
-  -A                   alias of -a
-  -X                   alias of -a
-      --deprecated     include deprecated parameters to listing
-  -b, --binary         print value without new line
-  -e, --ignore         ignore unknown variables errors
-  -N, --names          print variable names without values
-  -n, --values         print only values of the given variable(s)
-  -p, --load[=<file>]  read values from file
-  -f                   alias of -p
-      --system         read values from all system directories
-  -r, --pattern <expression>
-                       select setting that match expression
-  -q, --quiet          do not echo variable set
-  -w, --write          enable writing a value to variable
-  -o                   does nothing
-  -x                   does nothing
-  -d                   alias of -h
- -h, --help     display this help and exit
- -V, --version  output version information and exit
-For more details see sysctl(8).
 </code>
-=====LAB#3 - Interpreting Information in /proc=====
+Check that the new IP address is visible:
-The information found in files in the /proc filesystem can be interpreted using the following commands:
-  * free,
-  * uptime et w,
-  * iostat,
-  * hdparm
-  * vmstat,
-  * mpstat,
-  * sar.
-====3.1 - The free Command====
-The **free** command shows total, used, free, shared, buffered, cached and swapped memory:
 <code>
-[root@centos8 ~]# free -m
+[root@centos8 ~]# nmcli connection show ip_fixed
-              total        used        free      shared  buff/cache   available
+connection.id:                          ip_fixed
-Mem:           3735        1135        1818          14         782        2363
+connection.uuid:                        0f48c74d-5d16-4c37-8220-24644507b589
-Swap:          3279           0        3279
+connection.stable-id:                   --
+connection.type:                        802-3-ethernet
+connection.interface-name:              ens18
+connection.autoconnect:                 yes
+connection.autoconnect-priority:        0
+connection.autoconnect-retries:         -1 (default)
+connection.multi-connect:               0 (default)
+connection.auth-retries:                -1
+connection.timestamp:                   1630225792
+connection.read-only:                   no
+connection.permissions:                 --
+connection.zone:                        --
+connection.master:                      --
+connection.slave-type:                  --
+connection.autoconnect-slaves:          -1 (default)
+connection.secondaries:                 --
+connection.gateway-ping-timeout:        0
+connection.metered:                     unknown
+connection.lldp:                        default
+connection.mdns:                        -1 (default)
+connection.llmnr:                       -1 (default)
+connection.wait-device-timeout:         -1
+-3-ethernet.port:                    --
+-3-ethernet.speed:                   0
+-3-ethernet.duplex:                  --
+-3-ethernet.auto-negotiate:          no
+-3-ethernet.mac-address:             --
+-3-ethernet.cloned-mac-address:      --
+-3-ethernet.generate-mac-address-mask:--
+-3-ethernet.mac-address-blacklist:   --
+-3-ethernet.mtu:                     auto
+-3-ethernet.s390-subchannels:        --
+-3-ethernet.s390-nettype:            --
+-3-ethernet.s390-options:            --
+-3-ethernet.wake-on-lan:             default
+-3-ethernet.wake-on-lan-password:    --
+ipv4.method:                            manual
+ipv4.dns:                               8.8.8.8
+ipv4.dns-search:                        --
+ipv4.dns-options:                       --
+ipv4.dns-priority:                      0
+ipv4.addresses:                         10.0.2.46/24, 192.168.1.2/24
+ipv4.gateway:                           10.0.2.1
+ipv4.routes:                            --
+ipv4.route-metric:                      -1
+ipv4.route-table:                       0 (unspec)
+ipv4.routing-rules:                     --
+ipv4.ignore-auto-routes:                no
+ipv4.ignore-auto-dns:                   no
+ipv4.dhcp-client-id:                    --
+ipv4.dhcp-iaid:                         --
+ipv4.dhcp-timeout:                      0 (default)
+ipv4.dhcp-send-hostname:                yes
+ipv4.dhcp-hostname:                     --
+ipv4.dhcp-fqdn:                         --
+ipv4.dhcp-hostname-flags:               0x0 (none)
+ipv4.never-default:                     no
+ipv4.may-fail:                          yes
+ipv4.dad-timeout:                       -1 (default)
+ipv4.dhcp-vendor-class-identifier:      --
+ipv4.dhcp-reject-servers:               --
+ipv6.method:                            auto
+ipv6.dns:                               --
+ipv6.dns-search:                        --
+ipv6.dns-options:                       --
+ipv6.dns-priority:                      0
+ipv6.addresses:                         --
+ipv6.gateway:                           --
+ipv6.routes:                            --
+ipv6.route-metric:                      -1
+ipv6.route-table:                       0 (unspec)
+ipv6.routing-rules:                     --
+ipv6.ignore-auto-routes:                no
+ipv6.ignore-auto-dns:                   no
+ipv6.never-default:                     no
+ipv6.may-fail:                          yes
+ipv6.ip6-privacy:                       -1 (unknown)
+ipv6.addr-gen-mode:                     stable-privacy
+ipv6.ra-timeout:                        0 (default)
+ipv6.dhcp-duid:                         --
+ipv6.dhcp-iaid:                         --
+ipv6.dhcp-timeout:                      0 (default)
+ipv6.dhcp-send-hostname:                yes
+ipv6.dhcp-hostname:                     --
+ipv6.dhcp-hostname-flags:               0x0 (none)
+ipv6.token:                             --
+proxy.method:                           none
+proxy.browser-only:                     no
+proxy.pac-url:                          --
+proxy.pac-script:                       --
+GENERAL.NAME:                           ip_fixed
+GENERAL.UUID:                           0f48c74d-5d16-4c37-8220-24644507b589
+GENERAL.DEVICES:                        ens18
+GENERAL.IP-IFACE:                       ens18
+GENERAL.STATE:                          activated
+GENERAL.DEFAULT:                        yes
+GENERAL.DEFAULT6:                       no
+GENERAL.SPEC-OBJECT:                    --
+GENERAL.VPN:                            no
+GENERAL.DBUS-PATH:                      /org/freedesktop/NetworkManager/ActiveConnection/3
+GENERAL.CON-PATH:                       /org/freedesktop/NetworkManager/Settings/2
+GENERAL.ZONE:                           --
+GENERAL.MASTER-PATH:                    --
+IP4.ADDRESS[1]:                         10.0.2.46/24
+IP4.ADDRESS[2]:                         192.168.1.2/24
+IP4.GATEWAY:                            10.0.2.1
+IP4.ROUTE[1]:                           dst = 10.0.2.0/24, nh = 0.0.0.0, mt = 100
+IP4.ROUTE[2]:                           dst = 192.168.1.0/24, nh = 0.0.0.0, mt = 100
+IP4.ROUTE[3]:                           dst = 0.0.0.0/0, nh = 10.0.2.1, mt = 100
+IP4.DNS[1]:                             8.8.8.8
+IP6.ADDRESS[1]:                         fe80::5223:aee1:998e:9f27/64
+IP6.GATEWAY:                            --
+IP6.ROUTE[1]:                           dst = fe80::/64, nh = ::, mt = 100
+IP6.ROUTE[2]:                           dst = ff00::/8, nh = ::, mt = 256, table=255
+lines 72-116/116 (END)
+[q]
 </code>
-In the above example, you can see:
+<WRAP center round important 60%>
+**Important** : Note the second address on the **ipv4.addresses: ** line and the addition of the **IP4.ADDRESS[2]:** line.
+</WRAP>
-  * 3735 MB of total physical memory,
+Now check the **/etc/sysconfig/network-scripts/ifcfg-ip_fixed** file:
-  * 1135 MB of used physical memory and 1818 MB of free physical memory,
-  * 3279 MB of swap space with 0MB being used.
-The command line switches of this command are:
 <code>
-[root@centos8 ~]# free --help
+[root@centos8 ~]# cat /etc/sysconfig/network-scripts/ifcfg-ip_fixed
+TYPE=Ethernet
-Usage:
+PROXY_METHOD=none
- free [options]
+BROWSER_ONLY=no
+BOOTPROTO=none
-Options:
+IPADDR=10.0.2.46
- -b, --bytes         show output in bytes
+PREFIX=24
-     --kilo          show output in kilobytes
+GATEWAY=10.0.2.1
-     --mega          show output in megabytes
+DEFROUTE=yes
-     --giga          show output in gigabytes
+IPV4_FAILURE_FATAL=no
-     --tera          show output in terabytes
+IPV6INIT=yes
-     --peta          show output in petabytes
+IPV6_AUTOCONF=yes
- -k, --kibi          show output in kibibytes
+IPV6_DEFROUTE=yes
- -m, --mebi          show output in mebibytes
+IPV6_FAILURE_FATAL=no
- -g, --gibi          show output in gibibytes
+IPV6_ADDR_GEN_MODE=stable-privacy
-     --tebi          show output in tebibytes
+NAME=ip_fixed
-     --pebi          show output in pebibytes
+UUID=0f48c74d-5d16-4c37-8220-24644507b589
- -h, --human         show human-readable output
+DEVICE=ens18
-     --si            use powers of 1000 not 1024
+ONBOOT=yes
- -l, --lohi          show detailed low and high memory statistics
+DNS1=8.8.8.8
- -t, --total         show total for RAM + swap
+IPADDR1=192.168.1.2
- -s N, --seconds N   repeat printing every N seconds
+PREFIX1=24
- -c N, --count N     repeat printing N times, then exit
- -w, --wide          wide output
-     --help     display this help and exit
- -V, --version  output version information and exit
-For more details see free(1).
 </code>
-====3.2 - The uptime and w Commands====
+<WRAP center round important 60%>
+**Important** : Note the addition of the **IPADDR1=192.168.1.2** line.
-Each of these commands show the load average over the past 1, 5 and 15 minutes:
+</WRAP>
-<code>
-[root@centos8 ~]# uptime
-:39:03 up 1 day,  2:34,  1 user,  load average: 0.00, 0.00, 0.00
-[root@centos8 ~]# w
-:39:04 up 1 day,  2:34,  1 user,  load average: 0.00, 0.00, 0.00
-USER     TTY      FROM             LOGIN@   IDLE   JCPU   PCPU WHAT
-trainee  pts/0    10.0.2.1         03:58    0.00s  0.11s  0.02s sshd: trainee [priv]
-</code>
-The **load average** indicates the number of processes being executed and waiting to be executed for the period concerned.
-If the load average of a single-core system was **3.48  4.00  3.85** this would indicate a bottleneck since, on average:
-  * 2.48 processes would have been waiting to be executed over the last minute,
+====1.4 - The hostname Command====
-  * 3.00 processes would have been waiting to be executed over the last 5 minutes,
-  * 2.85 processes would have been waiting to be executed over the last 15 minutes,
-The command line switches of these commands are:
+Any change to the hostname is immediate and permanent:
 <code>
-[root@centos8 ~]# uptime --help
+[root@centos8 ~]# hostname
+centos8.ittraining.loc
-Usage:
+[root@centos8 ~]# nmcli general hostname centos.ittraining.loc
- uptime [options]
-Options:
+[root@centos8 ~]# cat /etc/hostname
- -p, --pretty   show uptime in pretty format
+centos.ittraining.loc
- -h, --help     display this help and exit
- -s, --since    system up since
- -V, --version  output version information and exit
-For more details see uptime(1).
+[root@centos8 ~]# hostname
+centos.ittraining.loc
-[root@centos8 ~]# w --help
+[root@centos8 ~]# nmcli general hostname centos8.ittraining.loc
-Usage:
- w [options]
-Options:
- -h, --no-header     do not print header
- -u, --no-current    ignore current process username
- -s, --short         short format
- -f, --from          show remote hostname field
- -o, --old-style     old style output
- -i, --ip-addr       display IP address instead of hostname (if possible)
-     --help     display this help and exit
+[root@centos8 ~]# cat /etc/hostname
- -V, --version  output version information and exit
+centos8.ittraining.loc
-For more details see w(1).
+[root@centos8 ~]# hostname
+centos8.ittraining.loc
 </code>
-====3.3 - The iostat Command====
+====1.5 - The ip Command====
-The **iostat** command show disk, terminal and streamer statistics:
+Use of the **ip** command is now preferred over the use of the ifconfig command:
 <code>
-[root@centos8 ~]# iostat
+[root@centos8 ~]# ip address
-bash: iostat: command not found...
+: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
-Install package 'sysstat' to provide command 'iostat'? [N/y] y
+    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
+    inet 127.0.0.1/8 scope host lo
+       valid_lft forever preferred_lft forever
- * Waiting in queue...
+    inet6 ::1/128 scope host
-The following packages have to be installed:
+       valid_lft forever preferred_lft forever
- lm_sensors-libs-3.4.0-22.20180522git70f7e08.el8.x86_64 Lm_sensors core libraries
+: ens18: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
- sysstat-11.7.3-5.el8.x86_64    Collection of performance monitoring tools for Linux
+    link/ether 4e:b1:31:bd:5d:b2 brd ff:ff:ff:ff:ff:ff
-Proceed with changes? [N/y] y
+    inet 10.0.2.46/24 brd 10.0.2.255 scope global noprefixroute ens18
+       valid_lft forever preferred_lft forever
+    inet 192.168.1.2/24 brd 192.168.1.255 scope global noprefixroute ens18
- * Waiting in queue...
+       valid_lft forever preferred_lft forever
- * Waiting for authentication...
+    inet6 fe80::5223:aee1:998e:9f27/64 scope link noprefixroute
- * Waiting in queue...
+       valid_lft forever preferred_lft forever
- * Downloading packages...
+: virbr0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default qlen 1000
- * Requesting data...
+    link/ether 52:54:00:79:02:66 brd ff:ff:ff:ff:ff:ff
- * Testing changes...
+    inet 192.168.122.1/24 brd 192.168.122.255 scope global virbr0
- * Installing packages...
+       valid_lft forever preferred_lft forever
-Linux 4.18.0-305.3.1.el8.x86_64 (centos8.ittraining.loc)        29/06/21        _x86_64_(8 CPU)
+: virbr0-nic: <BROADCAST,MULTICAST> mtu 1500 qdisc fq_codel master virbr0 state DOWN group default qlen 1000
+    link/ether 52:54:00:79:02:66 brd ff:ff:ff:ff:ff:ff
-avg-cpu:  %user   %nice %system %iowait  %steal   %idle
-.03    0.00    0.03    0.01    0.00   99.93
-Device             tps    kB_read/s    kB_wrtn/s    kB_read    kB_wrtn
-sda               0.28         7.67         1.49     735338     142510
-sdb               0.00         0.03         0.00       2995          0
-scd0              0.00         0.00         0.00          2          0
-dm-0              0.26         7.25         1.55     694786     148837
-dm-1              0.00         0.02         0.00       2220          0
 </code>
-<code>
+===Command Line Switches===
-[root@centos8 ~]# iostat -d -x
-Linux 4.18.0-305.3.1.el8.x86_64 (centos8.ittraining.loc)        30/06/21        _x86_64_        (8 CPU)
-Device            r/s     w/s     rkB/s     wkB/s   rrqm/s   wrqm/s  %rrqm  %wrqm r_await w_await aqu-sz rareq-sz wareq-sz  svctm  %util
-sda              0.20    0.16     11.67      1.81     0.00     0.03   0.48  17.45    6.79   69.99   0.01    58.28    11.33   9.13   0.33
-sdb              0.00    0.00      0.02      0.00     0.00     0.00   0.00   0.00    0.13    0.00   0.00     8.81     0.00   0.51   0.00
-scd0             0.00    0.00      0.00      0.00     0.00     0.00   0.00   0.00    0.20    0.00   0.00     0.20     0.00   0.90   0.00
-dm-0             0.12    0.19      3.98      1.90     0.00     0.00   0.00   0.00    4.18   79.07   0.02    32.88    10.07  10.34   0.32
-dm-1             0.00    0.00      0.01      0.00     0.00     0.00   0.00   0.00    0.76    0.00   0.00    21.35     0.00   0.68   0.00
-</code>
 The command line switches of this command are:
 <code>
-[root@centos8 ~]# iostat --help
+[root@centos8 ~]# ip --help
-Usage: iostat [ options ] [ <interval> [ <count> ] ]
+Usage: ip [ OPTIONS ] OBJECT { COMMAND | help }
-Options are:
+       ip [ -force ] -batch filename
-[ -c ] [ -d ] [ -h ] [ -k | -m ] [ -N ] [ -s ] [ -t ] [ -V ] [ -x ] [ -y ] [ -z ]
+where  OBJECT := { link | address | addrlabel | route | rule | neigh | ntable |
-[ -j { ID | LABEL | PATH | UUID | ... } ] [ --human ] [ -o JSON ]
+                   tunnel | tuntap | maddress | mroute | mrule | monitor | xfrm |
-[ [ -H ] -g <group_name> ] [ -p [ <device> [,...] | ALL ] ]
+                   netns | l2tp | fou | macsec | tcp_metrics | token | netconf | ila |
-[ <device> [...] | ALL ]
+                   vrf | sr | nexthop | mptcp }
-</code>
+       OPTIONS := { -V[ersion] | -s[tatistics] | -d[etails] | -r[esolve] |
+                    -h[uman-readable] | -iec | -j[son] | -p[retty] |
-====3.4 - The hdparm Command====
+                    -f[amily] { inet | inet6 | mpls | bridge | link } |
+                    -4 | -6 | -I | -D | -M | -B | -0 |
-The hdparm command measures disk reads:
+                    -l[oops] { maximum-addr-flush-attempts } | -br[ief] |
+                    -o[neline] | -t[imestamp] | -ts[hort] | -b[atch] [filename] |
-<code>
+                    -rc[vbuf] [size] | -n[etns] name | -N[umeric] | -a[ll] |
-[root@centos8 ~]# hdparm -t /dev/sda
+                    -c[olor]}
-/dev/sda:
- Timing buffered disk reads: 1410 MB in  3.00 seconds = 469.98 MB/sec
 </code>
-====3.5 - La Commande vmstat====
+====1.6 - Manually Activating and Disactivating a Device====
-The **vmstat** commands shows memory, pagination and processor statistics:
+Two commands exist for this purpose:
 <code>
-[root@centos8 ~]# vmstat 1 10
+# nmcli device disconnect enp0s3
-procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu-----
+# nmcli device connect enp0s3
- r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
-  0      0 1765216   2256 866336    0    0     3     0    9   12  0  0 100  0  0
-  0      0 1765136   2256 866336    0    0     0     0   57   80  0  0 100  0  0
-  0      0 1765136   2256 866376    0    0     0     0   54   77  0  0 100  0  0
-  0      0 1765136   2256 866376    0    0     0     0   66  100  0  0 100  0  0
-  0      0 1765136   2256 866376    0    0     0     0  103  125  0  0 100  0  0
-  0      0 1765108   2256 866376    0    0     0     0   64   86  0  0 100  0  0
-  0      0 1765108   2256 866376    0    0     0     0   62   88  0  0 100  0  0
-  0      0 1765108   2256 866376    0    0     0     0   68   97  0  0 100  0  0
-  0      0 1765108   2256 866376    0    0     0     0   60   88  0  0 100  0  0
-  0      0 1765108   2256 866376    0    0     0     0  177  251  0  0 100  0  0
-</code>
-The command line switches of this command are:
-<code>
-[root@centos8 ~]# vmstat --help
-Usage:
- vmstat [options] [delay [count]]
-Options:
- -a, --active           active/inactive memory
- -f, --forks            number of forks since boot
- -m, --slabs            slabinfo
- -n, --one-header       do not redisplay header
- -s, --stats            event counter statistics
- -d, --disk             disk statistics
- -D, --disk-sum         summarize disk statistics
- -p, --partition <dev>  partition specific statistics
- -S, --unit <char>      define display unit
- -w, --wide             wide output
- -t, --timestamp        show timestamp
- -h, --help     display this help and exit
- -V, --version  output version information and exit
-For more details see vmstat(8).
