Ceci est une ancienne révision du document !
Table des matières
Version : 2023.01
Dernière mise-à-jour : 2023/12/08 14:52
LCF604 - Gestion du Réseau
Contenu du Module
- LCF604 - Gestion du Réseau
- Contenu du Module
- Présentation
- La Commande nmcli
- LAB #1 - Configuration du Réseau
- 1.1 - Connections et Profils
- 1.2 - Résolution des Noms
- 1.3 - Ajouter une Deuxième Adresse IP à un Profil
- 1.4 - La Commande hostname
- 1.5 - La Commande ip
- 1.6 - Activer/Désactiver une Interface Manuellement
- 1.7 - Routage Statique
- La commande ip
- Activer/désactiver le routage sur le serveur
- LAB #2 - Diagnostique du Réseau
- 2.1 - ping
- 2.2 - netstat -i
- 2.3 - traceroute
- LAB #3 - Connexions à Distance
- 3.1 - Telnet
- 3.2 - wget
- 3.3 - ftp
- 3.4 - SSH
- Présentation
- SSH-1
- SSH-2
- Authentification par mot de passe
- Authentification par clef asymétrique
- Configuration du Serveur
- Configuration du Client
- Tunnels SSH
- 3.5 - SCP
- Présentation
- Utilisation
- 3.6 - Mise en Place des Clefs Asymétriques
Présentation
RHEL/CentOS 8 utilise Network Manager pour gérer le réseau. Network Manager est composé de deux éléments :
- un service qui gère les connexions réseaux et rapporte leurs états,
- des front-ends qui passent par un API de configuration du service.
Important : Notez qu'avec cette version de NetworkManager, IPv6 est activée par défaut.
Le service NetworkManager doit toujours être lancé :
[root@centos8 ~]# systemctl status NetworkManager.service
● NetworkManager.service - Network Manager
Loaded: loaded (/usr/lib/systemd/system/NetworkManager.service; enabled; vendor pr>
Active: active (running) since Thu 2021-07-22 05:05:29 EDT; 1 months 7 days ago
Docs: man:NetworkManager(8)
Main PID: 1002 (NetworkManager)
Tasks: 3 (limit: 23535)
Memory: 6.8M
CGroup: /system.slice/NetworkManager.service
└─1002 /usr/sbin/NetworkManager --no-daemon
Warning: Journal has been rotated since unit was started. Log output is incomplete or>
lines 1-11/11 (END)
[^q]
La Commande nmcli
La commande nmcli (Network Manager Command Line Interface) est utilisée pour configurer NetworkManager.
Les options et les sous-commandes peuvent être consultées en utilisant les commandes suivantes :
[root@centos8 ~]# nmcli help
Usage: nmcli [OPTIONS] OBJECT { COMMAND | help }
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
OBJECT
g[eneral] NetworkManager's general status and operations
n[etworking] overall networking control
r[adio] NetworkManager radio switches
c[onnection] NetworkManager's connections
d[evice] devices managed by NetworkManager
a[gent] NetworkManager secret agent or polkit agent
m[onitor] monitor NetworkManager changes
LAB #1 - Configuration du Réseau
1.1 - Connections et Profils
NetworkManager inclus la notion de connections ou profils permettant des configurations différentes en fonction de la localisation. Pour voir les connections actuelles, utilisez la commande nmcli c avec la sous-commande show :
[root@centos8 ~]# nmcli c show NAME UUID TYPE DEVICE ens18 fc4a4d23-b15e-47a7-bcfa-b2e08f49553e ethernet ens18 virbr0 03f6c432-2a09-47e7-9693-208431a572ee bridge virbr0
Créez donc un profil IP fixe rattaché au périphérique ens18 :
[root@centos8 ~]# nmcli connection add con-name ip_fixe ifname ens18 type ethernet ip4 10.0.2.46/24 gw4 10.0.2.1 Connection 'ip_fixe' (0f48c74d-5d16-4c37-8220-24644507b589) successfully added.
Constatez sa présence :
[root@centos8 ~]# nmcli c show NAME UUID TYPE DEVICE ens18 fc4a4d23-b15e-47a7-bcfa-b2e08f49553e ethernet ens18 virbr0 03f6c432-2a09-47e7-9693-208431a572ee bridge virbr0 ip_fixe 0f48c74d-5d16-4c37-8220-24644507b589 ethernet --
Notez que la sortie n'indique pas que le profil ip_fixe soit associé au periphérique ens18 car le profil ip_fixe n'est pas activé :
[root@centos8 ~]# nmcli d show GENERAL.DEVICE: ens18 GENERAL.TYPE: ethernet GENERAL.HWADDR: 4E:B1:31:BD:5D:B2 GENERAL.MTU: 1500 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 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: -- 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 GENERAL.DEVICE: virbr0-nic GENERAL.TYPE: tun GENERAL.HWADDR: 52:54:00:79:02:66 GENERAL.MTU: 1500 GENERAL.STATE: 10 (unmanaged) GENERAL.CONNECTION: -- GENERAL.CON-PATH: -- lines 28-50/50 (END) [q]
Pour activer le profil ip_fixe, utilisez la commande suivante :
[root@centos8 ~]# nmcli connection up ip_fixe
Notez que votre terminal est bloqué à cause du changement de l'adresse IP.
A faire - Revenez à l'accueil du cloud IT Training et re-connectez-vous à la VM en tant que trainee en utilisant la connexion CentOS8_SSH_10.0.2.46.