 </code>
 <WRAP center round important 60%>
-**Important** : By default vmstat shows statistics from boot until current time.
+**Important** : Do **NOT** execute these two commands.
 </WRAP>
-====3.6 - The mpstat Command====
+====1.7 - Static Routing====
-La commande **mpstat** affiche des statistiques détaillées sur le CPU :
+===The ip Command===
-<code>
+To delete the 192.168.1.0 route, use the following command:
-[root@centos8 ~]# mpstat
-Linux 4.18.0-305.3.1.el8.x86_64 (centos8.ittraining.loc)        29/06/21        _x86_64_(8 CPU)
-:53:22     CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest  %gnice   %idle
-:53:22     all    0.03    0.00    0.01    0.02    0.01    0.01    0.00    0.00    0.00   99.92
-</code>
-If there are several CPU's in the system, statistics can be viewed by core and as an average:
 <code>
-[root@centos8 ~]# mpstat -P ALL
+[root@centos8 ~]# ip route
-Linux 4.18.0-305.3.1.el8.x86_64 (centos8.ittraining.loc)        29/06/21        _x86_64_(8 CPU)
+default via 10.0.2.1 dev ens18 proto static metric 100
+.0.2.0/24 dev ens18 proto kernel scope link src 10.0.2.46 metric 100
+.168.1.0/24 dev ens18 proto kernel scope link src 192.168.1.2 metric 100
+.168.122.0/24 dev virbr0 proto kernel scope link src 192.168.122.1 linkdown
-:54:28     CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest  %gnice   %idle
+root@centos8 ~]# ip route del 192.168.1.0/24 via 0.0.0.0
-:54:28     all    0.03    0.00    0.01    0.02    0.01    0.01    0.00    0.00    0.00   99.92
+[root@centos8 ~]# ip route
-:54:28       0    0.03    0.00    0.01    0.00    0.01    0.00    0.00    0.00    0.00   99.94
+default via 10.0.2.1 dev ens18 proto static metric 100
-:54:28       1    0.02    0.00    0.02    0.03    0.02    0.00    0.00    0.00    0.00   99.91
+.0.2.0/24 dev ens18 proto kernel scope link src 10.0.2.46 metric 100
-:54:28       2    0.02    0.00    0.01    0.01    0.01    0.04    0.00    0.00    0.00   99.90
+.168.122.0/24 dev virbr0 proto kernel scope link src 192.168.122.1 linkdown
-:54:28       3    0.01    0.00    0.01    0.02    0.00    0.00    0.00    0.00    0.00   99.95
-:54:28       4    0.05    0.00    0.02    0.03    0.01    0.00    0.00    0.00    0.00   99.88
-:54:28       5    0.03    0.01    0.01    0.02    0.01    0.00    0.00    0.00    0.00   99.92
-:54:28       6    0.02    0.00    0.02    0.01    0.01    0.00    0.00    0.00    0.00   99.95
-:54:28       7    0.02    0.00    0.01    0.01    0.01    0.00    0.00    0.00    0.00   99.94
 </code>
-Finally, mpstat is capable of showing statistics over time. In the following example you can see 5 data sets, one taken every 2 seconds:
+To add a route for the 192.168.1.0 network, use the following command:
 <code>
-[root@centos8 ~]# mpstat -P ALL 2 5
+[root@centos8 ~]# ip route add 192.168.1.0/24 via 10.0.2.1
-Linux 4.18.0-305.3.1.el8.x86_64 (centos8.ittraining.loc)        29/06/21        _x86_64_        (8 CPU)
+[root@centos8 ~]# ip route
+default via 10.0.2.1 dev ens18 proto static metric 100
-:55:11     CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest  %gnice   %idle
+.0.2.0/24 dev ens18 proto kernel scope link src 10.0.2.46 metric 100
-:55:13     all    0.00    0.00    0.00    0.00    0.00    0.00    0.06    0.00    0.00   99.94
+.168.1.0/24 via 10.0.2.1 dev ens18
-:55:13       0    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
+.168.122.0/24 dev virbr0 proto kernel scope link src 192.168.122.1 linkdown
-:55:13       1    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
-:55:13       2    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
-:55:13       3    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
-:55:13       4    0.00    0.00    0.00    0.00    0.00    0.00    0.50    0.00    0.00   99.50
-:55:13       5    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
-:55:13       6    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
-:55:13       7    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
-:55:13     CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest  %gnice   %idle
-:55:15     all    0.00    0.00    0.00    0.00    0.06    0.00    0.00    0.00    0.00   99.94
-:55:15       0    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
-:55:15       1    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
-:55:15       2    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
-:55:15       3    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
-:55:15       4    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
-:55:15       5    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
-:55:15       6    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
-:55:15       7    0.00    0.00    0.00    0.00    0.50    0.00    0.00    0.00    0.00   99.50
-:55:15     CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest  %gnice   %idle
-:55:17     all    0.00    0.00    0.00    0.00    0.06    0.00    0.00    0.00    0.00   99.94
-:55:17       0    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
-:55:17       1    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
-:55:17       2    0.00    0.00    0.00    0.00    0.50    0.00    0.00    0.00    0.00   99.50
-:55:17       3    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
-:55:17       4    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
-:55:17       5    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
-:55:17       6    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
-:55:17       7    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
-:55:17     CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest  %gnice   %idle
-:55:19     all    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
-:55:19       0    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
-:55:19       1    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
-:55:19       2    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
-:55:19       3    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
-:55:19       4    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
-:55:19       5    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
-:55:19       6    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
-:55:19       7    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
-:55:19     CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest  %gnice   %idle
-:55:21     all    0.06    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00   99.94
-:55:21       0    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
-:55:21       1    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
-:55:21       2    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
-:55:21       3    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
-:55:21       4    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
-:55:21       5    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
-:55:21       6    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
-:55:21       7    0.50    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00   99.50
-Average:     CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest  %gnice   %idle
-Average:     all    0.01    0.00    0.00    0.00    0.02    0.00    0.01    0.00    0.00   99.95
-Average:       0    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
-Average:       1    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
-Average:       2    0.00    0.00    0.00    0.00    0.10    0.00    0.00    0.00    0.00   99.90
-Average:       3    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
-Average:       4    0.00    0.00    0.00    0.00    0.00    0.00    0.10    0.00    0.00   99.90
-Average:       5    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
-Average:       6    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
-Average:       7    0.10    0.00    0.00    0.00    0.10    0.00    0.00    0.00    0.00   99.80
 </code>
-The command line switches of this command are:
+<WRAP center round important 60%>
+**Important** - The command used to add a default gateway is **ip route add default via //ip_address//**.
-<code>
+</WRAP>
-[root@centos8 ~]# mpstat --help
-Usage: mpstat [ options ] [ <interval> [ <count> ] ]
-Options are:
-[ -A ] [ -n ] [ -u ] [ -V ] [ -I { SUM | CPU | SCPU | ALL } ]
-[ -N { <node_list> | ALL } ] [ -o JSON ] [ -P { <cpu_list> | ALL } ]
-</code>
-====3.7 - The sar Command====
-The **sar** command can survey all system resources dependant upon the switch that is used. Several important switches are:
-^ Switch ^ Description ^
+===Disactivating/Activating Internal Routing on a Server===
-| -u | CPU usage in % |
-| -q | Number of processes in the process queue |
-| -r | Memory usage |
-| -w | Swap usage |
-| -p | Pagination usage |
-| -b | Buffer usage |
-| -d | Disk usage |
-The **/usr/lib64/sa/sadc** command is used to collect data:
+To disactivate internal routing between interfaces, use the following command:
 <code>
-[root@centos8 ~]# ls /usr/lib64/sa
+[root@centos8 ~]# cat /proc/sys/net/ipv4/ip_forward
-sa1  sa2  sadc
+[root@centos8 ~]# echo 0 > /proc/sys/net/ipv4/ip_forward
+[root@centos8 ~]# cat /proc/sys/net/ipv4/ip_forward
 </code>
-The **/usr/lib64/sa/sa1** script calls the **/usr/lib/sa/sadc** command and can use two switches:
+To activate internal routing between interfaces, use the following command:
-^ Switch ^ Description ^
-| -t | Interval |
-| -n | Count |
-The **/usr/lib64/sa/sa2** script also creates a log at **/var/log/sa/sar<dd>**, where <dd> is the day of the month.
 <code>
-[root@centos8 ~]# ls /var/log/sa/
+[root@centos8 ~]# echo 1 > /proc/sys/net/ipv4/ip_forward
-sa29  s
+[root@centos8 ~]# cat /proc/sys/net/ipv4/ip_forward
-ar29
 </code>
-Using CentOS / RHEL 8, the interval between collects is configured using systemd **timers** de systemd and not cron as was previously the case:
+=====LAB #2 - Diagnostics=====
-<code>
+====2.1 - ping====
-[root@centos8 ~]# cat /usr/lib/systemd/system/sysstat-collect.timer
-# /usr/lib/systemd/system/sysstat-collect.timer
-# (C) 2014 Tomasz Torcz <tomek@pipebreaker.pl>
-#
-# sysstat-11.7.3 systemd unit file:
-#        Activates activity collector every 10 minutes
-[Unit]
-Description=Run system activity accounting tool every 10 minutes
-[Timer]
-OnCalendar=*:00/10
-[Install]
-WantedBy=sysstat.service
-</code>
-The **OnCalendar** value indicates a collect every 10 minutes.
-To change this value, you need to create an **override** file in **/etc/systemd/system/** by using the **systemctl edit** command. You should never edit directly files in **/usr/lib/systemd/system** :
+To test whether a destination can be reached, use the **ping** command:
 <code>
-[root@centos8 ~]# systemctl edit sysstat-collect.timer
+[root@centos8 ~]# ping -c4 10.0.2.1
-[root@centos8 ~]# cat /etc/systemd/system/sysstat-collect.timer.d/override.conf
+PING 10.0.2.1 (10.0.2.1) 56(84) bytes of data.
-[Unit]
+bytes from 10.0.2.1: icmp_seq=1 ttl=64 time=0.104 ms
-Description=Run system activity accounting tool every 2 minutes
+bytes from 10.0.2.1: icmp_seq=2 ttl=64 time=0.325 ms
+bytes from 10.0.2.1: icmp_seq=3 ttl=64 time=0.250 ms
+bytes from 10.0.2.1: icmp_seq=4 ttl=64 time=0.123 ms
-[Timer]
+--- 10.0.2.1 ping statistics ---
-OnCalendar=
+packets transmitted, 4 received, 0% packet loss, time 3083ms
-OnCalendar=*:00/2
+rtt min/avg/max/mdev = 0.104/0.200/0.325/0.092 ms
-AccuracySec=0
 </code>
-<WRAP center round important 60%>
+===Command Line Switches===
-**Important** : Note the line **OnCalendar=** which is required to override the default value.
-</WRAP>
-Now check if the configuration has been applied:
+The command line switches of this command are:
 <code>
-[root@centos8 ~]# systemctl status sysstat-collect.timer
+[root@centos8 ~]# ping --help
-● sysstat-collect.timer - Run system activity accounting tool every 2 minutes
+ping: invalid option -- '-'
-   Loaded: loaded (/usr/lib/systemd/system/sysstat-collect.timer; enabled; vendor preset: disabled)
+Usage: ping [-aAbBdDfhLnOqrRUvV64] [-c count] [-i interval] [-I interface]
-  Drop-In: /etc/systemd/system/sysstat-collect.timer.d
+            [-m mark] [-M pmtudisc_option] [-l preload] [-p pattern] [-Q tos]
-           └─override.conf
+            [-s packetsize] [-S sndbuf] [-t ttl] [-T timestamp_option]
-   Active: active (waiting) since Tue 2021-06-29 06:16:04 EDT; 3h 2min ago
+            [-w deadline] [-W timeout] [hop1 ...] destination
-  Trigger: Tue 2021-06-29 09:20:00 EDT; 1min 19s left
+Usage: ping -6 [-aAbBdDfhLnOqrRUvV] [-c count] [-i interval] [-I interface]
+             [-l preload] [-m mark] [-M pmtudisc_option]
-Jun 29 06:16:04 centos8.ittraining.loc systemd[1]: Started Run system activity accounting tool every 10 minutes.
+             [-N nodeinfo_option] [-p pattern] [-Q tclass] [-s packetsize]
+             [-S sndbuf] [-t ttl] [-T timestamp_option] [-w deadline]
+             [-W timeout] destination
 </code>
-<code>
+====2.2 - netstat -i====
-[root@centos8 ~]# journalctl -g sysstat-collect.service
--- Logs begin at Mon 2021-06-28 02:04:10 EDT, end at Tue 2021-06-29 09:18:00 EDT. --
-Jun 29 06:20:33 centos8.ittraining.loc systemd[1]: sysstat-collect.service: Succeeded.
-Jun 29 06:26:29 centos8.ittraining.loc systemd[1]: sysstat-collect.service: Succeeded.
-Jun 29 06:30:33 centos8.ittraining.loc systemd[1]: sysstat-collect.service: Succeeded.
-Jun 29 06:40:33 centos8.ittraining.loc systemd[1]: sysstat-collect.service: Succeeded.
-Jun 29 06:50:33 centos8.ittraining.loc systemd[1]: sysstat-collect.service: Succeeded.
-Jun 29 07:00:33 centos8.ittraining.loc systemd[1]: sysstat-collect.service: Succeeded.
-Jun 29 07:10:33 centos8.ittraining.loc systemd[1]: sysstat-collect.service: Succeeded.
-Jun 29 07:20:33 centos8.ittraining.loc systemd[1]: sysstat-collect.service: Succeeded.
-Jun 29 07:30:33 centos8.ittraining.loc systemd[1]: sysstat-collect.service: Succeeded.
-Jun 29 07:40:33 centos8.ittraining.loc systemd[1]: sysstat-collect.service: Succeeded.
-Jun 29 07:50:33 centos8.ittraining.loc systemd[1]: sysstat-collect.service: Succeeded.