Le profil ip_fixe est maintenant activé tandis que le profil enp0s3 a été désactivé :
[root@centos8 ~]# nmcli c show NAME UUID TYPE DEVICE ip_fixe 0f48c74d-5d16-4c37-8220-24644507b589 ethernet ens18 virbr0 03f6c432-2a09-47e7-9693-208431a572ee bridge virbr0 ens18 fc4a4d23-b15e-47a7-bcfa-b2e08f49553e ethernet -- [root@centos8 ~]# nmcli d show GENERAL.DEVICE: ens18 GENERAL.TYPE: ethernet GENERAL.HWADDR: 4E:B1:31:BD:5D:B2 GENERAL.MTU: 1500 GENERAL.STATE: 100 (connected) GENERAL.CONNECTION: ip_fixe 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 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: -- 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 GENERAL.DEVICE: virbr0-nic GENERAL.TYPE: tun GENERAL.HWADDR: 52:54:00:79:02:66 GENERAL.MTU: 1500 GENERAL.STATE: 10 (unmanaged) GENERAL.CONNECTION: -- GENERAL.CON-PATH: -- lines 27-49/49 (END) [q]
Pour consulter les paramètres du profil ens18, utilisez la commande suivante :
[root@centos8 ~]# nmcli -p connection show ens18
===============================================================================
Connection profile details (ens18)
===============================================================================
connection.id: ens18
connection.uuid: fc4a4d23-b15e-47a7-bcfa-b2e08f49553e
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: 1630224060
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
-------------------------------------------------------------------------------
802-3-ethernet.port: --
802-3-ethernet.speed: 0
802-3-ethernet.duplex: --
802-3-ethernet.auto-negotiate: no
802-3-ethernet.mac-address: --
802-3-ethernet.cloned-mac-address: --
802-3-ethernet.generate-mac-address-mask:--
802-3-ethernet.mac-address-blacklist: --
802-3-ethernet.mtu: auto
802-3-ethernet.s390-subchannels: --
802-3-ethernet.s390-nettype: --
802-3-ethernet.s390-options: --
802-3-ethernet.wake-on-lan: default
802-3-ethernet.wake-on-lan-password: --
-------------------------------------------------------------------------------
ipv4.method: manual
ipv4.dns: 8.8.8.8
ipv4.dns-search: ittraining.loc
ipv4.dns-options: --
ipv4.dns-priority: 0
ipv4.addresses: 10.0.2.45/24
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: 0 (disabled)
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: --
-------------------------------------------------------------------------------
lines 56-100/100 (END)
[q]
De même, pour consulter les paramètres du profil ip_fixe, utilisez la commande suivante :
[root@centos8 ~]# nmcli -p connection show ip_fixe
===============================================================================
Connection profile details (ip_fixe)
===============================================================================
connection.id: ip_fixe
connection.uuid: 0f48c74d-5d16-4c37-8220-24644507b589
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: 1630224329
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
-------------------------------------------------------------------------------
802-3-ethernet.port: --
802-3-ethernet.speed: 0
802-3-ethernet.duplex: --
802-3-ethernet.auto-negotiate: no
802-3-ethernet.mac-address: --
802-3-ethernet.cloned-mac-address: --
802-3-ethernet.generate-mac-address-mask:--
802-3-ethernet.mac-address-blacklist: --
802-3-ethernet.mtu: auto
802-3-ethernet.s390-subchannels: --
802-3-ethernet.s390-nettype: --
802-3-ethernet.s390-options: --
802-3-ethernet.wake-on-lan: default
802-3-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_fixe
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]
Pour consulter la liste profils associés à un périphérique, utilisez la commande suivante :
[root@centos8 ~]# nmcli -f CONNECTIONS device show ens18 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_fixe
Les fichiers de configuration pour le periphérique ens18 se trouvent dans le répertoire /etc/sysconfig/network-scripts/ :
[root@centos8 ~]# ls -l /etc/sysconfig/network-scripts/ | grep ifcfg -rw-r--r--. 1 root root 417 Jun 16 06:39 ifcfg-ens18 -rw-r--r--. 1 root root 326 Aug 29 03:58 ifcfg-ip_fixe
1.2 - Résolution des Noms
L'étude du fichier /etc/sysconfig/network-scripts/ifcfg-ip_fixe démontre l'abscence de directives concernant les DNS :
[root@centos8 ~]# cat /etc/sysconfig/network-scripts/ifcfg-ip_fixe TYPE=Ethernet PROXY_METHOD=none BROWSER_ONLY=no BOOTPROTO=none IPADDR=10.0.2.46 PREFIX=24 GATEWAY=10.0.2.1 DEFROUTE=yes IPV4_FAILURE_FATAL=no IPV6INIT=yes IPV6_AUTOCONF=yes IPV6_DEFROUTE=yes IPV6_FAILURE_FATAL=no IPV6_ADDR_GEN_MODE=stable-privacy NAME=ip_fixe UUID=0f48c74d-5d16-4c37-8220-24644507b589 DEVICE=ens18 ONBOOT=yes
La résolution des noms est donc inactive :
[root@centos8 ~]# ping www.free.fr ping: www.free.fr: Name or service not known
Modifiez donc la configuration du profil ip_fixe :
[root@centos8 ~]# nmcli connection mod ip_fixe ipv4.dns 8.8.8.8
L'étude du fichier /etc/sysconfig/network-scripts/ifcfg-ip_fixe démontre que la directive concernant le serveur DNS a été ajoutée :
[root@centos8 ~]# cat /etc/sysconfig/network-scripts/ifcfg-ip_fixe TYPE=Ethernet PROXY_METHOD=none BROWSER_ONLY=no BOOTPROTO=none IPADDR=10.0.2.46 PREFIX=24 GATEWAY=10.0.2.1 DEFROUTE=yes IPV4_FAILURE_FATAL=no IPV6INIT=yes IPV6_AUTOCONF=yes IPV6_DEFROUTE=yes IPV6_FAILURE_FATAL=no IPV6_ADDR_GEN_MODE=stable-privacy NAME=ip_fixe UUID=0f48c74d-5d16-4c37-8220-24644507b589 DEVICE=ens18 ONBOOT=yes DNS1=8.8.8.8
Afin que la modification du serveur DNS soit prise en compte, re-démarrez le service NetworkManager :
root@centos8 ~]# systemctl restart NetworkManager.service
[root@centos8 ~]# systemctl status NetworkManager.service
● NetworkManager.service - Network Manager
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
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>
Aug 29 04:15:12 centos8.ittraining.loc NetworkManager[973390]: <info> [1630224912.2241] manager: NetworkManager state is now CONNECTED_LOCAL
Aug 29 04:15:12 centos8.ittraining.loc NetworkManager[973390]: <info> [1630224912.2251] policy: set 'ip_fixe' (ens18) as default for IPv4 routing a>
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]
Vérifiez que le fichier /etc/resolv.conf ait été modifié par NetworkManager :
[root@centos8 ~]# cat /etc/resolv.conf # Generated by NetworkManager search ittraining.loc nameserver 8.8.8.8
Dernièrement vérifiez la resolution des noms :
[root@centos8 ~]# ping www.free.fr PING www.free.fr (212.27.48.10) 56(84) bytes of data. 64 bytes from www.free.fr (212.27.48.10): icmp_seq=1 ttl=47 time=29.3 ms 64 bytes from www.free.fr (212.27.48.10): icmp_seq=2 ttl=47 time=29.4 ms 64 bytes from www.free.fr (212.27.48.10): icmp_seq=3 ttl=47 time=29.4 ms 64 bytes from www.free.fr (212.27.48.10): icmp_seq=4 ttl=47 time=29.4 ms ^C --- www.free.fr ping statistics --- 4 packets transmitted, 4 received, 0% packet loss, time 3005ms rtt min/avg/max/mdev = 29.266/29.377/29.428/0.183 ms
Important : Notez qu'il existe un front-end graphique en mode texte, nmtui, pour configurer NetworkManager.
1.3 - Ajouter une Deuxième Adresse IP à un Profil
Pour ajouter une deuxième adresse IP à un profil sous RHEL/CentOS 8, il convient d'utiliser la commande suivante :
[root@centos8 ~]# nmcli connection mod ip_fixe +ipv4.addresses 192.168.1.2/24
Rechargez la configuration du profil :
[root@centos8 ~]# nmcli con up ip_fixe
Saisissez ensuite la commande suivante :
[root@centos8 ~]# nmcli connection show ip_fixe connection.id: ip_fixe connection.uuid: 0f48c74d-5d16-4c37-8220-24644507b589 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: -1 802-3-ethernet.port: -- 802-3-ethernet.speed: 0 802-3-ethernet.duplex: -- 802-3-ethernet.auto-negotiate: no 802-3-ethernet.mac-address: -- 802-3-ethernet.cloned-mac-address: -- 802-3-ethernet.generate-mac-address-mask:-- 802-3-ethernet.mac-address-blacklist: -- 802-3-ethernet.mtu: auto 802-3-ethernet.s390-subchannels: -- 802-3-ethernet.s390-nettype: -- 802-3-ethernet.s390-options: -- 802-3-ethernet.wake-on-lan: default 802-3-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_fixe 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]
Important : Notez l'ajout de l'adresse secondaire à la ligne ipv4.addresses: ainsi que l'ajout de la ligne IP4.ADDRESS[2]:.
Consultez maintenant le contenu du fichier /etc/sysconfig/network-scripts/ifcfg-ip_fixe :
[root@centos8 ~]# cat /etc/sysconfig/network-scripts/ifcfg-ip_fixe TYPE=Ethernet PROXY_METHOD=none BROWSER_ONLY=no BOOTPROTO=none IPADDR=10.0.2.46 PREFIX=24 GATEWAY=10.0.2.1 DEFROUTE=yes IPV4_FAILURE_FATAL=no IPV6INIT=yes IPV6_AUTOCONF=yes IPV6_DEFROUTE=yes IPV6_FAILURE_FATAL=no IPV6_ADDR_GEN_MODE=stable-privacy NAME=ip_fixe UUID=0f48c74d-5d16-4c37-8220-24644507b589 DEVICE=ens18 ONBOOT=yes DNS1=8.8.8.8 IPADDR1=192.168.1.2 PREFIX1=24
Important : Notez l'ajout de la ligne IPADDR1=192.168.1.2.
1.4 - La Commande hostname
La procédure de la modification du hostname est simplifiée et sa prise en compte est immédiate :
[root@centos8 ~]# hostname centos8.ittraining.loc [root@centos8 ~]# nmcli general hostname centos.ittraining.loc [root@centos8 ~]# cat /etc/hostname centos.ittraining.loc [root@centos8 ~]# hostname centos.ittraining.loc [root@centos8 ~]# nmcli general hostname centos8.ittraining.loc [root@centos8 ~]# cat /etc/hostname centos8.ittraining.loc [root@centos8 ~]# hostname centos8.ittraining.loc
1.5 - La Commande ip
Sous RHEL/CentOS 8 la commande ip est préférée par rapport à la commande ifconfig :
[root@centos8 ~]# ip address
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
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
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: ens18: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
link/ether 4e:b1:31:bd:5d:b2 brd ff:ff:ff:ff:ff:ff
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
valid_lft forever preferred_lft forever
inet6 fe80::5223:aee1:998e:9f27/64 scope link noprefixroute
valid_lft forever preferred_lft forever
3: virbr0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default qlen 1000
link/ether 52:54:00:79:02:66 brd ff:ff:ff:ff:ff:ff
inet 192.168.122.1/24 brd 192.168.122.255 scope global virbr0
valid_lft forever preferred_lft forever
4: 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
Options de la Commande ip
Les options de cette commande sont :
[root@centos8 ~]# ip --help
Usage: ip [ OPTIONS ] OBJECT { COMMAND | help }
ip [ -force ] -batch filename
where OBJECT := { link | address | addrlabel | route | rule | neigh | ntable |
tunnel | tuntap | maddress | mroute | mrule | monitor | xfrm |
netns | l2tp | fou | macsec | tcp_metrics | token | netconf | ila |
vrf | sr | nexthop | mptcp }
OPTIONS := { -V[ersion] | -s[tatistics] | -d[etails] | -r[esolve] |
-h[uman-readable] | -iec | -j[son] | -p[retty] |
-f[amily] { inet | inet6 | mpls | bridge | link } |
-4 | -6 | -I | -D | -M | -B | -0 |
-l[oops] { maximum-addr-flush-attempts } | -br[ief] |
-o[neline] | -t[imestamp] | -ts[hort] | -b[atch] [filename] |
-rc[vbuf] [size] | -n[etns] name | -N[umeric] | -a[ll] |
-c[olor]}
1.6 - Activer/Désactiver une Interface Manuellement
Deux commandes existent pour désactiver et activer manuellement une interface réseau :
# nmcli device disconnect enp0s3 # nmcli device connect enp0s3
Important : Veuillez ne PAS exécuter ces deux commandes.
1.7 - Routage Statique
La commande ip
Sous RHEL/CentOS 8, pour supprimer la route vers le réseau 192.168.1.0 il convient d'utiliser la commande ip et non pas la commande route :
[root@centos8 ~]# ip route default via 10.0.2.1 dev ens18 proto static metric 100 10.0.2.0/24 dev ens18 proto kernel scope link src 10.0.2.46 metric 100 192.168.1.0/24 dev ens18 proto kernel scope link src 192.168.1.2 metric 100 192.168.122.0/24 dev virbr0 proto kernel scope link src 192.168.122.1 linkdown root@centos8 ~]# ip route del 192.168.1.0/24 via 0.0.0.0 [root@centos8 ~]# ip route default via 10.0.2.1 dev ens18 proto static metric 100 10.0.2.0/24 dev ens18 proto kernel scope link src 10.0.2.46 metric 100 192.168.122.0/24 dev virbr0 proto kernel scope link src 192.168.122.1 linkdown
Pour ajouter la route vers le réseau 192.168.1.0 :
[root@centos8 ~]# ip route add 192.168.1.0/24 via 10.0.2.1 [root@centos8 ~]# ip route default via 10.0.2.1 dev ens18 proto static metric 100 10.0.2.0/24 dev ens18 proto kernel scope link src 10.0.2.46 metric 100 192.168.1.0/24 via 10.0.2.1 dev ens18 192.168.122.0/24 dev virbr0 proto kernel scope link src 192.168.122.1 linkdown
Important - La commande utilisée pour ajouter une passerelle par défaut prend la forme suivante ip route add default via adresse ip.
Désactiver/Activer le routage sur le serveur
Pour désactiver le routage sur le serveur, il convient de désactiver la retransmission des paquets.
Pour IPv4 :
[root@centos8 ~]# cat /proc/sys/net/ipv4/ip_forward 1 [root@centos8 ~]# echo 0 > /proc/sys/net/ipv4/ip_forward [root@centos8 ~]# cat /proc/sys/net/ipv4/ip_forward 0
Pour activer le routage sur le serveur, il convient d'activer la retransmission des paquets:
[root@centos8 ~]# echo 1 > /proc/sys/net/ipv4/ip_forward [root@centos8 ~]# cat /proc/sys/net/ipv4/ip_forward 1
Pour IPv6 :
[root@centos8 ~]# cat /proc/sys/net/ipv6/conf/all/forwarding 1 [root@centos8 ~]# echo "0" > /proc/sys/net/ipv6/conf/all/forwarding [root@centos8 ~]# cat /proc/sys/net/ipv6/conf/all/forwarding 0
Pour activer le routage sur le serveur, il convient d'activer la retransmission des paquets:
[root@centos8 ~]# echo "1" > /proc/sys/net/ipv6/conf/all/forwarding [root@centos8 ~]# cat /proc/sys/net/ipv6/conf/all/forwarding 1
LAB #2 - Diagnostique du Réseau
2.1 - ping
Pour tester l'accessibilité d'une machine, vous devez utiliser la commande ping :
[root@centos8 ~]# ping -c4 10.0.2.1 PING 10.0.2.1 (10.0.2.1) 56(84) bytes of data. 64 bytes from 10.0.2.1: icmp_seq=1 ttl=64 time=0.104 ms 64 bytes from 10.0.2.1: icmp_seq=2 ttl=64 time=0.325 ms 64 bytes from 10.0.2.1: icmp_seq=3 ttl=64 time=0.250 ms 64 bytes from 10.0.2.1: icmp_seq=4 ttl=64 time=0.123 ms --- 10.0.2.1 ping statistics --- 4 packets transmitted, 4 received, 0% packet loss, time 3083ms rtt min/avg/max/mdev = 0.104/0.200/0.325/0.092 ms
Options de la commande ping
Les options de cette commande sont :
[root@centos8 ~]# ping --help
ping: invalid option -- '-'
Usage: ping [-aAbBdDfhLnOqrRUvV64] [-c count] [-i interval] [-I interface]
[-m mark] [-M pmtudisc_option] [-l preload] [-p pattern] [-Q tos]
[-s packetsize] [-S sndbuf] [-t ttl] [-T timestamp_option]
[-w deadline] [-W timeout] [hop1 ...] destination
Usage: ping -6 [-aAbBdDfhLnOqrRUvV] [-c count] [-i interval] [-I interface]
[-l preload] [-m mark] [-M pmtudisc_option]
[-N nodeinfo_option] [-p pattern] [-Q tclass] [-s packetsize]
[-S sndbuf] [-t ttl] [-T timestamp_option] [-w deadline]
[-W timeout] destination
2.2 - netstat -i
Pour visualiser les statistiques réseaux, vous disposez de la commande netstat :
[root@centos8 ~]# netstat -i Kernel Interface table Iface MTU RX-OK RX-ERR RX-DRP RX-OVR TX-OK TX-ERR TX-DRP TX-OVR Flg ens18 1500 476056 0 0 0 363562 0 0 0 BMRU lo 65536 10936 0 0 0 10936 0 0 0 LRU virbr0 1500 0 0 0 0 0 0 0 0 BMU
Options de la commande netstat
Les options de cette commande sont :
[root@centos8 ~]# netstat --help
usage: netstat [-vWeenNcCF] [<Af>] -r netstat {-V|--version|-h|--help}
netstat [-vWnNcaeol] [<Socket> ...]