-Jun 29 07:53:56 centos8.ittraining.loc systemd[1]: sysstat-collect.service: Succeeded.
-Jun 29 07:54:00 centos8.ittraining.loc systemd[1]: sysstat-collect.service: Succeeded.
-Jun 29 07:56:00 centos8.ittraining.loc systemd[1]: sysstat-collect.service: Succeeded.
-Jun 29 07:58:00 centos8.ittraining.loc systemd[1]: sysstat-collect.service: Succeeded.
-Jun 29 08:00:00 centos8.ittraining.loc systemd[1]: sysstat-collect.service: Succeeded.
-...
-</code>
-Execute the sar command:
+To see networking statistics, use the **netstat** command:
 <code>
-[root@centos8 ~]# sar
+[root@centos8 ~]# netstat -i
-Linux 4.18.0-305.3.1.el8.x86_64 (centos8.ittraining.loc)        29/06/21        _x86_64_        (8 CPU)
+Kernel Interface table
+Iface             MTU    RX-OK RX-ERR RX-DRP RX-OVR    TX-OK TX-ERR TX-DRP TX-OVR Flg
-:16:04     LINUX RESTART      (8 CPU)
+ens18            1500   476056      0      0 0        363562      0      0      0 BMRU
+lo              65536    10936      0      0 0         10936      0      0      0 LRU
-:20:33        CPU     %user     %nice   %system   %iowait    %steal     %idle
+virbr0           1500        0      0      0 0             0      0      0      0 BMU
-:26:29        all      0.03      0.00      0.03      0.00      0.00     99.94
-:30:33        all      0.02      0.00      0.03      0.00      0.00     99.95
-:40:33        all      0.02      0.00      0.03      0.00      0.00     99.94
-:50:33        all      0.02      0.00      0.02      0.00      0.00     99.95
-:00:33        all      0.02      0.00      0.02      0.00      0.00     99.95
-:10:33        all      0.02      0.00      0.02      0.00      0.00     99.95
-:20:33        all      0.02      0.00      0.03      0.00      0.00     99.95
-:30:33        all      0.02      0.01      0.03      0.00      0.00     99.94
-:40:33        all      0.03      0.00      0.04      0.00      0.00     99.93
-:50:33        all      0.03      0.00      0.03      0.00      0.00     99.94
-:53:56        all      0.08      0.00      0.06      0.00      0.00     99.86
-:54:00        all      0.09      0.00      0.06      0.00      0.00     99.85
-Average:        all      0.03      0.00      0.03      0.00      0.00     99.94
-:55:44     LINUX RESTART      (8 CPU)
-:56:00        CPU     %user     %nice   %system   %iowait    %steal     %idle
-:58:00        all      0.03      0.00      0.03      0.00      0.00     99.94
-:00:00        all      0.02      0.00      0.04      0.00      0.00     99.94
-:02:00        all      0.02      0.00      0.03      0.00      0.00     99.94
-:04:00        all      0.02      0.00      0.03      0.00      0.00     99.95
-:06:00        all      0.02      0.00      0.03      0.00      0.00     99.95
-:08:00        all      0.02      0.00      0.04      0.00      0.00     99.94
-:10:00        all      0.02      0.00      0.03      0.00      0.00     99.95
-:12:00        all      0.03      0.00      0.03      0.00      0.00     99.95
-:14:00        all      0.02      0.00      0.03      0.01      0.00     99.94
-:16:00        all      0.02      0.00      0.03      0.00      0.00     99.95
-:18:00        all      0.02      0.00      0.03      0.00      0.00     99.95
-:20:00        all      0.02      0.00      0.04      0.00      0.00     99.94
-:22:00        all      0.02      0.00      0.03      0.00      0.00     99.95
-:24:00        all      0.02      0.00      0.02      0.00      0.00     99.95
-:26:00        all      0.02      0.00      0.03      0.00      0.00     99.95
-:28:00        all      0.02      0.00      0.04      0.00      0.00     99.94
-:30:00        all      0.02      0.05      0.05      0.00      0.00     99.87
-:32:00        all      0.02      0.00      0.04      0.00      0.00     99.94
-:34:00        all      0.02      0.00      0.04      0.00      0.00     99.94
-:36:00        all      0.03      0.00      0.04      0.00      0.00     99.94
-:38:00        all      0.02      0.00      0.04      0.00      0.00     99.94
-:40:00        all      0.02      0.00      0.04      0.00      0.00     99.94
-:42:00        all      0.02      0.00      0.03      0.00      0.00     99.94
-:44:00        all      0.03      0.00      0.03      0.00      0.00     99.94
-:46:00        all      0.02      0.00      0.03      0.00      0.00     99.94
-:48:00        all      0.03      0.00      0.03      0.00      0.00     99.95
-:50:00        all      0.02      0.00      0.04      0.00      0.00     99.94
-:52:00        all      0.02      0.00      0.06      0.00      0.00     99.92
-:54:00        all      0.02      0.00      0.03      0.00      0.00     99.95
-:56:00        all      0.02      0.00      0.04      0.00      0.00     99.94
-:58:00        all      0.02      0.00      0.02      0.00      0.00     99.96
-:00:00        all      0.07      0.00      0.05      0.00      0.00     99.88
-:02:00        all      0.02      0.00      0.04      0.00      0.00     99.94
-:04:00        all      0.02      0.00      0.03      0.00      0.00     99.95
-:06:00        all      0.02      0.00      0.04      0.00      0.00     99.94
-:08:00        all      0.02      0.00      0.04      0.00      0.00     99.94
-:10:00        all      0.02      0.00      0.03      0.00      0.00     99.95
-:12:00        all      0.02      0.00      0.03      0.00      0.00     99.94
-:12:00        CPU     %user     %nice   %system   %iowait    %steal     %idle
-:14:00        all      0.02      0.00      0.03      0.00      0.00     99.95
-:16:00        all      0.02      0.00      0.06      0.00      0.00     99.92
-:18:00        all      0.03      0.00      0.03      0.00      0.00     99.95
-:20:00        all      0.02      0.00      0.03      0.00      0.00     99.94
-Average:        all      0.02      0.00      0.03      0.00      0.00     99.94
 </code>
-===CPU Stats===
+===Command Line Switches===
-Use the -u switch:
+The command line switches of this command are:
 <code>
-[root@centos8 ~]# sar -u 5 3
+[root@centos8 ~]# netstat --help
-Linux 4.18.0-305.3.1.el8.x86_64 (centos8.ittraining.loc)        29/06/21        _x86_64_        (8 CPU)
+usage: netstat [-vWeenNcCF] [<Af>] -r         netstat {-V|--version|-h|--help}
+       netstat [-vWnNcaeol] [<Socket> ...]
+       netstat { [-vWeenNac] -I[<Iface>] | [-veenNac] -i | [-cnNe] -M | -s [-6tuw] } [delay]
-:22:52        CPU     %user     %nice   %system   %iowait    %steal     %idle
+        -r, --route              display routing table
-:22:57        all      0.03      0.00      0.03      0.00      0.00     99.95
+        -I, --interfaces=<Iface> display interface table for <Iface>
-:23:02        all      0.03      0.00      0.03      0.00      0.00     99.95
+        -i, --interfaces         display interface table
-:23:07        all      0.00      0.00      0.03      0.00      0.00     99.97
+        -g, --groups             display multicast group memberships
-Average:        all      0.02      0.00      0.03      0.00      0.00     99.96
+        -s, --statistics         display networking statistics (like SNMP)
-</code>
+        -M, --masquerade         display masqueraded connections
-More information can be shown by using the **ALL** argument:
+        -v, --verbose            be verbose
+        -W, --wide               don't truncate IP addresses
+        -n, --numeric            don't resolve names
+        --numeric-hosts          don't resolve host names
+        --numeric-ports          don't resolve port names
+        --numeric-users          don't resolve user names
+        -N, --symbolic           resolve hardware names
+        -e, --extend             display other/more information
+        -p, --programs           display PID/Program name for sockets
+        -o, --timers             display timers
+        -c, --continuous         continuous listing
-<code>
+        -l, --listening          display listening server sockets
-[root@centos8 ~]# sar -u ALL 5 3
+        -a, --all                display all sockets (default: connected)
-Linux 4.18.0-305.3.1.el8.x86_64 (centos8.ittraining.loc)        29/06/21        _x86_64_(8 CPU)
+        -F, --fib                display Forwarding Information Base (default)
+        -C, --cache              display routing cache instead of FIB
+        -Z, --context            display SELinux security context for sockets
-:49:14        CPU      %usr     %nice      %sys   %iowait    %steal      %irq     %soft    %guest    %gnice     %idle
+  <Socket>={-t|--tcp} {-u|--udp} {-U|--udplite} {-S|--sctp} {-w|--raw}
-:49:19        all      0.03      0.00      0.00      0.00      0.00      0.03      0.00      0.00      0.00     99.95
+           {-x|--unix} --ax25 --ipx --netrom
-:49:24        all      0.03      0.00      0.03      0.00      0.00      0.10      0.05      0.00      0.00     99.80
+  <AF>=Use '-6|-4' or '-A <af>' or '--<af>'; default: inet
-:49:29        all      0.00      0.00      0.00      0.25      0.00      0.10      0.05      0.00      0.00     99.60
+  List of possible address families (which support routing):
-Average:        all      0.02      0.00      0.01      0.08      0.00      0.08      0.03      0.00      0.00     99.78
+    inet (DARPA Internet) inet6 (IPv6) ax25 (AMPR AX.25)
+    netrom (AMPR NET/ROM) ipx (Novell IPX) ddp (Appletalk DDP)
+    x25 (CCITT X.25)
 </code>
-To see the statistics from a specific core, use the **-P** switch:
+====2.3 - traceroute====
-<code>
+This command is used to discover the route taken to reach a specified destination:
-[root@centos8 ~]# sar -u -P 1 5 3
-Linux 4.18.0-305.3.1.el8.x86_64 (centos8.ittraining.loc)        29/06/21        _x86_64_        (8 CPU)
-:51:52        CPU     %user     %nice   %system   %iowait    %steal     %idle
-:51:57          1      0.00      0.00      0.00      0.00      0.00    100.00
-:52:02          1      0.20      0.00      0.00      0.00      0.00     99.80
-:52:07          1      0.00      0.00      0.00      0.00      0.00    100.00
-Average:          1      0.07      0.00      0.00      0.00      0.00     99.93
-[root@centos8 ~]# sar -u -P 5 5 3
-Linux 4.18.0-305.3.1.el8.x86_64 (centos8.ittraining.loc)        29/06/21        _x86_64_        (8 CPU)
-:52:16        CPU     %user     %nice   %system   %iowait    %steal     %idle
-:52:21          5      0.00      0.00      0.00      0.00      0.00    100.00
-:52:26          5      0.00      0.00      0.00      0.00      0.00    100.00
-:52:31          5      0.00      0.00      0.00      0.00      0.00    100.00
-Average:          5      0.00      0.00      0.00      0.00      0.00    100.00
-</code>
-===Memory and Swap Statistics===
-Use the **-r** switch to see memory statistics:
 <code>
-[root@centos8 ~]# sar -r 5 3
+[root@centos8 ~]# traceroute www.ittraining.network
-Linux 4.18.0-305.3.1.el8.x86_64 (centos8.ittraining.loc)        30/06/21        _x86_64_(8 CPU)
+bash: traceroute: command not found...
+Install package 'traceroute' to provide command 'traceroute'? [N/y] y
-:33:32    kbmemfree   kbavail kbmemused  %memused kbbuffers  kbcached  kbcommit   %commit  kbactive   kbinact   kbdirty
-:33:37      1647240   2297232   2177792     56.94      3356    827396   5096432     70.94    359072   1486368         0
-:33:42      1647232   2297224   2177800     56.94      3356    827396   5095788     70.93    359072   1486300         0
-:33:47      1647232   2297224   2177800     56.94      3356    827396   5095788     70.93    359072   1486376         0
-Average:      1647235   2297227   2177797     56.94      3356    827396   5096003     70.94    359072   1486348         0
-</code>
-Use the **-S** switch to see swap statistics:
+ * Waiting in queue...
+The following packages have to be installed:
+ traceroute-3:2.1.0-6.el8.x86_64        Traces the route taken by packets over an IPv4/IPv6 network
+Proceed with changes? [N/y] y
-<code>
-[root@centos8 ~]# sar -S 5 3
-Linux 4.18.0-305.3.1.el8.x86_64 (centos8.ittraining.loc)        30/06/21        _x86_64_(8 CPU)
-:31:58    kbswpfree kbswpused  %swpused  kbswpcad   %swpcad
+ * Waiting in queue...
-:32:03      3358716         0      0.00         0      0.00
+ * Waiting for authentication...
-:32:08      3358716         0      0.00         0      0.00
+ * Waiting in queue...
-:32:13      3358716         0      0.00         0      0.00
+ * Downloading packages...
-Average:      3358716         0      0.00         0      0.00
+ * Requesting data...
+ * Testing changes...
+ * Installing packages...
+traceroute to www.ittraining.network (109.228.56.52), 30 hops max, 60 byte packets
+  _gateway (10.0.2.1)  0.132 ms  0.101 ms  0.078 ms
+  79.137.68.252 (79.137.68.252)  0.542 ms  0.656 ms  0.809 ms
+  10.50.24.61 (10.50.24.61)  0.238 ms  0.219 ms 10.50.24.60 (10.50.24.60)  0.239 ms
+  10.50.0.16 (10.50.0.16)  0.172 ms 10.50.0.22 (10.50.0.22)  0.194 ms  0.173 ms
+  10.73.248.192 (10.73.248.192)  0.766 ms 10.73.248.194 (10.73.248.194)  0.730 ms 10.73.248.192 (10.73.248.192)  0.757 ms
+  waw-wa2-sbb1-nc5.pl.eu (91.121.131.150)  1.102 ms  1.396 ms  1.099 ms
+  fra-fr5-sbb1-nc5.de.eu (213.251.128.113)  18.309 ms fra-fr5-sbb2-nc5.de.eu (54.36.50.116)  21.881 ms fra-fr5-sbb1-nc5.de.eu (213.251.128.113)  16.764 ms
+  10.200.0.6 (10.200.0.6)  20.922 ms 10.200.0.0 (10.200.0.0)  16.959 ms 10.200.0.4 (10.200.0.4)  21.143 ms
+  decix.bb-a.fra3.fra.de.oneandone.net (80.81.192.123)  18.789 ms decix.bb-c.act.fra.de.oneandone.net (80.81.193.123)  20.310 ms decix.bb-a.fra3.fra.de.oneandone.net (80.81.192.123)  18.693 ms
+  ae-14.bb-b.fr7.fra.de.oneandone.net (212.227.120.149)  22.222 ms  22.206 ms  22.257 ms
+  port-channel-3.gw-ngcs-1.dc1.con.glo.gb.oneandone.net (88.208.255.131)  39.660 ms  39.679 ms ae-19.bb-b.thn.lon.gb.oneandone.net (212.227.120.33)  33.973 ms
+  109.228.63.209 (109.228.63.209)  37.363 ms port-channel-3.gw-ngcs-1.dc1.con.glo.gb.oneandone.net (88.208.255.131)  39.534 ms 109.228.63.209 (109.228.63.209)  37.901 ms
+  * 109.228.63.209 (109.228.63.209)  38.014 ms  37.991 ms
+  * * *
+  * * *
+  * * *
+  * * *
+  * * *
+  * * *
+  * * *
+  * * *
+  * * *
+  * * *
+  * * *
+  * * *
+  * * *
+  * * *
+  * * *
+  * * *^C
 </code>
-===I/O Statistics===
+===Command Line Switches===
-Use the **-b** switch:
+The command line switches of this command are:
 <code>
-[root@centos8 ~]# sar -b 5 3
+[root@centos8 ~]# traceroute --help
-Linux 4.18.0-305.3.1.el8.x86_64 (centos8.ittraining.loc)        29/06/21        _x86_64_        (8 CPU)
+Usage:
+  traceroute [ -46dFITnreAUDV ] [ -f first_ttl ] [ -g gate,... ] [ -i device ] [ -m max_ttl ] [ -N squeries ] [ -p port ] [ -t tos ] [ -l flow_label ] [ -w MAX,HERE,NEAR ] [ -q nqueries ] [ -s src_addr ] [ -z sendwait ] [ --fwmark=num ] host [ packetlen ]
+Options:
+  -4                          Use IPv4
+  -6                          Use IPv6
+  -d  --debug                 Enable socket level debugging
+  -F  --dont-fragment         Do not fragment packets
+  -f first_ttl  --first=first_ttl
+                              Start from the first_ttl hop (instead from 1)
+  -g gate,...  --gateway=gate,...