netstat { [-vWeenNac] -I[<Iface>] | [-veenNac] -i | [-cnNe] -M | -s [-6tuw] } [delay]
-r, --route display routing table
-I, --interfaces=<Iface> display interface table for <Iface>
-i, --interfaces display interface table
-g, --groups display multicast group memberships
-s, --statistics display networking statistics (like SNMP)
-M, --masquerade display masqueraded connections
-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
-l, --listening display listening server sockets
-a, --all display all sockets (default: connected)
-F, --fib display Forwarding Information Base (default)
-C, --cache display routing cache instead of FIB
-Z, --context display SELinux security context for sockets
<Socket>={-t|--tcp} {-u|--udp} {-U|--udplite} {-S|--sctp} {-w|--raw}
{-x|--unix} --ax25 --ipx --netrom
<AF>=Use '-6|-4' or '-A <af>' or '--<af>'; default: inet
List of possible address families (which support routing):
inet (DARPA Internet) inet6 (IPv6) ax25 (AMPR AX.25)
netrom (AMPR NET/ROM) ipx (Novell IPX) ddp (Appletalk DDP)
x25 (CCITT X.25)
2.3 - traceroute
La commande ping est à la base de la commande traceroute. Cette commande sert à découvrir la route empruntée pour accéder à un site donné :
[root@centos8 ~]# traceroute www.ittraining.network bash: traceroute: command not found... Install package 'traceroute' to provide command 'traceroute'? [N/y] y * 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 * Waiting in queue... * Waiting for authentication... * Waiting in queue... * Downloading packages... * Requesting data... * Testing changes... * Installing packages... traceroute to www.ittraining.network (109.228.56.52), 30 hops max, 60 byte packets 1 _gateway (10.0.2.1) 0.132 ms 0.101 ms 0.078 ms 2 79.137.68.252 (79.137.68.252) 0.542 ms 0.656 ms 0.809 ms 3 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 4 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 5 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 6 waw-wa2-sbb1-nc5.pl.eu (91.121.131.150) 1.102 ms 1.396 ms 1.099 ms 7 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 8 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 9 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 10 ae-14.bb-b.fr7.fra.de.oneandone.net (212.227.120.149) 22.222 ms 22.206 ms 22.257 ms 11 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 12 109.228.63.209 (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 13 * 109.228.63.209 (109.228.63.209) 38.014 ms 37.991 ms 14 * * * 15 * * * 16 * * * 17 * * * 18 * * * 19 * * * 20 * * * 21 * * * 22 * * * 23 * * * 24 * * * 25 * * * 26 * * * 27 * * * 28 * * * 29 * * *^C
Options de la commande traceroute
Les options de cette commande sont :
[root@centos8 ~]# traceroute --help
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
3
-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
Arguments:
+ host The host to traceroute to
packetlen The full packet length (default is the length of an IP
header plus 40). Can be ignored or increased to a minimal
allowed value
LAB #3 - Connexions à Distance
3.1 - Telnet
Important - Si la commande telnet n'est pas installée sous CentOS 8, installez-le à l'aide de la commande dnf install telnet en tant que root.
La commande telnet est utilisée pour établir une connexion à distance avec un serveur telnet :
# telnet numero_ip
Important - Le service telnet revient à une redirection des canaux standards d'entrée et de sortie. Notez que la connexion n'est pas sécurisée. Pour fermer la connexion, il faut saisir la commande exit. La commande telnet n'offre pas de services de transfert de fichiers. Pour cela, il convient d'utiliser la command ftp.
Options de la commande telnet
Les options de cette commande sont :
[[root@centos8 ~]# telnet --help
telnet: invalid option -- '-'
Usage: telnet [-4] [-6] [-8] [-E] [-L] [-S tos] [-a] [-c] [-d] [-e char] [-l user]
[-n tracefile] [-b hostalias ] [-r]
[host-name [port]]
3.2 - wget
La commande wget est utilisée pour récupérer un fichier via http, https ou ftp :
[root@centos8 ~]# wget https://www.dropbox.com/s/wk79lkfr6f12u9j/wget_file.txt ... [root@centos8 ~]# cat wget_file.txt This is a file retrieved by the wget command.
Options de la commande wget
Les options de cette commande sont :
[root@centos8 ~]# wget --help
GNU Wget 1.19.5, a non-interactive network retriever.
Usage: wget [OPTION]... [URL]...
Mandatory arguments to long options are mandatory for short options too.