+                              Route packets through the specified gateway
+                              (maximum 8 for IPv4 and 127 for IPv6)
+  -I  --icmp                  Use ICMP ECHO for tracerouting
+  -T  --tcp                   Use TCP SYN for tracerouting (default port is 80)
+  -i device  --interface=device
+                              Specify a network interface to operate with
+  -m max_ttl  --max-hops=max_ttl
+                              Set the max number of hops (max TTL to be
+                              reached). Default is 30
+  -N squeries  --sim-queries=squeries
+                              Set the number of probes to be tried
+                              simultaneously (default is 16)
+  -n                          Do not resolve IP addresses to their domain names
+  -p port  --port=port        Set the destination port to use. It is either
+                              initial udp port value for "default" method
+                              (incremented by each probe, default is 33434), or
+                              initial seq for "icmp" (incremented as well,
+                              default from 1), or some constant destination
+                              port for other methods (with default of 80 for
+                              "tcp", 53 for "udp", etc.)
+  -t tos  --tos=tos           Set the TOS (IPv4 type of service) or TC (IPv6
+                              traffic class) value for outgoing packets
+  -l flow_label  --flowlabel=flow_label
+                              Use specified flow_label for IPv6 packets
+  -w MAX,HERE,NEAR  --wait=MAX,HERE,NEAR
+                              Wait for a probe no more than HERE (default 3)
+                              times longer than a response from the same hop,
+                              or no more than NEAR (default 10) times than some
+                              next hop, or MAX (default 5.0) seconds (float
+                              point values allowed too)
+  -q nqueries  --queries=nqueries
+                              Set the number of probes per each hop. Default is
+
+  -r                          Bypass the normal routing and send directly to a
+                              host on an attached network
+  -s src_addr  --source=src_addr
+                              Use source src_addr for outgoing packets
+  -z sendwait  --sendwait=sendwait
+                              Minimal time interval between probes (default 0).
+                              If the value is more than 10, then it specifies a
+                              number in milliseconds, else it is a number of
+                              seconds (float point values allowed too)
+  -e  --extensions            Show ICMP extensions (if present), including MPLS
+  -A  --as-path-lookups       Perform AS path lookups in routing registries and
+                              print results directly after the corresponding
+                              addresses
+  -M name  --module=name      Use specified module (either builtin or external)
+                              for traceroute operations. Most methods have
+                              their shortcuts (`-I' means `-M icmp' etc.)
+  -O OPTS,...  --options=OPTS,...
+                              Use module-specific option OPTS for the
+                              traceroute module. Several OPTS allowed,
+                              separated by comma. If OPTS is "help", print info
+                              about available options
+  --sport=num                 Use source port num for outgoing packets. Implies
+                              `-N 1'
+  --fwmark=num                Set firewall mark for outgoing packets
+  -U  --udp                   Use UDP to particular port for tracerouting
+                              (instead of increasing the port per each probe),
+                              default port is 53
+  -UL                         Use UDPLITE for tracerouting (default dest port
+                              is 53)
+  -D  --dccp                  Use DCCP Request for tracerouting (default port
+                              is 33434)
+  -P prot  --protocol=prot    Use raw packet of protocol prot for tracerouting
+  --mtu                       Discover MTU along the path being traced. Implies
+                              `-F -N 1'
+  --back                      Guess the number of hops in the backward path and
+                              print if it differs
+  -V  --version               Print version info and exit
+  --help                      Read this help and exit
-:24:49          tps      rtps      wtps   bread/s   bwrtn/s
+Arguments:
-:24:54         0.00      0.00      0.00      0.00      0.00
++     host          The host to traceroute to
-:24:59         1.20      0.00      1.20      0.00     20.20
+      packetlen     The full packet length (default is the length of an IP
-:25:04         0.00      0.00      0.00      0.00      0.00
+                    header plus 40). Can be ignored or increased to a minimal
-Average:         0.40      0.00      0.40      0.00      6.73
+                    allowed value
 </code>
-===Disk I/O Statistics===
+===== LAB #3 - SSH====
-Use the **-d** switch:
+====3.1 - Presentation====
-<code>
+There are two types of SSH.
-[root@centos8 ~]# sar -d 5 3
-Linux 4.18.0-305.3.1.el8.x86_64 (centos8.ittraining.loc)        29/06/21        _x86_64_        (8 CPU)
-:25:45          DEV       tps     rkB/s     wkB/s   areq-sz    aqu-sz     await     svctm     %util
+===SSH-1===
-:25:50       dev8-0      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
-:25:50      dev8-16      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
-:25:50      dev11-0      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
-:25:50     dev253-0      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
-:25:50     dev253-1      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
-:25:50          DEV       tps     rkB/s     wkB/s   areq-sz    aqu-sz     await     svctm     %util
+To authenticate there are six possible methods:
-:25:55       dev8-0      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
-:25:55      dev8-16      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
-:25:55      dev11-0      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
-:25:55     dev253-0      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
-:25:55     dev253-1      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
-:25:55          DEV       tps     rkB/s     wkB/s   areq-sz    aqu-sz     await     svctm     %util
+  * **Kerberos**,
-:26:00       dev8-0      0.60      0.00      0.30      0.50      0.01     13.00     13.00      0.78
+  * **Rhosts**,
-:26:00      dev8-16      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
+  * **%%RhostsRSA%%**,
-:26:00      dev11-0      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
+  * **Asymetric Keys**,
-:26:00     dev253-0      0.60      0.00      0.50      0.83      0.01     12.67     13.00      0.78
+  * **TIS**,
-:26:00     dev253-1      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
+  * **Password**.
-Average:          DEV       tps     rkB/s     wkB/s   areq-sz    aqu-sz     await     svctm     %util
+==SSH-2==
-Average:       dev8-0      0.20      0.00      0.10      0.50      0.00     13.00     13.00      0.26
-Average:      dev8-16      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
-Average:      dev11-0      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
-Average:     dev253-0      0.20      0.00      0.17      0.83      0.00     12.67     13.00      0.26
-Average:     dev253-1      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
-</code>
-The **DEV** column identifies the disks by their major/minor numbers. To see the names of the disks add the, **-p** switch:
+To authenticate there are three possible methods:
-<code>
+  * **Asymetric Keys**,
-[root@centos8 ~]# sar -p -d 5 3
+  * **%%RhostsRSA%%**,
-Linux 4.18.0-305.3.1.el8.x86_64 (centos8.ittraining.loc)        30/06/21        _x86_64_        (8 CPU)
+  * **Password**
-:48:32          DEV       tps     rkB/s     wkB/s   areq-sz    aqu-sz     await     svctm     %util
+===Command Line Switches===
-:48:37          sda      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
-:48:37          sdb      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
-:48:37          sr0      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
-:48:37    cl_centos8-root      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
-:48:37    cl_centos8-swap      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
-:48:37          DEV       tps     rkB/s     wkB/s   areq-sz    aqu-sz     await     svctm     %util
-:48:42          sda      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
-:48:42          sdb      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
-:48:42          sr0      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
-:48:42    cl_centos8-root      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
-:48:42    cl_centos8-swap      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
-:48:42          DEV       tps     rkB/s     wkB/s   areq-sz    aqu-sz     await     svctm     %util
-:48:47          sda      0.40      0.00      0.40      1.00      0.02     56.00     56.50      2.26
-:48:47          sdb      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
-:48:47          sr0      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
-:48:47    cl_centos8-root      0.40      0.00      0.80      2.00      0.02     56.00     56.50      2.26
-:48:47    cl_centos8-swap      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
-Average:          DEV       tps     rkB/s     wkB/s   areq-sz    aqu-sz     await     svctm     %util
-Average:          sda      0.13      0.00      0.13      1.00      0.01     56.00     56.50      0.75
-Average:          sdb      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
-Average:          sr0      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
-Average:    cl_centos8-root      0.13      0.00      0.27      2.00      0.01     56.00     56.50      0.75
-Average:    cl_centos8-swap      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
-</code>
 The command line switches of this command are:
 <code>
-[root@centos8 ~]# sar --help
+[root@centos8 ~]# ssh --help
-Usage: sar [ options ] [ <interval> [ <count> ] ]
+unknown option -- -
-Main options and reports (report name between square brackets):
+usage: ssh [-46AaCfGgKkMNnqsTtVvXxYy] [-B bind_interface]
-        -B      Paging statistics [A_PAGE]
+           [-b bind_address] [-c cipher_spec] [-D [bind_address:]port]
-        -b      I/O and transfer rate statistics [A_IO]
+           [-E log_file] [-e escape_char] [-F configfile] [-I pkcs11]
-        -d      Block devices statistics [A_DISK]
+           [-i identity_file] [-J [user@]host[:port]] [-L address]
-        -F [ MOUNT ]
+           [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port]
-                Filesystems statistics [A_FS]
+           [-Q query_option] [-R address] [-S ctl_path] [-W host:port]
-        -H      Hugepages utilization statistics [A_HUGE]
+           [-w local_tun[:remote_tun]] destination [command]
-        -I { <int_list> | SUM | ALL }
-                Interrupts statistics [A_IRQ]
-        -m { <keyword> [,...] | ALL }
-                Power management statistics [A_PWR_...]
-                Keywords are:
-                CPU     CPU instantaneous clock frequency
-                FAN     Fans speed
-                FREQ    CPU average clock frequency
-                IN      Voltage inputs
-                TEMP    Devices temperature
-                USB     USB devices plugged into the system
-        -n { <keyword> [,...] | ALL }
-                Network statistics [A_NET_...]
-                Keywords are:
-                DEV     Network interfaces
-                EDEV    Network interfaces (errors)
-                NFS     NFS client
-                NFSD    NFS server
-                SOCK    Sockets (v4)
-                IP      IP traffic      (v4)
-                EIP     IP traffic      (v4) (errors)
-                ICMP    ICMP traffic    (v4)
-                EICMP   ICMP traffic    (v4) (errors)
-                TCP     TCP traffic     (v4)
-                ETCP    TCP traffic     (v4) (errors)
-                UDP     UDP traffic     (v4)
-                SOCK6   Sockets (v6)
-                IP6     IP traffic      (v6)
-                EIP6    IP traffic      (v6) (errors)
-                ICMP6   ICMP traffic    (v6)
-                EICMP6  ICMP traffic    (v6) (errors)
-                UDP6    UDP traffic     (v6)
-                FC      Fibre channel HBAs
-                SOFT    Software-based network processing
-        -q      Queue length and load average statistics [A_QUEUE]
-        -r [ ALL ]
-                Memory utilization statistics [A_MEMORY]
-        -S      Swap space utilization statistics [A_MEMORY]
-        -u [ ALL ]
-                CPU utilization statistics [A_CPU]
-        -v      Kernel tables statistics [A_KTABLES]
-        -W      Swapping statistics [A_SWAP]
-        -w      Task creation and system switching statistics [A_PCSW]
-        -y      TTY devices statistics [A_SERIAL]
 </code>
-=====USB Modules=====
+====3.2 - Configuring the Server====
-The Universal Serial Bus can offer data transfer speeds of upto 480Mb/s for version 2.0 and upto 4.8 Gb/s for version 3.0. Under Linux the USB modules are:
+The server is configured by editing the **/etc/ssh/sshd_config** file:
-^ USB Version ^ Module ^ Name ^
+<code>
-|  1.0\1.1  | **UHCI** | //Universal Controller Host Interface// |
+[root@centos8 ~]# cat /etc/ssh/sshd_config
-|  :::  | **OHCI** | //Open Controller Host Interface// |
+#       $OpenBSD: sshd_config,v 1.103 2018/04/09 20:41:22 tj Exp $
-|  2.0  | **EHCI** | //Enhanced Host Controller Interface// |
-|  3.0  | **XHCI** | //Extensible Host Controller Interface// |
-The following table shows a list of commonly used USB modules:
+# This is the sshd server system-wide configuration file.  See
+# sshd_config(5) for more information.
-^ Module ^ Peripheral ^
+# This sshd was compiled with PATH=/usr/local/bin:/usr/bin:/usr/local/sbin:/usr/sbin
-|  **usb_storage**  | Block devices |
-|  **usbhid**  | Human Interface Device |
-|  **snd-usb-audio**  | Sound cards |
-|  **usbvidéo**  | Video acquisition cards |
-|  **irda-usb**  | IR peripherals |
-|  **usbnet**  | NICs |
-These modules can be loaded by any one of the following:
+# The strategy used for options in the default sshd_config shipped with
+# OpenSSH is to specify options with their default value where
+# possible, but leave them commented.  Uncommented options override the
+# default value.
-  * Initramfs,
+# If you want to change the port on a SELinux system, you have to tell
-  * The init process,
+# SELinux about this change.
-  * kmod by using the **/lib/modules/2.6.32-358.23.2.el6.i686/modules.usbmap** file,
+# semanage port -a -t ssh_port_t -p tcp #PORTNUMBER
-  * udev,
-  * manually.
-=====udev=====
-Since the 2.6 Kernel series, Linux capable of **hotplugging**. Linux uses three componants to manage hotplugging:
-  * Udev,
-  * HAL,
-  * Dbus.
-The roles of each componant are as follows:
-  * Udev dynamically creates/deletes nodes in the **/dev** directory,
-  * HAL obtains information from udev, creates a files in XML format representing the peripheral and then informs Nautilus by using Dbus,
-  * Dbus acts as a system bus and is used for inter-process communication.
-When Linux is booted, udev plays an important role:
-  * at boot **tmpfs** is mounted on /dev,
-  * udev copies any statically configured nodes from **/lib/udev/devices** to /dev,
-  * the **udevd** daemon collects **uevents** from the kernel and looks for anappropriate rule in the **/lib/udev/rules.d/** directory,
-  * udev creates the nodes and any required symbolic links specified in the rule previously identified,
-  * udev stores in RAM the rules from **/lib/udev/rules.d/*.rules**,
-  * when a change occurs udev updates the the rules in the RAM.
-udev uses the **sysfs** filesystem mounted on /sys which renders the peripherals visible to udev in user space. For example when a USB stick is inserted, udev creates **/dev/sdb1** automatically
-The main configuration file for udev is **/etc/udev/udev.conf** :
-<code>
-[root@centos8 ~]# cat /etc/udev/udev.conf
-# see udev.conf(5) for details
 #
-# udevd is also started in the initrd.  When this file is modified you might
+#Port 22
-# also want to rebuild the initrd, so that it will include the modified configuration.
+#AddressFamily any
+#ListenAddress 0.0.0.0
+#ListenAddress ::
-#udev_log="info"
+HostKey /etc/ssh/ssh_host_rsa_key
-</code>
+HostKey /etc/ssh/ssh_host_ecdsa_key
+HostKey /etc/ssh/ssh_host_ed25519_key
-Rules files can be foud in **/lib/udev/rules.d/** :
+# Ciphers and keying
+#RekeyLimit default none
-<code>
+# This system is following system-wide crypto policy. The changes to
-[root@centos8 ~]# ls /lib/udev/rules.d/
+# crypto properties (Ciphers, MACs, ...) will not have any effect here.
--md-raid-creating.rules              70-uaccess.rules
+# They will be overridden by command-line options passed to the server
--dm.rules                            70-wacom.rules
+# on command line.
--dm-lvm.rules                        71-biosdevname.rules
+# Please, check manual pages for update-crypto-policies(8) and sshd_config(5).