Startup:
-V, --version display the version of Wget and exit
-h, --help print this help
-b, --background go to background after startup
-e, --execute=COMMAND execute a `.wgetrc'-style command
Logging and input file:
-o, --output-file=FILE log messages to FILE
-a, --append-output=FILE append messages to FILE
-d, --debug print lots of debugging information
-q, --quiet quiet (no output)
-v, --verbose be verbose (this is the default)
-nv, --no-verbose turn off verboseness, without being quiet
--report-speed=TYPE output bandwidth as TYPE. TYPE can be bits
-i, --input-file=FILE download URLs found in local or external FILE
--input-metalink=FILE download files covered in local Metalink FILE
-F, --force-html treat input file as HTML
-B, --base=URL resolves HTML input-file links (-i -F)
relative to URL
--config=FILE specify config file to use
--no-config do not read any config file
--rejected-log=FILE log reasons for URL rejection to FILE
Download:
-t, --tries=NUMBER set number of retries to NUMBER (0 unlimits)
--retry-connrefused retry even if connection is refused
--retry-on-http-error=ERRORS comma-separated list of HTTP errors to retry
-O, --output-document=FILE write documents to FILE
-nc, --no-clobber skip downloads that would download to
existing files (overwriting them)
--no-netrc don't try to obtain credentials from .netrc
-c, --continue resume getting a partially-downloaded file
--start-pos=OFFSET start downloading from zero-based position OFFSET
--progress=TYPE select progress gauge type
--show-progress display the progress bar in any verbosity mode
-N, --timestamping don't re-retrieve files unless newer than
local
--no-if-modified-since don't use conditional if-modified-since get
requests in timestamping mode
--no-use-server-timestamps don't set the local file's timestamp by
the one on the server
-S, --server-response print server response
--spider don't download anything
-T, --timeout=SECONDS set all timeout values to SECONDS
--dns-timeout=SECS set the DNS lookup timeout to SECS
--connect-timeout=SECS set the connect timeout to SECS
--read-timeout=SECS set the read timeout to SECS
-w, --wait=SECONDS wait SECONDS between retrievals
--waitretry=SECONDS wait 1..SECONDS between retries of a retrieval
--random-wait wait from 0.5*WAIT...1.5*WAIT secs between retrievals
--no-proxy explicitly turn off proxy
-Q, --quota=NUMBER set retrieval quota to NUMBER
--bind-address=ADDRESS bind to ADDRESS (hostname or IP) on local host
--limit-rate=RATE limit download rate to RATE
--no-dns-cache disable caching DNS lookups
--restrict-file-names=OS restrict chars in file names to ones OS allows
--ignore-case ignore case when matching files/directories
-4, --inet4-only connect only to IPv4 addresses
-6, --inet6-only connect only to IPv6 addresses
--prefer-family=FAMILY connect first to addresses of specified family,
one of IPv6, IPv4, or none
--user=USER set both ftp and http user to USER
--password=PASS set both ftp and http password to PASS
--ask-password prompt for passwords
--use-askpass=COMMAND specify credential handler for requesting
username and password. If no COMMAND is
specified the WGET_ASKPASS or the SSH_ASKPASS
environment variable is used.
--no-iri turn off IRI support
--local-encoding=ENC use ENC as the local encoding for IRIs
--remote-encoding=ENC use ENC as the default remote encoding
--unlink remove file before clobber
--keep-badhash keep files with checksum mismatch (append .badhash)
--metalink-index=NUMBER Metalink application/metalink4+xml metaurl ordinal NUMBER
--metalink-over-http use Metalink metadata from HTTP response headers
--preferred-location preferred location for Metalink resources
--xattr turn on storage of metadata in extended file attributes
Directories:
-nd, --no-directories don't create directories
-x, --force-directories force creation of directories
-nH, --no-host-directories don't create host directories
--protocol-directories use protocol name in directories
-P, --directory-prefix=PREFIX save files to PREFIX/..
--cut-dirs=NUMBER ignore NUMBER remote directory components
HTTP options:
--http-user=USER set http user to USER
--http-password=PASS set http password to PASS
--no-cache disallow server-cached data
--default-page=NAME change the default page name (normally
this is 'index.html'.)
-E, --adjust-extension save HTML/CSS documents with proper extensions
--ignore-length ignore 'Content-Length' header field
--header=STRING insert STRING among the headers
--compression=TYPE choose compression, one of auto, gzip and none. (default: none)
--max-redirect maximum redirections allowed per page
--proxy-user=USER set USER as proxy username
--proxy-password=PASS set PASS as proxy password
--referer=URL include 'Referer: URL' header in HTTP request
--save-headers save the HTTP headers to file
-U, --user-agent=AGENT identify as AGENT instead of Wget/VERSION
--no-http-keep-alive disable HTTP keep-alive (persistent connections)
--no-cookies don't use cookies
--load-cookies=FILE load cookies from FILE before session
--save-cookies=FILE save cookies to FILE after session
--keep-session-cookies load and save session (non-permanent) cookies
--post-data=STRING use the POST method; send STRING as the data
--post-file=FILE use the POST method; send contents of FILE
--method=HTTPMethod use method "HTTPMethod" in the request
--body-data=STRING send STRING as data. --method MUST be set
--body-file=FILE send contents of FILE. --method MUST be set
--content-disposition honor the Content-Disposition header when
choosing local file names (EXPERIMENTAL)
--content-on-error output the received content on server errors
--auth-no-challenge send Basic HTTP authentication information
without first waiting for the server's
challenge
HTTPS (SSL/TLS) options:
--secure-protocol=PR choose secure protocol, one of auto, SSLv2,
SSLv3, TLSv1, TLSv1_1, TLSv1_2 and PFS
--https-only only follow secure HTTPS links
--no-check-certificate don't validate the server's certificate
--certificate=FILE client certificate file
--certificate-type=TYPE client certificate type, PEM or DER
--private-key=FILE private key file
--private-key-type=TYPE private key type, PEM or DER
--ca-certificate=FILE file with the bundle of CAs
--ca-directory=DIR directory where hash list of CAs is stored
--crl-file=FILE file with bundle of CRLs
--pinnedpubkey=FILE/HASHES Public key (PEM/DER) file, or any number
of base64 encoded sha256 hashes preceded by
'sha256//' and separated by ';', to verify
peer against
--ciphers=STR Set the priority string (GnuTLS) or cipher list string (OpenSSL) directly.
Use with care. This option overrides --secure-protocol.
The format and syntax of this string depend on the specific SSL/TLS engine.
HSTS options:
--no-hsts disable HSTS
--hsts-file path of HSTS database (will override default)
FTP options:
--ftp-user=USER set ftp user to USER
--ftp-password=PASS set ftp password to PASS
--no-remove-listing don't remove '.listing' files
--no-glob turn off FTP file name globbing
--no-passive-ftp disable the "passive" transfer mode
--preserve-permissions preserve remote file permissions
--retr-symlinks when recursing, get linked-to files (not dir)
FTPS options:
--ftps-implicit use implicit FTPS (default port is 990)
--ftps-resume-ssl resume the SSL/TLS session started in the control connection when
opening a data connection
--ftps-clear-data-connection cipher the control channel only; all the data will be in plaintext
--ftps-fallback-to-ftp fall back to FTP if FTPS is not supported in the target server
WARC options:
--warc-file=FILENAME save request/response data to a .warc.gz file
--warc-header=STRING insert STRING into the warcinfo record
--warc-max-size=NUMBER set maximum size of WARC files to NUMBER
--warc-cdx write CDX index files
--warc-dedup=FILENAME do not store records listed in this CDX file
--no-warc-compression do not compress WARC files with GZIP
--no-warc-digests do not calculate SHA1 digests
--no-warc-keep-log do not store the log file in a WARC record
--warc-tempdir=DIRECTORY location for temporary files created by the
WARC writer
Recursive download:
-r, --recursive specify recursive download
-l, --level=NUMBER maximum recursion depth (inf or 0 for infinite)
--delete-after delete files locally after downloading them
-k, --convert-links make links in downloaded HTML or CSS point to
local files
--convert-file-only convert the file part of the URLs only (usually known as the basename)
--backups=N before writing file X, rotate up to N backup files
-K, --backup-converted before converting file X, back up as X.orig
-m, --mirror shortcut for -N -r -l inf --no-remove-listing
-p, --page-requisites get all images, etc. needed to display HTML page
--strict-comments turn on strict (SGML) handling of HTML comments
Recursive accept/reject:
-A, --accept=LIST comma-separated list of accepted extensions
-R, --reject=LIST comma-separated list of rejected extensions
--accept-regex=REGEX regex matching accepted URLs
--reject-regex=REGEX regex matching rejected URLs
--regex-type=TYPE regex type (posix)
-D, --domains=LIST comma-separated list of accepted domains
--exclude-domains=LIST comma-separated list of rejected domains
--follow-ftp follow FTP links from HTML documents
--follow-tags=LIST comma-separated list of followed HTML tags
--ignore-tags=LIST comma-separated list of ignored HTML tags
-H, --span-hosts go to foreign hosts when recursive
-L, --relative follow relative links only
-I, --include-directories=LIST list of allowed directories
--trust-server-names use the name specified by the redirection
URL's last component
-X, --exclude-directories=LIST list of excluded directories
-np, --no-parent don't ascend to the parent directory
Email bug reports, questions, discussions to <bug-wget@gnu.org>
and/or open issues at https://savannah.gnu.org/bugs/?func=additem&group=wget.