--dm-mpath.rules                      71-nvmf-iopolicy-netapp.rules
--dm-parts.rules                      71-prefixdevname.rules
--dm-disk.rules                       71-seat.rules
--usbmuxd.rules                       73-idrac.rules
--elevator.rules                      73-seat-late.rules
--libgphoto2.rules                    75-net-description.rules
--redhat.rules                        75-probe_mtd.rules
--usb-blacklist.rules                 75-rdma-description.rules
--usb_modeswitch.rules                77-mm-cinterion-port-types.rules
--udev-default.rules                  77-mm-dell-port-types.rules
--alias-kmsg.rules                    77-mm-ericsson-mbm.rules
--block.rules                         77-mm-fibocom-port-types.rules
--cdrom_id.rules                      77-mm-haier-port-types.rules
--drm.rules                           77-mm-huawei-net-port-types.rules
--evdev.rules                         77-mm-longcheer-port-types.rules
--fido-id.rules                       77-mm-mtk-port-types.rules
--input-id.rules                      77-mm-nokia-port-types.rules
--libfprint-2-autosuspend.rules       77-mm-pcmcia-device-blacklist.rules
--net.rules                           77-mm-quectel-port-types.rules
--persistent-alsa.rules               77-mm-sierra.rules
--persistent-input.rules              77-mm-simtech-port-types.rules
--persistent-storage.rules            77-mm-telit-port-types.rules
--persistent-storage-tape.rules       77-mm-ublox-port-types.rules
--persistent-v4l.rules                77-mm-usb-device-blacklist.rules
--raw.rules                           77-mm-usb-serial-adapters-greylist.rules
--rdma-ndd.rules                      77-mm-x22x-port-types.rules
--rdma-persistent-naming.rules        77-mm-zte-port-types.rules
--sensor.rules                        78-sound-card.rules
--serial.rules                        80-drivers.rules
--tpm-udev.rules                      80-iio-sensor-proxy.rules
--gdm.rules                           80-libinput-device-groups.rules
--gnome-bluetooth-rfkill.rules        80-mm-candidate.rules
--gnome-settings-daemon-rfkill.rules  80-net-setup-link.rules
--scsi-sg3_id.rules                   80-udisks2.rules
--multipath.rules                     81-kvm-rhel.rules
--fc-wwpn-id.rules                    84-nm-drivers.rules
--md-raid-arrays.rules                85-nm-unmanaged.rules
--scsi-sg3_symlink.rules              85-regulatory.rules
--btrfs.rules                         90-alsa-restore.rules
--md-raid-assembly.rules              90-bolt.rules
--libwacom.rules                      90-fwupd-devices.rules
--md-incremental.rules              Limiter les Ressources  90-iprutils.rules
--sane-backends.rules                 90-libinput-fuzz-override.rules
--kpartx.rules                        90-nm-thunderbolt.rules
--del-part-nodes.rules                90-pulseaudio.rules
--btattach-bcm.rules                  90-rdma-hw-modules.rules
--cd-sensors.rules                    90-rdma-ulp-modules.rules
--dm-lvm-metad.rules                  90-rdma-umad.rules
--libmtp.rules                        90-vconsole.rules
--md-clustered-confirm-device.rules   91-drm-modeset.rules
--hypervfcopy.rules                   95-cd-devices.rules
--hypervkvp.rules                     95-dm-notify.rules
--hypervvss.rules                     95-upower-csr.rules
--joystick.rules                      95-upower-hid.rules
--mouse.rules                         95-upower-wup.rules
--nvmf-autoconnect.rules              98-kexec.rules
--power-switch.rules                  99-qemu-guest-agent.rules
--printers.rules                      99-systemd.rules
--spice-vdagentd.rules                99-vmware-scsi-udev.rules
--touchpad.rules
-</code>
-<WRAP center round important 60%>
+# Logging
-**Important** : You can create your own rules by putting them in the **99-local.rules** file.
+#SyslogFacility AUTH
-</WRAP>
+SyslogFacility AUTHPRIV
+#LogLevel INFO
-The default udev rule file is **50-udev-default.rules**:
+# Authentication:
-<code>
+#LoginGraceTime 2m
-[root@centos8 ~]# cat /lib/udev/rules.d/50-udev-default.rules | more
+PermitRootLogin yes
-# do not edit this file, it will be overwritten on update
+#StrictModes yes
+#MaxAuthTries 6
+#MaxSessions 10
-# run a command on remove events
+#PubkeyAuthentication yes
-ACTION=="remove", ENV{REMOVE_CMD}!="", RUN+="$env{REMOVE_CMD}"
-ACTION=="remove", GOTO="default_end"
-SUBSYSTEM=="virtio-ports", KERNEL=="vport*", ATTR{name}=="?*", SYMLINK+="virtio-ports/$attr{name}"
+# The default is to check both .ssh/authorized_keys and .ssh/authorized_keys2
+# but this is overridden so installations will only check .ssh/authorized_keys
+AuthorizedKeysFile      .ssh/authorized_keys
-# select "system RTC" or just use the first one
+#AuthorizedPrincipalsFile none
-SUBSYSTEM=="rtc", ATTR{hctosys}=="1", SYMLINK+="rtc"
-SUBSYSTEM=="rtc", KERNEL=="rtc0", SYMLINK+="rtc", OPTIONS+="link_priority=-100"
-SUBSYSTEM=="usb", ENV{DEVTYPE}=="usb_device", IMPORT{builtin}="usb_id", IMPORT{builtin}="hwdb --subsystem=usb"
+#AuthorizedKeysCommand none
-ENV{MODALIAS}!="", IMPORT{builtin}="hwdb --subsystem=$env{SUBSYSTEM}"
+#AuthorizedKeysCommandUser nobody
-ACTION!="add", GOTO="default_end"
+# For this to work you will also need host keys in /etc/ssh/ssh_known_hosts
+#HostbasedAuthentication no
+# Change to yes if you don't trust ~/.ssh/known_hosts for
+# HostbasedAuthentication
+#IgnoreUserKnownHosts no
+# Don't read the user's ~/.rhosts and ~/.shosts files
+#IgnoreRhosts yes
-SUBSYSTEM=="tty", KERNEL=="ptmx", GROUP="tty", MODE="0666"
+# To disable tunneled clear text passwords, change to no here!
-SUBSYSTEM=="tty", KERNEL=="tty", GROUP="tty", MODE="0666"
+#PasswordAuthentication yes
-SUBSYSTEM=="tty", KERNEL=="tty[0-9]*", GROUP="tty", MODE="0620"
+#PermitEmptyPasswords no
-SUBSYSTEM=="tty", KERNEL=="sclp_line[0-9]*", GROUP="tty", MODE="0620"
+PasswordAuthentication yes
-SUBSYSTEM=="tty", KERNEL=="ttysclp[0-9]*", GROUP="tty", MODE="0620"
-SUBSYSTEM=="tty", KERNEL=="3270/tty[0-9]*", GROUP="tty", MODE="0620"
-SUBSYSTEM=="vc", KERNEL=="vcs*|vcsa*", GROUP="tty"
-KERNEL=="tty[A-Z]*[0-9]|ttymxc[0-9]*|pppox[0-9]*|ircomm[0-9]*|noz[0-9]*|rfcomm[0-9]*", GROUP="dialout"
-SUBSYSTEM=="mem", KERNEL=="mem|kmem|port", GROUP="kmem", MODE="0640"
+# Change to no to disable s/key passwords
+#ChallengeResponseAuthentication yes
+ChallengeResponseAuthentication no
-SUBSYSTEM=="input", GROUP="input"
+# Kerberos options
-SUBSYSTEM=="input", KERNEL=="js[0-9]*", MODE="0664"
+#KerberosAuthentication no
+#KerberosOrLocalPasswd yes
+#KerberosTicketCleanup yes
+#KerberosGetAFSToken no
+#KerberosUseKuserok yes
-SUBSYSTEM=="video4linux", GROUP="video"
+# GSSAPI options
-SUBSYSTEM=="graphics", GROUP="video"
+GSSAPIAuthentication yes
-SUBSYSTEM=="drm", KERNEL!="renderD*", GROUP="video"
+GSSAPICleanupCredentials no
-SUBSYSTEM=="dvb", GROUP="video"
+#GSSAPIStrictAcceptorCheck yes
-SUBSYSTEM=="media", GROUP="video"
+#GSSAPIKeyExchange no
-SUBSYSTEM=="cec", GROUP="video"
+#GSSAPIEnablek5users no
-SUBSYSTEM=="drm", KERNEL=="renderD*", GROUP="render", MODE="0666"
+# Set this to 'yes' to enable PAM authentication, account processing,
-SUBSYSTEM=="kfd", GROUP="render", MODE="0666"
+# and session processing. If this is enabled, PAM authentication will
+# be allowed through the ChallengeResponseAuthentication and
+# PasswordAuthentication.  Depending on your PAM configuration,
+# PAM authentication via ChallengeResponseAuthentication may bypass
+# the setting of "PermitRootLogin without-password".
+# If you just want the PAM account and session checks to run without
+# PAM authentication, then enable this but set PasswordAuthentication
+# and ChallengeResponseAuthentication to 'no'.
+# WARNING: 'UsePAM no' is not supported in Fedora and may cause several
+# problems.
+UsePAM yes
-SUBSYSTEM=="sound", GROUP="audio", \
+#AllowAgentForwarding yes
-  OPTIONS+="static_node=snd/seq", OPTIONS+="static_node=snd/timer"
+#AllowTcpForwarding yes
---More--
+#GatewayPorts no
-</code>
+X11Forwarding yes
+#X11DisplayOffset 10
+#X11UseLocalhost yes
+#PermitTTY yes
-Each rule has the following format:
+# It is recommended to use pam_motd in /etc/pam.d/sshd instead of PrintMotd,
+# as it is more configurable and versatile than the built-in version.
+PrintMotd no
-KEY, [KEY, ...] NAME [, SYMLINK]
+#PrintLastLog yes
+#TCPKeepAlive yes
+#PermitUserEnvironment no
+#Compression delayed
+#ClientAliveInterval 0
+#ClientAliveCountMax 3
+#UseDNS no
+#PidFile /var/run/sshd.pid
+#MaxStartups 10:30:100
+#PermitTunnel no
+#ChrootDirectory none
+#VersionAddendum none
-The Key is a **type=value** pair which uniquely identifies a peripheral. The **type** can be one of the following:
+# no default banner path
+#Banner none
-^ Type ^ Description ^ Examples ^
+# Accept locale-related environment variables
-| BUS | Bus type | usb, scsi, ide |
+AcceptEnv LANG LC_CTYPE LC_NUMERIC LC_TIME LC_COLLATE LC_MONETARY LC_MESSAGES
-| KERNEL | The default name given to the peripheral by the kernel | hda, ttyUSB0, lp0 |
+AcceptEnv LC_PAPER LC_NAME LC_ADDRESS LC_TELEPHONE LC_MEASUREMENT
-| SUBSYSTEM | The default sub-system name given by the Kernel, generally identical to the BUS value | usb, scsi |
+AcceptEnv LC_IDENTIFICATION LC_ALL LANGUAGE
-| DRIVER | The name of the module used by the peripheral | usb-storage |
+AcceptEnv XMODIFIERS
-| ID | The position of the peripheral on its bus | PCI bus id, USB id |
-| PLACE | The topological position of a USB oeripheral on its bus. | S/O |
-| SYSFS{filename} | The name of the peripheral file in /sys. This file contains the manufacturer's name, the label, the serial number and the UUID of the peripheral. Each rule can contains upto five references to files. | S/O |
-| PROGRAM | An eventual external program to be called in order to identify the peripheral | S/O |
-| RESULT | Value expected from PROGRAM | S/O |
-NAME and SYMLINK are used to tell udev what to do with the peripheral:
+# override default of no subsystems
+Subsystem       sftp    /usr/libexec/openssh/sftp-server
-^ Type ^ Description ^
+# Example of overriding settings on a per-user basis
-| NAME | The name of the peripheral in /dev |
+#Match User anoncvs
-| SYMLINK | The eventual symbolic links that point to NAME |
+#       X11Forwarding no
+#       AllowTcpForwarding no
-====The udevadm Command====
+#       PermitTTY no
+#       ForceCommand cvs server
-To obtain information from udev on a particular peripheral, you can use the **udevadm** command which has replaced the **udevinfo** command available in Red Hat/CentOS 5:
-<code>
-[root@centos8 ~]# udevadm info --query=all -n /dev/sda
-P: /devices/pci0000:00/0000:00:07.0/ata3/host2/target2:0:0/2:0:0:0/block/sda
-N: sda
-S: disk/by-id/ata-QEMU_HARDDISK_QM00005
-S: disk/by-id/scsi-0ATA_QEMU_HARDDISK_QM00005
-S: disk/by-id/scsi-1ATA_QEMU_HARDDISK_QM00005
-S: disk/by-id/scsi-SATA_QEMU_HARDDISK_QM00005
-S: disk/by-path/pci-0000:00:07.0-ata-1
-E: DEVLINKS=/dev/disk/by-path/pci-0000:00:07.0-ata-1 /dev/disk/by-id/scsi-SATA_QEMU_HARDDISK_QM00005 /dev/disk/by-id/ata-QEMU_HARDDISK_QM00005 /dev/disk/by-id/scsi-0ATA_QEMU_HARDDISK_QM00005 /dev/disk/by-id/scsi-1ATA_QEMU_HARDDISK_QM00005
-E: DEVNAME=/dev/sda
-E: DEVPATH=/devices/pci0000:00/0000:00:07.0/ata3/host2/target2:0:0/2:0:0:0/block/sda
-E: DEVTYPE=disk
-E: ID_ATA=1
-E: ID_ATA_FEATURE_SET_SMART=1
-E: ID_ATA_FEATURE_SET_SMART_ENABLED=1
-E: ID_ATA_SATA=1
-E: ID_ATA_WRITE_CACHE=1
-E: ID_ATA_WRITE_CACHE_ENABLED=1
-E: ID_BUS=ata
-E: ID_MODEL=QEMU_HARDDISK
-E: ID_MODEL_ENC=QEMU\x20HARDDISK\x20\x20\x20
-E: ID_PART_TABLE_TYPE=dos
-E: ID_PART_TABLE_UUID=b39ec5c8
-E: ID_PATH=pci-0000:00:07.0-ata-1
-E: ID_PATH_TAG=pci-0000_00_07_0-ata-1
-E: ID_REVISION=2.5+
-E: ID_SCSI=1
-E: ID_SCSI_INQUIRY=1
-E: ID_SERIAL=QEMU_HARDDISK_QM00005
-E: ID_SERIAL_SHORT=QM00005
-E: ID_TYPE=disk
-E: ID_VENDOR=ATA
-E: ID_VENDOR_ENC=ATA\x20\x20\x20\x20\x20
-E: MAJOR=8
-E: MINOR=0
-E: SCSI_IDENT_LUN_ATA=QEMU_HARDDISK_QM00005
-E: SCSI_IDENT_LUN_T10=ATA_QEMU_HARDDISK_QM00005
-E: SCSI_IDENT_LUN_VENDOR=QM00005
-E: SCSI_IDENT_SERIAL=QM00005
-E: SCSI_MODEL=QEMU_HARDDISK
-E: SCSI_MODEL_ENC=QEMU\x20HARDDISK\x20\x20\x20
-E: SCSI_REVISION=2.5+
-E: SCSI_TPGS=0
-E: SCSI_TYPE=disk
-E: SCSI_VENDOR=ATA
-E: SCSI_VENDOR_ENC=ATA\x20\x20\x20\x20\x20
-E: SUBSYSTEM=block
-E: TAGS=:systemd:
-E: USEC_INITIALIZED=8735808
 </code>
-The command line switches of this command are:
+To remove all empty and comment lines, use the following command:
 <code>
-[root@centos8 ~]# udevadm --help
+[root@centos8 ~]# cd /tmp ; grep -E -v '^(#|$)'  /etc/ssh/sshd_config > sshd_config
-udevadm [--help] [--version] [--debug] COMMAND [COMMAND OPTIONS]
+[root@centos8 tmp]# cat sshd_config
+HostKey /etc/ssh/ssh_host_rsa_key
-Send control commands or test the device manager.
+HostKey /etc/ssh/ssh_host_ecdsa_key
+HostKey /etc/ssh/ssh_host_ed25519_key
-Commands:
+SyslogFacility AUTHPRIV
-  info          Query sysfs or the udev database
+PermitRootLogin yes
-  trigger       Request events from the kernel
+AuthorizedKeysFile      .ssh/authorized_keys
-  settle        Wait for pending udev events
+PasswordAuthentication yes
-  control       Control the udev daemon
+ChallengeResponseAuthentication no
-  monitor       Listen to kernel and udev events
+GSSAPIAuthentication yes
-  test          Test an event run
+GSSAPICleanupCredentials no
-  test-builtin  Test a built-in command
+UsePAM yes
+X11Forwarding yes
-[root@centos8 ~]# udevadm info --help
+PrintMotd no
-udevadm info [OPTIONS] [DEVPATH|FILE]
+AcceptEnv LANG LC_CTYPE LC_NUMERIC LC_TIME LC_COLLATE LC_MONETARY LC_MESSAGES
+AcceptEnv LC_PAPER LC_NAME LC_ADDRESS LC_TELEPHONE LC_MEASUREMENT
-Query sysfs or the udev database.
+AcceptEnv LC_IDENTIFICATION LC_ALL LANGUAGE
+AcceptEnv XMODIFIERS
-  -h --help                   Print this message
+Subsystem       sftp    /usr/libexec/openssh/sftp-server
-  -V --version                Print version of the program
-  -q --query=TYPE             Query device information:
-       name                     Name of device node
-       symlink                  Pointing to node
-       path                     sysfs device path
-       property                 The device properties
-       all                      All values
-  -p --path=SYSPATH           sysfs device path used for query or attribute walk
-  -n --name=NAME              Node or symlink name used for query or attribute walk
-  -r --root                   Prepend dev directory to path names
-  -a --attribute-walk         Print all key matches walking along the chain
-                              of parent devices
-  -d --device-id-of-file=FILE Print major:minor of device containing this file
-  -x --export                 Export key/value pairs
-  -P --export-prefix          Export the key name with a prefix
-  -e --export-db              Export the content of the udev database
-  -c --cleanup-db             Clean up the udev database
 </code>
-=====The /sys Filesystem=====
+This file now has to be hardened by adding/editing the following directives:
-The virtual filesystem **/sys** was introduced with the 2.6 Kernel. Its role is to identify and describe peripherals for udev:
-<code>
-[root@centos8 ~]# ls -l /sys
-total 0
-drwxr-xr-x.   2 root root 0 Jul 12 08:15 block
-drwxr-xr-x.  33 root root 0 Jul 12 08:15 bus
-drwxr-xr-x.  57 root root 0 Jul 12 08:15 class
-drwxr-xr-x.   4 root root 0 Jul 12 08:15 dev
-drwxr-xr-x.  14 root root 0 Jul 12 08:15 devices
-drwxr-xr-x.   6 root root 0 Jul 12 08:15 firmware
-drwxr-xr-x.   9 root root 0 Jul 12 08:15 fs
-drwxr-xr-x.   2 root root 0 Jul 12 08:15 hypervisor
-drwxr-xr-x.  15 root root 0 Jul 12 08:15 kernel
-drwxr-xr-x. 153 root root 0 Jul 12 08:15 module
-drwxr-xr-x.   2 root root 0 Jul 12 08:15 power
-</code>
-Each directory contains specific information:
-  * **block**
-    * information concerning block devices
-  * **bus**
-    * information concerning buses
-  * **class**
-    * information concerning classes
-  * **devices**
-    * information concerning the posiion of devices on their bus
-  * **firmware**
-    * information concerning APCI
-  * **module**
-    * information concerning kernel modules
-  * **power**
-    * information concerning power management
-  * **fs**
-    * information concerning file systems
-For example:
-<code>
-[root@centos ~]# cat /sys/block/sda/sda1/size
-2097152
-</code>
-The figure returned is in sectors.
-=====LAB #4 - Limiting Ressources=====
-====4.1 - ulimit====
-Resources available to users can be limited by using the **ulimit** command.
-The **ulimit** command manages two limits:
-  * a //hard// hard limit by specifying the **-H** switch,
-  * a //soft// soft limit by specifying the **-S** switch.
-The soft limit is the limit imposed on the user whilst the hard limit is the limit that a user can obtain once he has gone over the soft limit.
-Only root can position a hard limit and only if the limit does not exceed real resource levels.
-Root can define limits by editing the **/etc/security/limits.conf** file:
-<code>
-[root@centos8 ~]# cat /etc/security/limits.conf
-# /etc/security/limits.conf
-#
-#This file sets the resource limits for the users logged in via PAM.
-#It does not affect resource limits of the system services.
-#
-#Also note that configuration files in /etc/security/limits.d directory,
-#which are read in alphabetical order, override the settings in this
-#file in case the domain is the same or more specific.
-#That means for example that setting a limit for wildcard domain here
-#can be overriden with a wildcard setting in a config file in the
-#subdirectory, but a user specific setting here can be overriden only
-#with a user specific setting in the subdirectory.
-#
-#Each line describes a limit for a user in the form:
-#
-#<domain>        <type>  <item>  <value>
-#
-#Where:
-#<domain> can be:
-#        - a user name
-#        - a group name, with @group syntax
-#        - the wildcard *, for default entry
-#        - the wildcard %, can be also used with %group syntax,
-#                 for maxlogin limit
-#
-#<type> can have the two values:
-#        - "soft" for enforcing the soft limits
-#        - "hard" for enforcing hard limits
-#
-#<item> can be one of the following:
-#        - core - limits the core file size (KB)
-#        - data - max data size (KB)
-#        - fsize - maximum filesize (KB)
-#        - memlock - max locked-in-memory address space (KB)
-#        - nofile - max number of open file descriptors
-#        - rss - max resident set size (KB)
-#        - stack - max stack size (KB)
-#        - cpu - max CPU time (MIN)
-#        - nproc - max number of processes
-#        - as - address space limit (KB)
-#        - maxlogins - max number of logins for this user
-#        - maxsyslogins - max number of logins on the system
-#        - priority - the priority to run user process with
-#        - locks - max number of file locks the user can hold
-#        - sigpending - max number of pending signals
-#        - msgqueue - max memory used by POSIX message queues (bytes)
-#        - nice - max nice priority allowed to raise to values: [-20, 19]
-#        - rtprio - max realtime priority
-#
-#<domain>      <type>  <item>         <value>
-#
-#*               soft    core            0
-#*               hard    rss             10000
-#@student        hard    nproc           20
-#@faculty        soft    nproc           20
-#@faculty        hard    nproc           50
-#ftp             hard    nproc           0
-#@student        -       maxlogins       4
-# End of file
-</code>
-<WRAP center round important 60%>
-**Important** : The limit can be a number or the word **unlimited**.
-</WRAP>
-For example if root adds the two following lines to /etc/security/limits.conf:
 <file>
-...
+AllowGroups adm
-trainee                soft        nofile          1024
+Banner /etc/issue.net
-trainee                hard        nofile          4096
+HostbasedAuthentication no
-...
+IgnoreRhosts yes
+LoginGraceTime 60
+LogLevel INFO
+PermitEmptyPasswords no
+PermitRootLogin no
+PrintLastLog yes
+Protocol 2
+StrictModes yes
+X11Forwarding no
 </file>
-the number of open files for trainee is limited to 1024. However trainee can increase this limit to 4 096 by using the following command:
+The file should look like this:
 <code>
-$ ulimit -n 4096
+[root@centos8 tmp]# vi sshd_config
+[root@centos8 tmp]# cat sshd_config
+AllowGroups adm
+Banner /etc/issue.net
+HostbasedAuthentication no
+IgnoreRhosts yes
+LoginGraceTime 60
+LogLevel INFO
+PermitEmptyPasswords no
+PermitRootLogin no
+PrintLastLog yes
+Protocol 2
+StrictModes yes
+X11Forwarding no
+HostKey /etc/ssh/ssh_host_rsa_key
+HostKey /etc/ssh/ssh_host_ecdsa_key
+HostKey /etc/ssh/ssh_host_ed25519_key
+SyslogFacility AUTHPRIV
+PermitRootLogin yes
+AuthorizedKeysFile      .ssh/authorized_keys
+PasswordAuthentication yes
+ChallengeResponseAuthentication no
+GSSAPIAuthentication yes
+GSSAPICleanupCredentials no
+UsePAM yes
+PrintMotd no
+AcceptEnv LANG LC_CTYPE LC_NUMERIC LC_TIME LC_COLLATE LC_MONETARY LC_MESSAGES
+AcceptEnv LC_PAPER LC_NAME LC_ADDRESS LC_TELEPHONE LC_MEASUREMENT
+AcceptEnv LC_IDENTIFICATION LC_ALL LANGUAGE
+AcceptEnv XMODIFIERS
+Subsystem       sftp    /usr/libexec/openssh/sftp-server
 </code>
-To see the list of the current limits use the **-a** switch:
+Rename the current **/etc/ssh/sshd_config** file as **/etc/ssh/sshd_config.old** :
 <code>
-[root@centos8 ~]# ulimit -a
+[root@centos8 tmp]# cp /etc/ssh/sshd_config /etc/ssh/sshd_config.old
-core file size          (blocks, -c) unlimited
-data seg size           (kbytes, -d) unlimited
-scheduling priority             (-e) 0
-file size               (blocks, -f) unlimited
-pending signals                 (-i) 14702
-max locked memory       (kbytes, -l) 64
-max memory size         (kbytes, -m) unlimited
-open files                      (-n) 1024
-pipe size            (512 bytes, -p) 8
-POSIX message queues     (bytes, -q) 819200
-real-time priority              (-r) 0
-stack size              (kbytes, -s) 8192
-cpu time               (seconds, -t) unlimited
-max user processes              (-u) 14702
-virtual memory          (kbytes, -v) unlimited
-file locks                      (-x) unlimited
 </code>
-The command line switches of this command are:
+Copy the **/tmp/sshd_config** file to **/etc/ssh/** :
 <code>
-[root@centos8 ~]# help ulimit
+[root@centos8 tmp]# cp /tmp/sshd_config /etc/ssh
-ulimit: ulimit [-SHabcdefiklmnpqrstuvxPT] [limit]
+cp: overwrite '/etc/ssh/sshd_config'? y
-    Modify shell resource limits.
-    Provides control over the resources available to the shell and processes
-    it creates, on systems that allow such control.
-    Options:
-      -S        use the `soft' resource limit
-      -H        use the `hard' resource limit
-      -a        all current limits are reported
-      -b        the socket buffer size
-      -c        the maximum size of core files created
-      -d        the maximum size of a process's data segment
-      -e        the maximum scheduling priority (`nice')
-      -f        the maximum size of files written by the shell and its children
-      -i        the maximum number of pending signals
-      -k        the maximum number of kqueues allocated for this process
-      -l        the maximum size a process may lock into memory
-      -m        the maximum resident set size
-      -n        the maximum number of open file descriptors
-      -p        the pipe buffer size
-      -q        the maximum number of bytes in POSIX message queues
-      -r        the maximum real-time scheduling priority
-      -s        the maximum stack size
-      -t        the maximum amount of cpu time in seconds
-      -u        the maximum number of user processes
-      -v        the size of virtual memory
-      -x        the maximum number of file locks
-      -P        the maximum number of pseudoterminals
-      -T        the maximum number of threads
-    Not all options are available on all platforms.
-    If LIMIT is given, it is the new value of the specified resource; the
-    special LIMIT values `soft', `hard', and `unlimited' stand for the
-    current soft limit, the current hard limit, and no limit, respectively.
-    Otherwise, the current value of the specified resource is printed.  If
-    no option is given, then -f is assumed.
-    Values are in 1024-byte increments, except for -t, which is in seconds,
-    -p, which is in increments of 512 bytes, and -u, which is an unscaled
-    number of processes.
-    Exit Status:
-    Returns success unless an invalid option is supplied or an error occurs.
 </code>
-====4.2 - CGroups====
+Restart the sshd service:
-Control Groups, also called **CGroups** are another, more modern way, of limiting resources.
-CGroups are organised hierarchially just like processes. However as opposed to processes, CGroups are organised into **multiples** hierarchies called **Resource Controllers** or simply **Controllers**.
-To consult the cgroup hierarchies, use the **lssubsys** command:
 <code>
-[root@centos8 ~]# lssubsys -am
+[root@centos8 tmp]# systemctl restart sshd
-bash: lssubsys: command not found...
+[root@centos8 tmp]# systemctl status sshd
-Install package 'libcgroup-tools' to provide command 'lssubsys'? [N/y] y
+● sshd.service - OpenSSH server daemon
+   Loaded: loaded (/usr/lib/systemd/system/sshd.service; enabled; vendor preset: enabled)
+   Active: active (running) since Mon 2021-08-30 02:17:00 EDT; 11s ago
+     Docs: man:sshd(8)
+           man:sshd_config(5)
+ Main PID: 1042039 (sshd)
+    Tasks: 1 (limit: 23535)
+   Memory: 1.1M
+   CGroup: /system.slice/sshd.service
+           └─1042039 /usr/sbin/sshd -D -oCiphers=aes256-gcm@openssh.com,chacha20-poly1305@openssh.com,aes256-ctr,aes256-cbc,aes128-gcm@openssh.com,a>
+Aug 30 02:17:00 centos8.ittraining.loc systemd[1]: Starting OpenSSH server daemon...
- * Waiting in queue...
+Aug 30 02:17:00 centos8.ittraining.loc sshd[1042039]: Server listening on 0.0.0.0 port 22.
-The following packages have to be installed:
+Aug 30 02:17:00 centos8.ittraining.loc sshd[1042039]: Server listening on :: port 22.
- libcgroup-0.41-19.el8.x86_64   Library to control and monitor control groups
+Aug 30 02:17:00 centos8.ittraining.loc systemd[1]: Started OpenSSH server daemon.
- libcgroup-tools-0.41-19.el8.x86_64     Command-line utility programs, services and daemons for libcgroup
+[q]
-Proceed with changes? [N/y] y
- * Waiting in queue...
- * Waiting for authentication...
- * Waiting in queue...
- * Downloading packages...
- * Requesting data...
- * Testing changes...
- * Installing packages...
-cpuset /sys/fs/cgroup/cpuset
-cpu,cpuacct /sys/fs/cgroup/cpu,cpuacct
-blkio /sys/fs/cgroup/blkio
-memory /sys/fs/cgroup/memory
-devices /sys/fs/cgroup/devices
-freezer /sys/fs/cgroup/freezer
-net_cls,net_prio /sys/fs/cgroup/net_cls,net_prio
-perf_event /sys/fs/cgroup/perf_event
-hugetlb /sys/fs/cgroup/hugetlb
-pids /sys/fs/cgroup/pids
-rdma /sys/fs/cgroup/rdma
 </code>
-<code>
+Put **trainee** in the **adm** group:
-[root@centos8 ~]# lssubsys -am
-cpuset /sys/fs/cgroup/cpuset
-cpu,cpuacct /sys/fs/cgroup/cpu,cpuacct
-blkio /sys/fs/cgroup/blkio
-memory /sys/fs/cgroup/memory
-devices /sys/fs/cgroup/devices
-freezer /sys/fs/cgroup/freezer
-net_cls,net_prio /sys/fs/cgroup/net_cls,net_prio
-perf_event /sys/fs/cgroup/perf_event
-hugetlb /sys/fs/cgroup/hugetlb
-pids /sys/fs/cgroup/pids
-rdma /sys/fs/cgroup/rdma
-</code>
-**Systemd** organises the processes in each cgroup. As a result, the CGroup resource management is closely aligned to Systemd's units.
-At the top of the hierarchy we can see the root slice -**-.slice**, under which we can find:
-  * **system.slice** - system services,
-  * **user.slice** - user sessions,
-  * **machine.slice** - virtiual machines and containers.
-Under these slices can be found:
-  * **scopes** -processes created by a **Fork**,
-  * **services** - processes created by a **Unit**.
-Slices can be consulted with the following command:
 <code>
-[root@centos8 ~]# systemctl list-units --type=slice
+[root@centos8 tmp]# groups trainee
-UNIT                                        LOAD   ACTIVE SUB    DESCRIPTION
+trainee : trainee
--.slice                                     loaded active active Root Slice
+[root@centos8 tmp]# usermod -aG adm trainee
-machine.slice                               loaded active active Virtual Machine and Container Slice
+[root@centos8 tmp]# groups trainee
-system-getty.slice                          loaded active active system-getty.slice
+trainee : trainee adm
-system-lvm2\x2dpvscan.slice                 loaded active active system-lvm2\x2dpvscan.slice
-system-sshd\x2dkeygen.slice                 loaded active active system-sshd\x2dkeygen.slice
-system-systemd\x2dfsck.slice                loaded active active system-systemd\x2dfsck.slice
-system-systemd\x2dhibernate\x2dresume.slice loaded active active system-systemd\x2dhibernate\x2dresume.slice
-system-user\x2druntime\x2ddir.slice         loaded active active system-user\x2druntime\x2ddir.slice
-system-vncserver.slice                      loaded active active system-vncserver.slice
-system.slice                                loaded active active System Slice
-user-1000.slice                             loaded active active User Slice of UID 1000
-user-42.slice                               loaded active active User Slice of UID 42
-user.slice                                  loaded active active User and Session Slice
-LOAD   = Reflects whether the unit definition was properly loaded.
-ACTIVE = The high-level unit activation state, i.e. generalization of SUB.
-SUB    = The low-level unit activation state, values depend on unit type.
-loaded units listed. Pass --all to see loaded but inactive units, too.
-To show all installed unit files use 'systemctl list-unit-files'.
 </code>
-CGroup hierarchies can be seen by using the **systemd-cgls** command:
+To generate the server keys, execute the following commands as **root**. Note that the passphrase must be **empty**:
 <code>
-[root@centos8 ~]# systemd-cgls
+[root@centos8 tmp]# ssh-keygen -t dsa
-Control group /:
+Generating public/private dsa key pair.
--.slice
+Enter file in which to save the key (/root/.ssh/id_dsa): /etc/ssh/ssh_host_dsa_key
-├─user.slice
+Enter passphrase (empty for no passphrase):
-│ ├─user-42.slice
+Enter same passphrase again:
-│ │ ├─session-c1.scope
+Your identification has been saved in /etc/ssh/ssh_host_dsa_key.
-│ │ │ ├─1317 gdm-session-worker [pam/gdm-launch-environment]
+Your public key has been saved in /etc/ssh/ssh_host_dsa_key.pub.