3.3 - ftp
Important - Si la commande ftp n'est pas installée sous CentOS 8, installez-le à l'aide de la commande dnf install ftp en tant que root.
La commande ftp est utilisée pour le transfert de fichiers. Une fois connecté, il convient d'utiliser la commande help pour afficher la liste des commandes disponibles :
ftp> help Commands may be abbreviated. Commands are: ! debug mdir sendport site $ dir mget put size account disconnect mkdir pwd status append exit mls quit struct ascii form mode quote system bell get modtime recv sunique binary glob mput reget tenex bye hash newer rstatus tick case help nmap rhelp trace cd idle nlist rename type cdup image ntrans reset user chmod lcd open restart umask close ls prompt rmdir verbose cr macdef passive runique ? delete mdelete proxy send ftp>
Le caractère ! permet d'exécuter une commande sur la machine cliente
ftp> !pwd /root
Pour transférer un fichier vers le serveur, il convient d'utiliser la commande put :
ftp> put nom_fichier_local nom_fichier_distant
Vous pouvez également transférer plusieurs fichiers à la fois grâce à la commande mput. Dans ce cas précis, il convient de saisir la commande suivante:
ftp> mput nom*.*
Pour transférer un fichier du serveur, il convient d'utiliser la commande get :
ftp> get nom_fichier
Vous pouvez également transférer plusieurs fichiers à la fois grâce à la commande mget ( voir la commande mput ci-dessus ).
Pour supprimer un fichier sur le serveur, il convient d'utiliser la commande del :
ftp> del nom_fichier
Pour fermer la session, il convient d'utiliser la commande quit :
ftp> quit [root@centos7 ~]#
3.4 - SSH
Présentation
La commande ssh est le successeur et la remplaçante de la commande rlogin. Il permet d'établir des connexions sécurisées avec une machine distante. SSH comporte cinq acteurs :
- Le serveur SSH
- le démon sshd, qui s'occupe des authentifications et autorisations des clients,
- Le client SSH
- ssh ou scp, qui assure la connexion et le dialogue avec le serveur,
- La session qui représente la connexion courante et qui commence juste après l'authentification réussie,
- Les clefs
- Couple de clef utilisateur asymétriques et persistantes qui assurent l'identité d'un utilisateur et qui sont stockés sur disque dur,
- Clef hôte asymétrique et persistante garantissant l'identité du serveur er qui est conservé sur disque dur
- Clef serveur asymétrique et temporaire utilisée par le protocole SSH1 qui sert au chiffrement de la clé de session,
- Clef de session symétrique qui est générée aléatoirement et qui permet le chiiffrement de la communication entre le client et le serveur. Elle est détruite en fin de session. SSH-1 utilise une seule clef tandis que SSH-2 utilise une clef par direction de la communication,
- La base de données des hôtes connus qui stocke les clés des connexions précédentes.
SSH fonctionne de la manière suivante pour la la mise en place d'un canal sécurisé:
- Le client contacte le serveur sur son port 22,
- Les client et le serveur échangent leur version de SSH. En cas de non-compatibilité de versions, l'un des deux met fin au processus,
- Le serveur SSH s'identifie auprès du client en lui fournissant :
- Sa clé hôte,
- Sa clé serveur,
- Une séquence aléatoire de huit octets à inclure dans les futures réponses du client,
- Une liste de méthodes de chiffrage, compression et authentification,
- Le client et le serveur produisent un identifiant identique, un haché MD5 long de 128 bits contenant la clé hôte, la clé serveur et la séquence aléatoire,
- Le client génère sa clé de session symétrique et la chiffre deux fois de suite, une fois avec la clé hôte du serveur et la deuxième fois avec la clé serveur. Le client envoie cette clé au serveur accompagnée de la séquence aléatoire et un choix d'algorithmes supportés,
- Le serveur déchiffre la clé de session,
- Le client et le serveur mettent en place le canal sécurisé.
SSH-1
SSH-1 utilise une paire de clefs de type RSA1. Il assure l'intégrité des données par une Contrôle de Redondance Cyclique (CRC) et est un bloc dit monolithique.
Afin de s'identifier, le client essaie chacune des six méthodes suivantes :
- Kerberos,
- Rhosts,
- RhostsRSA,
- Par clef asymétrique,
- TIS,
- Par mot de passe.
SSH-2
SSH-2 utilise DSA ou RSA. Il assure l'intégrité des données par l'algorithme HMAC. SSH-2 est organisé en trois couches :
- SSH-TRANS – Transport Layer Protocol,
- SSH-AUTH – Authentification Protocol,
- SSH-CONN – Connection Protocol.
SSH-2 diffère de SSH-1 essentiellement dans la phase authentification.
Trois méthodes d'authentification :
- Par clef asymétrique,
- Identique à SSH-1 sauf avec l'algorithme DSA,
- RhostsRSA,
- Par mot de passe.
Options de la commande
Les options de cette commande sont :
[root@centos8 ~]# ssh --help
unknown option -- -
usage: ssh [-46AaCfGgKkMNnqsTtVvXxYy] [-B bind_interface]
[-b bind_address] [-c cipher_spec] [-D [bind_address:]port]
[-E log_file] [-e escape_char] [-F configfile] [-I pkcs11]
[-i identity_file] [-J [user@]host[:port]] [-L address]
[-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port]
[-Q query_option] [-R address] [-S ctl_path] [-W host:port]
[-w local_tun[:remote_tun]] destination [command]
Authentification par mot de passe
L'utilisateur fournit un mot de passe au client ssh. Le client ssh le transmet de façon sécurisée au serveur ssh puis le serveur vérifie le mot de passe et l'accepte ou non.
Avantage:
- Aucune configuration de clef asymétrique n'est nécessaire.
Inconvénients:
- L'utilisateur doit fournir à chaque connexion un identifiant et un mot de passe,
- Moins sécurisé qu'un système par clef asymétrique.
Authentification par clef asymétrique
- Le client envoie au serveur une requête d'authentification par clé asymétrique qui contient le module de la clé à utiliser,
- Le serveur recherche une correspondance pour ce module dans le fichier des clés autorisés ~/.ssh/authorized_keys,
- Dans le cas où une correspondance n'est pas trouvée, le serveur met fin à la communication,
- Dans le cas contraire le serveur génère une chaîne aléatoire de 256 bits appelée un challenge et la chiffre avec la clé publique du client,
- Le client reçoit le challenge et le décrypte avec la partie privée de sa clé. Il combine le challenge avec l'identifiant de session et chiffre le résultat. Ensuite il envoie le résultat chiffré au serveur.
- Le serveur génère le même haché et le compare avec celui reçu du client. Si les deux hachés sont identiques, l'authentification est réussie.
Configuration du Serveur
La configuration du serveur s'effectue dans le fichier /etc/ssh/sshd_config :
[root@centos8 ~]# cat /etc/ssh/sshd_config # $OpenBSD: sshd_config,v 1.103 2018/04/09 20:41:22 tj Exp $ # This is the sshd server system-wide configuration file. See # sshd_config(5) for more information. # This sshd was compiled with PATH=/usr/local/bin:/usr/bin:/usr/local/sbin:/usr/sbin # 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. # If you want to change the port on a SELinux system, you have to tell # SELinux about this change. # semanage port -a -t ssh_port_t -p tcp #PORTNUMBER # #Port 22 #AddressFamily any #ListenAddress 0.0.0.0 #ListenAddress :: HostKey /etc/ssh/ssh_host_rsa_key HostKey /etc/ssh/ssh_host_ecdsa_key HostKey /etc/ssh/ssh_host_ed25519_key # Ciphers and keying #RekeyLimit default none # This system is following system-wide crypto policy. The changes to # crypto properties (Ciphers, MACs, ...) will not have any effect here. # They will be overridden by command-line options passed to the server # on command line. # Please, check manual pages for update-crypto-policies(8) and sshd_config(5). # Logging #SyslogFacility AUTH SyslogFacility AUTHPRIV #LogLevel INFO # Authentication: #LoginGraceTime 2m PermitRootLogin yes #StrictModes yes #MaxAuthTries 6 #MaxSessions 10 #PubkeyAuthentication yes # 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 #AuthorizedPrincipalsFile none #AuthorizedKeysCommand none #AuthorizedKeysCommandUser nobody # 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 # To disable tunneled clear text passwords, change to no here! #PasswordAuthentication yes #PermitEmptyPasswords no PasswordAuthentication yes # Change to no to disable s/key passwords #ChallengeResponseAuthentication yes ChallengeResponseAuthentication no # Kerberos options #KerberosAuthentication no #KerberosOrLocalPasswd yes #KerberosTicketCleanup yes #KerberosGetAFSToken no #KerberosUseKuserok yes # GSSAPI options GSSAPIAuthentication yes GSSAPICleanupCredentials no #GSSAPIStrictAcceptorCheck yes #GSSAPIKeyExchange no #GSSAPIEnablek5users no # Set this to 'yes' to enable PAM authentication, account processing, # 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 #AllowAgentForwarding yes #AllowTcpForwarding yes #GatewayPorts no X11Forwarding yes #X11DisplayOffset 10 #X11UseLocalhost yes #PermitTTY yes # 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 #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 # no default banner path #Banner none # Accept locale-related environment variables 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 # override default of no subsystems Subsystem sftp /usr/libexec/openssh/sftp-server # Example of overriding settings on a per-user basis #Match User anoncvs # X11Forwarding no # AllowTcpForwarding no # PermitTTY no # ForceCommand cvs server
Pour ôter les lignes de commentaires dans ce fichier, utilisez la commande suivante :
[root@centos8 ~]# cd /tmp ; grep -E -v '^(#|$)' /etc/ssh/sshd_config > sshd_config [root@centos8 tmp]# cat sshd_config 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 X11Forwarding 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
Pour sécuriser le serveur ssh, ajoutez ou modifiez les directives suivantes :
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
Votre fichier ressemblera à celui-ci :
[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 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
Renommez le fichier /etc/ssh/sshd_config en /etc/ssh/sshd_config.old :
[root@centos8 tmp]# cp /etc/ssh/sshd_config /etc/ssh/sshd_config.old
Copiez le fichier /tmp/sshd_config vers /etc/ssh/ :
[root@centos8 tmp]# cp /tmp/sshd_config /etc/ssh cp: overwrite '/etc/ssh/sshd_config'? y
Redémarrez le service sshd :
[root@centos8 tmp]# systemctl restart sshd
[root@centos8 tmp]# systemctl status sshd
● 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...
Aug 30 02:17:00 centos8.ittraining.loc sshd[1042039]: Server listening on 0.0.0.0 port 22.
Aug 30 02:17:00 centos8.ittraining.loc sshd[1042039]: Server listening on :: port 22.
Aug 30 02:17:00 centos8.ittraining.loc systemd[1]: Started OpenSSH server daemon.
[q]
Mettez l'utilisateur trainee dans le groupe adm :
[root@centos8 tmp]# groups trainee trainee : trainee [root@centos8 tmp]# usermod -aG adm trainee [root@centos8 tmp]# groups trainee trainee : trainee adm
Pour générer les clefs du serveur, saisissez la commande suivante en tant que root. Notez que la passphrase doit être vide.
[root@centos8 tmp]# ssh-keygen -t dsa Generating public/private dsa key pair. Enter file in which to save the key (/root/.ssh/id_dsa): /etc/ssh/ssh_host_dsa_key Enter passphrase (empty for no passphrase): Enter same passphrase again: Your identification has been saved in /etc/ssh/ssh_host_dsa_key. Your public key has been saved in /etc/ssh/ssh_host_dsa_key.pub. The key fingerprint is: SHA256:dywC6jKyIMaTxsaEamz1kmthEmuG18HxmS22qRICOYk root@centos8.ittraining.loc The key's randomart image is: +---[DSA 1024]----+ | | | . | |.o . o.+ | |E. o.*.. . | |+ooo.o +S o o | |X==++ o o o | |B/=+oo | |Ooo++ | |. .o | +----[SHA256]-----+
De la même façon, il est possible de générer les clefs au format RSA, ECDSA et ED25519 :
[root@centos8 tmp]# ssh-keygen -t rsa Generating public/private rsa key pair. Enter file in which to save the key (/root/.ssh/id_rsa): /etc/ssh/ssh_host_rsa_key Enter passphrase (empty for no passphrase): Enter same passphrase again: Your identification has been saved in /etc/ssh/ssh_host_rsa_key. 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]-----+
Les clefs publiques générées possèdent l'extension .pub. Les clefs privées n'ont pas d'extension :
[root@centos8 tmp]# ls /etc/ssh moduli ssh_config.d sshd_config.old ssh_host_ecdsa_key.pub ssh_host_ed25519_key.pub ssh_host_rsa_key.pub ssh_config sshd_config ssh_host_ecdsa_key ssh_host_ed25519_key ssh_host_rsa_key
Re-démarrez ensuite le service sshd :
[root@centos8 tmp]# systemctl restart sshd.service
[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>
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.
Aug 30 02:24:57 centos8.ittraining.loc sshd[1042204]: Server listening on :: port 22.
Aug 30 02:24:57 centos8.ittraining.loc systemd[1]: Started OpenSSH server daemon.
[q]
Configuration du Client
Saisissez maintenant les commandes suivantes en tant que trainee :
Important - Lors de la génération des clefs, la passphrase doit être vide.
[root@centos8 tmp]# exit 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. Enter file in which to save the key (/home/trainee/.ssh/id_rsa): Enter passphrase (empty for no passphrase): Enter same passphrase again: Your identification has been saved in /home/trainee/.ssh/id_rsa. Your public key has been saved in /home/trainee/.ssh/id_rsa.pub. The key fingerprint is: 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]-----+
Les clés générées seront placées dans le répertoire ~/.ssh/ :
[trainee@centos8 ~]$ ls .ssh id_dsa id_dsa.pub id_ecdsa id_ecdsa.pub id_ed25519 id_ed25519.pub id_rsa id_rsa.pub
Tunnels SSH
Le protocole SSH peut être utilisé pour sécuriser les protocoles tels telnet, pop3 etc.. En effet, on peut créer un tunnel SSH dans lequel passe les communications du protocole non-sécurisé.