-│ │ │ ├─1459 /usr/libexec/gdm-wayland-session --register-session gnome-session --autostart /usr/share/gdm/greeter/autostart
+The key fingerprint is:
-│ │ │ ├─1856 /usr/libexec/gnome-session-binary --autostart /usr/share/gdm/greeter/autostart
+SHA256:dywC6jKyIMaTxsaEamz1kmthEmuG18HxmS22qRICOYk root@centos8.ittraining.loc
-│ │ │ ├─1882 /usr/bin/gnome-shell
+The key's randomart image is:
-│ │ │ ├─2059 /usr/bin/Xwayland :1024 -rootless -terminate -accessx -core -listen 4 -listen 5 -displayfd 6
++---[DSA 1024]----+
-│ │ │ ├─2132 ibus-daemon --xim --panel disable
+|                 |
-│ │ │ ├─2135 /usr/libexec/ibus-dconf
+|    .            |
-│ │ │ ├─2138 /usr/libexec/ibus-x11 --kill-daemon
+|.o . o.+         |
-│ │ │ ├─2251 /usr/libexec/gsd-xsettings
+|E.  o.*..  .     |
-│ │ │ ├─2261 /usr/libexec/gsd-a11y-settings
+|+ooo.o +S o o    |
-│ │ │ ├─2268 /usr/libexec/gsd-clipboard
+|X==++ o  o o     |
-│ │ │ ├─2271 /usr/libexec/gsd-color
+|B/=+oo           |
-│ │ │ ├─2272 /usr/libexec/gsd-datetime
+|Ooo++            |
-│ │ │ ├─2273 /usr/libexec/gsd-housekeeping
+|. .o             |
-│ │ │ ├─2274 /usr/libexec/gsd-keyboard
++----[SHA256]-----+
-│ │ │ ├─2275 /usr/libexec/gsd-media-keys
+</code>
-│ │ │ ├─2280 /usr/libexec/gsd-mouse
-│ │ │ ├─2281 /usr/libexec/gsd-power
-│ │ │ ├─2283 /usr/libexec/gsd-print-notifications
-│ │ │ ├─2284 /usr/libexec/gsd-rfkill
-│ │ │ ├─2285 /usr/libexec/gsd-screensaver-proxy
-│ │ │ ├─2290 /usr/libexec/gsd-sharing
-│ │ │ ├─2321 /usr/libexec/gsd-smartcard
-│ │ │ ├─2328 /usr/libexec/gsd-sound
-│ │ │ ├─2333 /usr/libexec/gsd-wacom
-│ │ │ └─2432 /usr/libexec/ibus-engine-simple
-│ │ └─user@42.service
-│ │   ├─xdg-permission-store.service
-│ │   │ └─2170 /usr/libexec/xdg-permission-store
-│ │   ├─pulseaudio.service
-│ │   │ └─1455 /usr/bin/pulseaudio --daemonize=no --log-target=journal
-│ │   ├─init.scope
-│ │   │ ├─1357 /usr/lib/systemd/systemd --user
-│ │   │ └─1377 (sd-pam)
-│ │   ├─at-spi-dbus-bus.service
-│ │   │ ├─2090 /usr/libexec/at-spi-bus-launcher
-│ │   │ ├─2095 /usr/bin/dbus-daemon --config-file=/usr/share/defaults/at-spi2/accessibility.conf --nofork --print-address 3
-│ │   │ └─2098 /usr/libexec/at-spi2-registryd --use-gnome-session
-│ │   └─dbus.service
-│ │     ├─1755 /usr/bin/dbus-daemon --session --address=systemd: --nofork --nopidfile --systemd-activation --syslog-only
-│ │     └─2143 /usr/libexec/ibus-portal
-│ └─user-1000.slice
-│   ├─user@1000.service
-│   │ ├─gvfs-goa-volume-monitor.service
-│   │ │ └─2369 /usr/libexec/gvfs-goa-volume-monitor
-│   │ ├─xdg-permission-store.service
-│   │ │ └─2191 /usr/libexec/xdg-permission-store
-│   │ ├─tracker-store.service
-│   │ │ └─2653 /usr/libexec/tracker-store
-│   │ ├─evolution-calendar-factory.service
-│   │ │ ├─2605 /usr/libexec/evolution-calendar-factory
-│   │ │ └─2706 /usr/libexec/evolution-calendar-factory-subprocess --factory all --bus-name org.gnome.evolution.dataserver.Subprocess.Backend.Calendarx2605x2 --own-path /org/gnome/evolution>
-│   │ ├─pulseaudio.service
-│   │ │ └─1456 /usr/bin/pulseaudio --daemonize=no --log-target=journal
-│   │ ├─gvfs-daemon.service
-│   │ │ ├─1896 /usr/libexec/gvfsd
-│   │ │ └─1901 /usr/libexec/gvfsd-fuse /run/user/1000/gvfs -f -o big_writes
-│   │ ├─evolution-source-registry.service
-│   │ │ └─2206 /usr/libexec/evolution-source-registry
-│   │ ├─gvfs-udisks2-volume-monitor.service
-│   │ │ └─2243 /usr/libexec/gvfs-udisks2-volume-monitor
-│   │ ├─init.scope
-│   │ │ ├─1239 /usr/lib/systemd/systemd --user
-│   │ │ └─1318 (sd-pam)
-│   │ ├─gvfs-gphoto2-volume-monitor.service
-│   │ │ └─2269 /usr/libexec/gvfs-gphoto2-volume-monitor
-│   │ ├─at-spi-dbus-bus.service
-│   │ │ ├─1964 /usr/libexec/at-spi-bus-launcher
-│   │ │ ├─1969 /usr/bin/dbus-daemon --config-file=/usr/share/defaults/at-spi2/accessibility.conf --nofork --print-address 3
-│   │ │ └─1972 /usr/libexec/at-spi2-registryd --use-gnome-session
-│   │ ├─dbus.service
-│   │ │ ├─1786 /usr/bin/dbus-daemon --session --address=systemd: --nofork --nopidfile --systemd-activation --syslog-only
-│   │ │ ├─2183 /usr/libexec/ibus-portal
-│   │ │ ├─2201 /usr/libexec/gnome-shell-calendar-server
-│   │ │ ├─2225 /usr/libexec/goa-daemon
-│   │ │ ├─2397 /usr/libexec/goa-identity-service
-│   │ │ └─2721 /usr/libexec/dconf-service
-│   │ ├─evolution-addressbook-factory.service
-│   │ │ ├─2727 /usr/libexec/evolution-addressbook-factory
-│   │ │ └─2771 /usr/libexec/evolution-addressbook-factory-subprocess --factory all --bus-name org.gnome.evolution.dataserver.Subprocess.Backend.AddressBookx2727x2 --own-path /org/gnome/evo>
-│   │ ├─gvfs-mtp-volume-monitor.service
-lines 44-86
-</code>
-Using Systemd, several resources can be limited:
-  * **CPUShares** - default value = 1024,
-  * **MemoryLimit** - expressed in MB or GB, there is no default value,
-  * **BlockIOWeight** - expressed as a value between 10 and 1000, there is no default value,
-  * **StartupCPUShares** - the same as CPUShares but only used during startup,
-  * **StartupBlockIOWeight** - the same as BlockIOWeight but only used during startup,
-  * **CPUQuota** - used to limit CPU usage even when the system is doing nothing.
-<WRAP center round important 60%>
-**Important** : You can check the systemd.resource-control(5) manual to see which CGroup parameters can be passed to systemctl.
-</WRAP>
-===Limiting Memory Usage===
-Start by creating the **hello-world.sh** script that will be used to work with CGroups :
 <code>
-[root@centos8 ~]# vi hello-world.sh
+[root@centos8 tmp]# ssh-keygen -t rsa
-[root@centos8 ~]# cat hello-world.sh
+Generating public/private rsa key pair.
-#!/bin/bash
+Enter file in which to save the key (/root/.ssh/id_rsa): /etc/ssh/ssh_host_rsa_key
-while [ 1 ]; do
+Enter passphrase (empty for no passphrase):
-        echo "hello world"
+Enter same passphrase again:
-        sleep 360
+Your identification has been saved in /etc/ssh/ssh_host_rsa_key.
-done
+Your public key has been saved in /etc/ssh/ssh_host_rsa_key.pub.
+The key fingerprint is:
+SHA256:8jXFK50NnoJCz9E7aPKpFYSYCstCPfRsdmlLBTNUnKg root@centos8.ittraining.loc
+The key's randomart image is:
++---[RSA 3072]----+
+|   .  .==o.      |
+|  o oo o=+ .     |
+|.. oo=+=o . +    |
+|oo .+E++.+ = *   |
+|o..   +.S B * .  |
+|.      B + =     |
+|        =        |
+|       o         |
+|      .          |
++----[SHA256]-----+
+[root@centos8 tmp]# ssh-keygen -t ecdsa
+Generating public/private ecdsa key pair.
+Enter file in which to save the key (/root/.ssh/id_ecdsa): /etc/ssh/ssh_host_ecdsa_key
+Enter passphrase (empty for no passphrase):
+Enter same passphrase again:
+Your identification has been saved in /etc/ssh/ssh_host_ecdsa_key.
+Your public key has been saved in /etc/ssh/ssh_host_ecdsa_key.pub.
+The key fingerprint is:
+SHA256:AMqFUJKGqnUEPh/IYda0wnbW1kXK+lnprpHsOo4UMbI root@centos8.ittraining.loc
+The key's randomart image is:
++---[ECDSA 256]---+
+|++*=+    .o      |
+|oX.=o+ o o       |
+|o %.B + +        |
+|...O.= o   .     |
+|..E.o . S o      |
+|.    . o =       |
+|    .   * .      |
+|   . ... o       |
+|    ..ooo..      |
++----[SHA256]-----+
+[root@centos8 tmp]# ssh-keygen -t ed25519
+Generating public/private ed25519 key pair.
+Enter file in which to save the key (/root/.ssh/id_ed25519): /etc/ssh/ssh_host_ed25519_key
+Enter passphrase (empty for no passphrase):
+Enter same passphrase again:
+Your identification has been saved in /etc/ssh/ssh_host_ed25519_key.
+Your public key has been saved in /etc/ssh/ssh_host_ed25519_key.pub.
+The key fingerprint is:
+SHA256:CtbcN9iXv00PfbHFGf2bEW7iRibOFwRctyqM5hmlhwE root@centos8.ittraining.loc
+The key's randomart image is:
++--[ED25519 256]--+
+|       E  .... . |
+|        .  .. . o|
+|         . . . +.|
+|     o . oB ..o.=|
+|    o o S*+=o* *+|
+|   . . .o.*o*.+.B|
+|      .  o o +o++|
+|            o  =o|
+|              . o|
++----[SHA256]-----+
 </code>
-Make the script runnable and test it:
+Public keys have a **.pub** extension:
 <code>
-[root@centos8 ~]# chmod u+x hello-world.sh
+[root@centos8 tmp]# ls /etc/ssh
-[root@centos8 ~]# ./hello-world.sh
+moduli      ssh_config.d  sshd_config.old     ssh_host_ecdsa_key.pub  ssh_host_ed25519_key.pub  ssh_host_rsa_key.pub
-hello world
+ssh_config  sshd_config   ssh_host_ecdsa_key  ssh_host_ed25519_key    ssh_host_rsa_key
-^C
 </code>
-Now create a CGroup in the **memory** sub-system called **helloworld** :
+Restart the sshd service:
 <code>
-[root@centos8 ~]# mkdir /sys/fs/cgroup/memory/helloworld
+[root@centos8 tmp]# systemctl restart sshd.service
-</code>
+[root@centos8 tmp]# systemctl status sshd.service
+● sshd.service - OpenSSH server daemon
+   Loaded: loaded (/usr/lib/systemd/system/sshd.service; enabled; vendor preset: enabled)
+   Active: active (running) since Mon 2021-08-30 02:24:57 EDT; 9s ago
+     Docs: man:sshd(8)
+           man:sshd_config(5)
+ Main PID: 1042204 (sshd)
+    Tasks: 1 (limit: 23535)
+   Memory: 1.1M
+   CGroup: /system.slice/sshd.service
+           └─1042204 /usr/sbin/sshd -D -oCiphers=aes256-gcm@openssh.com,chacha20-poly1305@openssh.com,aes256-ctr,aes256-cbc,aes128-gcm@openssh.com,a>
-By default, this CGroup inherits the use of the **all** of the available memory. To avoid that, create a **40,000,000** Byte limit for this CGroup:
+Aug 30 02:24:57 centos8.ittraining.loc systemd[1]: Starting OpenSSH server daemon...
+Aug 30 02:24:57 centos8.ittraining.loc sshd[1042204]: Server listening on 0.0.0.0 port 22.
-<code>
+Aug 30 02:24:57 centos8.ittraining.loc sshd[1042204]: Server listening on :: port 22.
-[root@centos8 ~]# echo 40000000 > /sys/fs/cgroup/memory/helloworld/memory.limit_in_bytes
+Aug 30 02:24:57 centos8.ittraining.loc systemd[1]: Started OpenSSH server daemon.
-[root@centos8 ~]# cat /sys/fs/cgroup/memory/helloworld/memory.limit_in_bytes
+[q]
-39997440
 </code>
-<WRAP center round important 60%>
+====3.3 - Configuring the Client====
-**Important** - Note that the 40,000,000 requested have become 39,997,440 which corresponds to a round number of Kernel Memory Pages, each of 4KB size ( 39,997,440 / 4,096 = 9,765 ).
-</WRAP>
-Now run the **helloworld.sh** script:
+To generate the client keys, execute the following commands as **trainee**. Note that the passphrase must be **empty**:
 <code>
-[root@centos8 ~]# ./hello-world.sh &
+[root@centos8 tmp]# exit
-[1] 35148
+logout
+[trainee@centos8 ~]$ ssh-keygen -t dsa
+Generating public/private dsa key pair.
+Enter file in which to save the key (/home/trainee/.ssh/id_dsa):
+Created directory '/home/trainee/.ssh'.
+Enter passphrase (empty for no passphrase):
+Enter same passphrase again:
+Your identification has been saved in /home/trainee/.ssh/id_dsa.
+Your public key has been saved in /home/trainee/.ssh/id_dsa.pub.
+The key fingerprint is:
+SHA256:Qd17X1iROjk5rLOQBbyVg1hNXkUdTeiFtEpn3rgPKc4 trainee@centos8.ittraining.loc
+The key's randomart image is:
++---[DSA 1024]----+
+|        =o+o.o+OB|
+|       o +o=o oo=|
+|        . +.+oB+ |
+|         o o.&+o.|
+|        S o o.*.o|
+|         o o   o.|
+|          . + +  |
+|           + . o |
+|            E   .|
++----[SHA256]-----+
+[trainee@centos8 ~]$ ssh-keygen -t rsa
+Generating public/private rsa key pair.
-[root@centos8 ~]# hello world
+Enter file in which to save the key (/home/trainee/.ssh/id_rsa): Enter passphrase (empty for no passphrase):
-[Enter] <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<PUSH Enter Key
+Enter same passphrase again:
+Your identification has been saved in /home/trainee/.ssh/id_rsa.
-[root@centos8 ~]# ps aux | grep hello-world
+Your public key has been saved in /home/trainee/.ssh/id_rsa.pub.
-root       35148  0.0  0.0  12724  2980 pts/1    S    08:48   0:00 /bin/bash ./hello-world.sh
+The key fingerprint is:
-root       35151  0.0  0.0  12136  1044 pts/1    S+   08:48   0:00 grep --color=auto hello-world
+SHA256:BgEjoWQrGCzdJfyZczVZYVoafiHsz9GK5PDWuywG/z0 trainee@centos8.ittraining.loc
+The key's randomart image is:
++---[RSA 3072]----+
+|o+o++oo  .oo*.   |
+|=+o.oo . .=B .   |
+|=.   ..o o+...   |
+|.     =.o o.. .  |
+|       oS= = o   |
+|       .. = =    |
+|         +   .   |
+|          +...E  |
+|         . o+... |
++----[SHA256]-----+
+[trainee@centos8 ~]$ ssh-keygen -t ecdsa
+Generating public/private ecdsa key pair.
+Enter file in which to save the key (/home/trainee/.ssh/id_ecdsa):
+Enter passphrase (empty for no passphrase):
+Enter same passphrase again:
+Your identification has been saved in /home/trainee/.ssh/id_ecdsa.
+Your public key has been saved in /home/trainee/.ssh/id_ecdsa.pub.
+The key fingerprint is:
+SHA256:mpBDgsCxP2DqRPkmGvXHpNnvm5B+Cl7MSiiZKfDjWLk trainee@centos8.ittraining.loc
+The key's randomart image is:
++---[ECDSA 256]---+
+|o..              |
+|.oo              |
+|.*o . .          |
+|+.++ B           |
+|+o =B + S        |
+|=*oo.* =         |
+|B.* o O .        |
+|.= = = o..       |
+|. E o oo+.       |
++----[SHA256]-----+
+[trainee@centos8 ~]$ ssh-keygen -t ed25519
+Generating public/private ed25519 key pair.
+Enter file in which to save the key (/home/trainee/.ssh/id_ed25519):
+Enter passphrase (empty for no passphrase):
+Enter same passphrase again:
+Your identification has been saved in /home/trainee/.ssh/id_ed25519.
+Your public key has been saved in /home/trainee/.ssh/id_ed25519.pub.