La commande pour créer un tunnel ssh prend la forme suivante :
ssh -N -f compte@hôte -Lport-local:localhost:port_distant
Dans votre cas, vous allez créer un tunnel dans votre propre vm entre le port 15023 et le port 23 :
[root@centos8 ~]# ssh -N -f trainee@localhost -L15023:localhost:23 \S Kernel \r on an \m trainee@localhost's password: trainee
Installez maintenant le serveur telnet :
[root@centos8 ~]# dnf install telnet-server
Telnet n'est ni démarré ni activé. Il convient donc de le démarrer et de l'activer :
[root@centos8 ~]# systemctl status telnet.socket
● telnet.socket - Telnet Server Activation Socket
Loaded: loaded (/usr/lib/systemd/system/telnet.socket; disabled; vendor preset: disabled)
Active: inactive (dead)
Docs: man:telnetd(8)
Listen: [::]:23 (Stream)
Accepted: 0; Connected: 0;
[root@centos8 ~]# systemctl start telnet.socket
[root@centos8 ~]# systemctl status telnet.socket
● telnet.socket - Telnet Server Activation Socket
Loaded: loaded (/usr/lib/systemd/system/telnet.socket; disabled; vendor preset: disabled)
Active: active (listening) since Mon 2021-08-30 02:44:01 EDT; 4s ago
Docs: man:telnetd(8)
Listen: [::]:23 (Stream)
Accepted: 0; Connected: 0;
CGroup: /system.slice/telnet.socket
Aug 30 02:44:01 centos8.ittraining.loc systemd[1]: Listening on Telnet Server Activation Socket.
[root@centos8 ~]# systemctl enable telnet.socket
Created symlink /etc/systemd/system/sockets.target.wants/telnet.socket → /usr/lib/systemd/system/telnet.socket.
Connectez-vous ensuite via telnet sur le port 15023, vous constaterez que votre connexion n'aboutit pas :
[root@centos8 ~]# telnet localhost 15023 Trying ::1... Connected to localhost. Escape character is '^]'. Kernel 4.18.0-305.7.1.el8.i2tch.x86_64 on an x86_64 centos8 login: trainee Password: Last login: Mon Aug 30 02:37:00 from ::1 [trainee@centos8 ~]$ whoami trainee [trainee@centos8 ~]$ pwd /home/trainee
Important - Notez bien que votre communication telnet passe par le tunnel SSH.
3.5 - SCP
Présentation
La commande scp est le successeur et la remplaçante de la commande rcp de la famille des commandes remote. Il permet de faire des transferts sécurisés à partir d'une machine distante :
$ scp compte@numero_ip(nom_de_machine):/chemin_distant/fichier_distant /chemin_local/fichier_local
ou vers une machine distante :
$ scp /chemin_local/fichier_local compte@numero_ip(nom_de_machine):/chemin_distant/fichier_distant
Utilisation
Nous allons maintenant utiliser scp pour chercher un fichier sur le «serveur» :
Créez le fichier /home/trainee/scp_test :
[trainee@centos8 ~]$ touch scp-test [trainee@centos8 ~]$ exit logout Connection closed by foreign host. [root@centos8 ~]#
Récupérez le fichier scp_test en utilisant scp :
[root@centos8 ~]# scp trainee@127.0.0.1:/home/trainee/scp-test . The authenticity of host '127.0.0.1 (127.0.0.1)' 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 '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 scp-test 100% 0 0.0KB/s 00:00 [root@centos8 ~]# ls -l total 32 -rw-------. 1 root root 1358 Jun 16 06:40 anaconda-ks.cfg drwxr-xr-x. 3 root root 21 Jun 16 06:39 home -rw-r--r--. 1 root root 1749 Aug 24 11:20 I2TCH.asc -rw-r--r--. 1 root root 1853 Jun 16 06:54 initial-setup-ks.cfg -rw-r--r--. 1 root root 31 Aug 24 11:22 message.txt -rw-r--r--. 1 root root 561 Aug 24 11:32 message.txt.asc -rw-r--r--. 1 root root 367 Aug 24 11:30 message.txt.gpg -rw-r--r--. 1 root root 329 Aug 24 11:23 message.txt.sig -rw-r--r--. 1 root root 0 Aug 30 03:55 scp-test -rw-r--r--. 1 root root 46 Aug 29 06:22 wget_file.txt
3.6 - Mise en Place des Clefs Asymétriques
Il convient maintenant de se connecter sur le «serveur» en utilisant ssh et vérifiez la présence du répertoire ~/.ssh :
[root@centos8 ~]# ssh -l trainee 127.0.0.1 \S Kernel \r on an \m trainee@127.0.0.1's password: trainee Activate the web console with: systemctl enable --now cockpit.socket [trainee@centos8 ~]$ ls -la | grep .ssh drwx------. 2 trainee trainee 4096 Aug 30 02:26 .ssh
Important - Si le dossier distant .ssh n'existe pas dans le répertoire personnel de l'utilisateur connecté, il faut le créer avec des permissions de 700. Dans votre cas, puisque votre machine joue le rôle de serveur et du client, le dossier /home/trainee/.ssh existe déjà.
Ensuite, il convient de transférer le fichier local .ssh/id_ecdsa.pub du «client» vers le «serveur» en le renommant en authorized_keys :
[trainee@centos8 ~]$ exit logout Connection to 127.0.0.1 closed. [root@centos8 ~]# exit logout [trainee@centos8 ~]$ scp .ssh/id_ecdsa.pub trainee@127.0.0.1:/home/trainee/.ssh/authorized_keys The authenticity of host '127.0.0.1 (127.0.0.1)' 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 '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
Connectez-vous via telnet :
[trainee@centos8 ~]$ ssh -l trainee localhost 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 Last login: Mon Aug 30 03:57:14 2021 from 127.0.0.1 [trainee@centos8 ~]$
Important - Lors de la connexion au serveur, l'authentification utilise le couple de clefs asymétrique au format ecdsa et aucun mot de passe n'est requis.
Insérez maintenant les clefs publiques restantes dans le fichier .ssh/authorized_keys :
[trainee@centos8 ~]$ cd .ssh [trainee@centos8 .ssh]$ ls authorized_keys id_dsa id_dsa.pub id_ecdsa id_ecdsa.pub id_ed25519 id_ed25519.pub id_rsa id_rsa.pub known_hosts [trainee@centos8 .ssh]$ cat authorized_keys ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBHDrzSXP+Ecxf/sQ18VwCRNm7rrSrrsaJmuIw/RgTH5puKF5E+Yy15cvAAKBXpJPxUmrOaOyhab84PevV7XSHcI= trainee@centos8.ittraining.loc [trainee@centos8 .ssh]$ cat id_rsa.pub >> authorized_keys [trainee@centos8 .ssh]$ cat id_dsa.pub >> authorized_keys [trainee@centos8 .ssh]$ cat id_ed25519.pub >> authorized_keys [trainee@centos8 .ssh]$ cat authorized_keys ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBHDrzSXP+Ecxf/sQ18VwCRNm7rrSrrsaJmuIw/RgTH5puKF5E+Yy15cvAAKBXpJPxUmrOaOyhab84PevV7XSHcI= trainee@centos8.ittraining.loc ssh-rsa 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 trainee@centos8.ittraining.loc ssh-dss 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 trainee@centos8.ittraining.loc ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIOfFQULLU8IZyKiSU63D2Zz6yGLqyHcBHnCRdSR9JSmc trainee@centos8.ittraining.loc
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