+The key fingerprint is:
+SHA256:JfFxG2mg9feAvFGxoxZ8uSsON3sXvtYQYYg5iVxzZS4 trainee@centos8.ittraining.loc
+The key's randomart image is:
++--[ED25519 256]--+
+|       ..o*=++=. |
+|        o==O+Boo |
+|        o ooE.O. |
+|         o   O.= |
+|        S   + ...|
+|           .  .o |
+|          . + o.o|
+|           + +.oo|
+|            o..o.|
++----[SHA256]-----+
 </code>
-Note that there is **no** memory limit:
+The keys can be found in the **~/.ssh/** directory:
 <code>
-[root@centos8 ~]# ps -ww -o cgroup 35148
+[trainee@centos8 ~]$ ls .ssh
-CGROUP
+id_dsa  id_dsa.pub  id_ecdsa  id_ecdsa.pub  id_ed25519  id_ed25519.pub  id_rsa  id_rsa.pub
-:memory:/user.slice/user-1000.slice/session-7.scope,7:devices:/user.slice,4:pids:/user.slice/user-1000.slice/session-7.scope,2:blkio:/user.slice,1:name=systemd:/user.slice/user-1000.slice/session-7.scope
 </code>
-NOw insert the PID of the script into the **helloworld** CGroup:
+====3.4 - Authentication using Asymetric Keys====
-<code>
+Connect to your own virtual machine as if it were the server:
-[root@centos8 ~]# echo 35148 > /sys/fs/cgroup/memory/helloworld/cgroup.procs
-</code>
-NOw you can see a memory limit - **12:memory:/helloworld**:
 <code>
-[root@centos8 ~]# ps -ww -o cgroup 35148
+[root@centos8 ~]# ssh -l trainee 127.0.0.1
-CGROUP
+\S
-:memory:/helloworld,7:devices:/user.slice,4:pids:/user.slice/user-1000.slice/session-7.scope,2:blkio:/user.slice,1:name=systemd:/user.slice/user-1000.slice/session-7.scope
+Kernel \r on an \m
-</code>
+trainee@127.0.0.1's password: trainee
+Activate the web console with: systemctl enable --now cockpit.socket
-Now check the actual memory consumption:
+[trainee@centos8 ~]$ ls -la | grep .ssh
+drwx------.  2 trainee trainee      4096 Aug 30 02:26 .ssh
-<code>
-[root@centos8 ~]# cat /sys/fs/cgroup/memory/helloworld/memory.usage_in_bytes
 </code>
-Kill the **hello-world.sh** script:
+Now transfer the client's **.ssh/id_ecdsa.pub** key to the server and rename it **authorized_keys** :
 <code>
-[root@centos8 ~]# kill 35148
+[trainee@centos8 ~]$ exit
-[root@centos8 ~]# ps aux | grep hello-world
+logout
-root       35307  0.0  0.0  12136  1112 pts/1    S+   08:55   0:00 grep --color=auto hello-world
+Connection to 127.0.0.1 closed.
-[1]+  Terminated              ./hello-world.sh
-</code>
-Create a more restrictive CGroup called **helloworld1** :
+[root@centos8 ~]# exit
+logout
-<code>
+[trainee@centos8 ~]$ scp .ssh/id_ecdsa.pub trainee@127.0.0.1:/home/trainee/.ssh/authorized_keys
-[root@centos8 ~]# mkdir /sys/fs/cgroup/memory/helloworld1
+The authenticity of host '127.0.0.1 (127.0.0.1)' can't be established.
-[root@centos8 ~]# echo 6000 > /sys/fs/cgroup/memory/helloworld1/memory.limit_in_bytes
+ECDSA key fingerprint is SHA256:Q7T/CP0SLiMbMAIgVzTuEHegYS/spPE5zzQchCHD5Vw.
-[root@centos8 ~]# cat /sys/fs/cgroup/memory/helloworld1/memory.limit_in_bytes
+Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
+Warning: Permanently added '127.0.0.1' (ECDSA) to the list of known hosts.
+\S
+Kernel \r on an \m
+trainee@127.0.0.1's password: trainee
+id_ecdsa.pub                                                                                                       100%  192   497.6KB/s   00:00
 </code>
-Re-run the script and put the PID in the new CGroup:
+Re-connect to your own virtual machine as if it were the server:
 <code>
-[root@centos8 ~]# ./hello-world.sh &
+[trainee@centos8 ~]$ ssh -l trainee localhost
-[1] 35389
+The authenticity of host 'localhost (::1)' can't be established.
+ECDSA key fingerprint is SHA256:Q7T/CP0SLiMbMAIgVzTuEHegYS/spPE5zzQchCHD5Vw.
+Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
+Warning: Permanently added 'localhost' (ECDSA) to the list of known hosts.
+\S
+Kernel \r on an \m
+Activate the web console with: systemctl enable --now cockpit.socket
-[root@centos8 ~]# hello world
+Last login: Mon Aug 30 03:57:14 2021 from 127.0.0.1
-[Enter]
+[trainee@centos8 ~]$
-[root@centos8 ~]# echo 35389 > /sys/fs/cgroup/memory/helloworld1/cgroup.procs
-</code>
-Wait for **hello world** to appear. You will notice that the script has stopped:
-<code>
-[root@centos8 ~]# hello world
-[Enter] <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<PUSH Enter Key
-[1]+  Killed                  ./hello-world.sh
-</code>
-===The cgcreate Command===
-This command creates a CGroup:
-<code>
-[root@centos8 ~]# cgcreate -g memory:helloworld2
-[root@centos8 ~]# ls -l /sys/fs/cgroup/memory/helloworld2/
-total 0
--rw-rw-r--. 1 root root 0 Jul 13 10:39 cgroup.clone_children
---w--w----. 1 root root 0 Jul 13 10:39 cgroup.event_control
--rw-rw-r--. 1 root root 0 Jul 13 10:39 cgroup.procs
--rw-rw-r--. 1 root root 0 Jul 13 10:39 memory.failcnt
---w--w----. 1 root root 0 Jul 13 10:39 memory.force_empty
--rw-rw-r--. 1 root root 0 Jul 13 10:39 memory.kmem.failcnt
--rw-rw-r--. 1 root root 0 Jul 13 10:39 memory.kmem.limit_in_bytes
--rw-rw-r--. 1 root root 0 Jul 13 10:39 memory.kmem.max_usage_in_bytes
--r--r--r--. 1 root root 0 Jul 13 10:39 memory.kmem.slabinfo
--rw-rw-r--. 1 root root 0 Jul 13 10:39 memory.kmem.tcp.failcnt
--rw-rw-r--. 1 root root 0 Jul 13 10:39 memory.kmem.tcp.limit_in_bytes
--rw-rw-r--. 1 root root 0 Jul 13 10:39 memory.kmem.tcp.max_usage_in_bytes
--r--r--r--. 1 root root 0 Jul 13 10:39 memory.kmem.tcp.usage_in_bytes
--r--r--r--. 1 root root 0 Jul 13 10:39 memory.kmem.usage_in_bytes
--rw-rw-r--. 1 root root 0 Jul 13 10:39 memory.limit_in_bytes
--rw-rw-r--. 1 root root 0 Jul 13 10:39 memory.max_usage_in_bytes
--rw-rw-r--. 1 root root 0 Jul 13 10:39 memory.memsw.failcnt
--rw-rw-r--. 1 root root 0 Jul 13 10:39 memory.memsw.limit_in_bytes
--rw-rw-r--. 1 root root 0 Jul 13 10:39 memory.memsw.max_usage_in_bytes
--r--r--r--. 1 root root 0 Jul 13 10:39 memory.memsw.usage_in_bytes
--rw-rw-r--. 1 root root 0 Jul 13 10:39 memory.move_charge_at_immigrate
--r--r--r--. 1 root root 0 Jul 13 10:39 memory.numa_stat
--rw-rw-r--. 1 root root 0 Jul 13 10:39 memory.oom_control
-----------. 1 root root 0 Jul 13 10:39 memory.pressure_level
--rw-rw-r--. 1 root root 0 Jul 13 10:39 memory.soft_limit_in_bytes
--r--r--r--. 1 root root 0 Jul 13 10:39 memory.stat
--rw-rw-r--. 1 root root 0 Jul 13 10:39 memory.swappiness
--r--r--r--. 1 root root 0 Jul 13 10:39 memory.usage_in_bytes
--rw-rw-r--. 1 root root 0 Jul 13 10:39 memory.use_hierarchy
--rw-rw-r--. 1 root root 0 Jul 13 10:39 notify_on_release
--rw-rw-r--. 1 root root 0 Jul 13 10:39 tasks
-</code>
-Set a memory limit for **helloworld2**:
-<code>
-[root@centos8 ~]# echo 40000000 > /sys/fs/cgroup/memory/helloworld2/memory.limit_in_bytes
-</code>
-==The cgexec Command==
-This command inserts the limit into the CGroup **and** launches the script:
-<code>
-[root@centos8 ~]# cgexec -g memory:helloworld2 ./hello-world.sh &
-[1] 37670
-[root@centos8 ~]# hello world
-[Enter]
-[root@centos8 ~]#
-</code>
-==THe cgdelete Command==
-Once the sxcript has terminated, this command deletes the CGroup:
-<code>
-[root@centos8 ~]# ps aux | grep *.sh
-root       37670  0.0  0.0  12724  3112 pts/1    S    10:41   0:00 /bin/bash ./hello-world.sh
-root       37685  0.0  0.0  12136  1148 pts/1    S+   10:42   0:00 grep --color=auto hello-world.sh
-[root@centos8 ~]# kill 37670
-root@centos8 ~]# ps aux | grep *.sh
-root       37726  0.0  0.0  12136  1156 pts/1    R+   10:43   0:00 grep --color=auto hello-world.sh
-[1]+  Terminated              cgexec -g memory:helloworld2 ./hello-world.sh
-[root@centos8 ~]# cgdelete memory:helloworld2
-[root@centos8 ~]# ls -l /sys/fs/cgroup/memory/helloworld2/
-ls: cannot access '/sys/fs/cgroup/memory/helloworld2/': No such file or directory
-</code>
-==The /etc/cgconfig.conf File==
-In order for limites to be persistent, it is necessary to edit the **/etc/cgconfig.conf** file:
-<code>
-[root@centos8 ~]# vi /etc/cgconfig.conf
-[root@centos8 ~]# cat /etc/cgconfig.conf
-#
-#  Copyright IBM Corporation. 2007
-#
-#  Authors:     Balbir Singh <balbir@linux.vnet.ibm.com>
-#  This program is free software; you can redistribute it and/or modify it
-#  under the terms of version 2.1 of the GNU Lesser General Public License
-#  as published by the Free Software Foundation.
-#
-#  This program is distributed in the hope that it would be useful, but
-#  WITHOUT ANY WARRANTY; without even the implied warranty of
-#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
-#
-#
-# By default, we expect systemd mounts everything on boot,
-# so there is not much to do.
-# See man cgconfig.conf for further details, how to create groups
-# on system boot using this file.
-group helloworld2 {
-        cpu {
-                cpu.shares = 100;
-        }
-        memory {
-                memory.limit_in_bytes = 40000;
-        }
-}
 </code>
 <WRAP center round important 60%>
-**Important** - Here you have created **two** limits : a memory limit of 40,000 Bytes and a **cpu.shares** limoit of **100**. This latter corresponds to about 9,77% of the CPU.
+**Important** - Note that no password is required.
 </WRAP>
-Now create the **two** CGroups:
-<code>
-[root@centos8 ~]# cgcreate -g memory:helloworld2
-[root@centos8 ~]# ls -l /sys/fs/cgroup/memory/helloworld2/
-total 0
--rw-rw-r--. 1 root root 0 Jul 13 10:46 cgroup.clone_children
---w--w----. 1 root root 0 Jul 13 10:46 cgroup.event_control
--rw-rw-r--. 1 root root 0 Jul 13 10:46 cgroup.procs
--rw-rw-r--. 1 root root 0 Jul 13 10:46 memory.failcnt
---w--w----. 1 root root 0 Jul 13 10:46 memory.force_empty
--rw-rw-r--. 1 root root 0 Jul 13 10:46 memory.kmem.failcnt
--rw-rw-r--. 1 root root 0 Jul 13 10:46 memory.kmem.limit_in_bytes
--rw-rw-r--. 1 root root 0 Jul 13 10:46 memory.kmem.max_usage_in_bytes
--r--r--r--. 1 root root 0 Jul 13 10:46 memory.kmem.slabinfo
--rw-rw-r--. 1 root root 0 Jul 13 10:46 memory.kmem.tcp.failcnt
--rw-rw-r--. 1 root root 0 Jul 13 10:46 memory.kmem.tcp.limit_in_bytes
--rw-rw-r--. 1 root root 0 Jul 13 10:46 memory.kmem.tcp.max_usage_in_bytes
--r--r--r--. 1 root root 0 Jul 13 10:46 memory.kmem.tcp.usage_in_bytes
--r--r--r--. 1 root root 0 Jul 13 10:46 memory.kmem.usage_in_bytes
--rw-rw-r--. 1 root root 0 Jul 13 10:46 memory.limit_in_bytes
--rw-rw-r--. 1 root root 0 Jul 13 10:46 memory.max_usage_in_bytes
--rw-rw-r--. 1 root root 0 Jul 13 10:46 memory.memsw.failcnt
--rw-rw-r--. 1 root root 0 Jul 13 10:46 memory.memsw.limit_in_bytes
--rw-rw-r--. 1 root root 0 Jul 13 10:46 memory.memsw.max_usage_in_bytes
--r--r--r--. 1 root root 0 Jul 13 10:46 memory.memsw.usage_in_bytes
--rw-rw-r--. 1 root root 0 Jul 13 10:46 memory.move_charge_at_immigrate
--r--r--r--. 1 root root 0 Jul 13 10:46 memory.numa_stat
--rw-rw-r--. 1 root root 0 Jul 13 10:46 memory.oom_control
-----------. 1 root root 0 Jul 13 10:46 memory.pressure_level
--rw-rw-r--. 1 root root 0 Jul 13 10:46 memory.soft_limit_in_bytes
--r--r--r--. 1 root root 0 Jul 13 10:46 memory.stat
--rw-rw-r--. 1 root root 0 Jul 13 10:46 memory.swappiness
--r--r--r--. 1 root root 0 Jul 13 10:46 memory.usage_in_bytes
--rw-rw-r--. 1 root root 0 Jul 13 10:46 memory.use_hierarchy
--rw-rw-r--. 1 root root 0 Jul 13 10:46 notify_on_release
--rw-rw-r--. 1 root root 0 Jul 13 10:46 tasks
-</code>
-<code>
-[root@centos8 ~]# cgcreate -g cpu:helloworld2
-[root@centos8 ~]# ls -l /sys/fs/cgroup/cpu/helloworld2/
-total 0
--rw-rw-r--. 1 root root 0 Jul 13 10:47 cgroup.clone_children
--rw-rw-r--. 1 root root 0 Jul 13 10:47 cgroup.procs
--r--r--r--. 1 root root 0 Jul 13 10:47 cpuacct.stat
--rw-rw-r--. 1 root root 0 Jul 13 10:47 cpuacct.usage
--r--r--r--. 1 root root 0 Jul 13 10:47 cpuacct.usage_all
--r--r--r--. 1 root root 0 Jul 13 10:47 cpuacct.usage_percpu
--r--r--r--. 1 root root 0 Jul 13 10:47 cpuacct.usage_percpu_sys
--r--r--r--. 1 root root 0 Jul 13 10:47 cpuacct.usage_percpu_user
--r--r--r--. 1 root root 0 Jul 13 10:47 cpuacct.usage_sys
--r--r--r--. 1 root root 0 Jul 13 10:47 cpuacct.usage_user
--rw-rw-r--. 1 root root 0 Jul 13 10:47 cpu.cfs_period_us
--rw-rw-r--. 1 root root 0 Jul 13 10:47 cpu.cfs_quota_us
--rw-rw-r--. 1 root root 0 Jul 13 10:47 cpu.rt_period_us
--rw-rw-r--. 1 root root 0 Jul 13 10:47 cpu.rt_runtime_us
--rw-rw-r--. 1 root root 0 Jul 13 10:47 cpu.shares
--r--r--r--. 1 root root 0 Jul 13 10:47 cpu.stat
--rw-rw-r--. 1 root root 0 Jul 13 10:47 notify_on_release
--rw-rw-r--. 1 root root 0 Jul 13 10:47 tasks
-</code>
-==The cgconfigparser Command==
-Apply the contents of the **/etc/cgconfig.conf** file using the **cgconfigparser** command:
-<code>
-[root@centos8 ~]# cgconfigparser -l /etc/cgconfig.conf
-[root@centos8 ~]# cat /sys/fs/cgroup/memory/helloworld2/memory.limit_in_bytes
-[root@centos8 ~]# cat /sys/fs/cgroup/cpu/helloworld2/cpu.shares
-</code>
 -----
-Copyright © 2021 Hugh Norris.
+Copyright © 2022 Hugh Norris

Piste : • LCE513 - Managing the Network

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