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tech:notes_diag_reseau [2025/11/11 22:56] – Jean-Baptistetech:notes_diag_reseau [2026/06/07 19:12] (Version actuelle) – modification externe 127.0.0.1
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 +<!DOCTYPE markdown>
 +{{tag>Brouillon Réseau}}
 +
 +# Notes diag réseau
 +
 +Commande **ip** https://access.redhat.com/sites/default/files/attachments/rh_ip_command_cheatsheet_1214_jcs_print.pdf
 +
 +Diag
 +
 +~~~bash
 +ifstat
 +ss -s
 +ss -peaonmi
 +# sar -n DEV
 +sar -n ALL
 +networkctl
 +~~~
 +
 +~~~bash
 +networkctl list
 +~~~
 +
 +~~~bash
 +ip -4 -o addr
 +~~~
 +
 +Only up
 +~~~
 +$ ip link ls up
 +
 +1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default 
 +    inet 127.0.0.1/8 scope host lo
 +       valid_lft forever preferred_lft forever
 +~~~
 +
 +~~~
 +$ ip -0 addr
 +1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default 
 +    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
 +2: eth0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN group default qlen 1000
 +    link/ether 14:da:e9:a6:da:ca brd ff:ff:ff:ff:ff:ff
 +3: wlan0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc mq state DOWN group default qlen 1000
 +    link/ether 74:2f:68:4b:6c:41 brd ff:ff:ff:ff:ff:ff
 +~~~
 +
 +~~~
 +# cat /sys/class/net/eth0/speed
 +1000
 +~~~
 +
 +
 +~~~
 +# cat /sys/class/net/eth0/duplex
 +full
 +~~~
 +
 +
 +Lister toutes les interfaces branchées 
 +~~~
 +# grep 1 /sys/class/net/*/carrier
 +/sys/class/net/eth0/carrier:1
 +/sys/class/net/eth1/carrier:1
 +/sys/class/net/eth2/carrier:1
 +/sys/class/net/eth3/carrier:1
 +/sys/class/net/lo/carrier:1
 +~~~
 +
 +~~~bash
 +ethtool eth0
 +~~~
 +
 +~~~
 +Settings for eth0:
 + Supported ports: [ TP MII ]
 + Supported link modes:   10baseT/Half 10baseT/Full 
 +                         100baseT/Half 100baseT/Full 
 +                         1000baseT/Half 1000baseT/Full 
 + Supported pause frame use: No
 + Supports auto-negotiation: Yes
 + Advertised link modes:  10baseT/Half 10baseT/Full 
 +                         100baseT/Half 100baseT/Full 
 +                         1000baseT/Half 1000baseT/Full 
 + Advertised pause frame use: Symmetric Receive-only
 + Advertised auto-negotiation: Yes
 + Speed: 10Mb/s
 + Duplex: Half
 + Port: MII
 + PHYAD: 0
 + Transceiver: internal
 + Auto-negotiation: on
 + Supports Wake-on: pumbg
 + Wake-on: d
 + Current message level: 0x00000033 (51)
 +        drv probe ifdown ifup
 + Link detected: no
 +~~~
 +
 +Si pas de `ethtool`, essayer `mii-tool`
 +
 +~~~bash
 +# mii-tool eth0
 +eth0: no link
 +~~~
 +
 +On arrête le "network-manager" car nous allons configurer le réseau manuellement
 +~~~bash
 +service network-manager stop
 +~~~
 +
 +Demande d'un bail DHCP (DHCP OFFER)
 +~~~bash
 +dhclient eth0
 +~~~
 +
 +Parfois il faut faire un `dhclient -r` avant pour que ça fonctionne.
 +~~~bash
 +dhclient -r eth0
 +dhclient eth0
 +~~~
 +
 +Si rien ne se passe `Ctrl + c`. C'est qu'on ne parviens pas à avoir une réponse du serveur DHCP.
 +
 +Statistic
 +~~~bash
 +ip -s link show eth0
 +~~~
 +
 +
 +
 +## Changer l'adresse ip avec iproute2 (ip)
 +
 +
 +
 +Effacement de l’ancienne adresse ipv4 
 +~~~bash
 +ip -4 a del dev eth0
 +~~~
 +
 +Nous pouvons définir manuellement l'adresse IP :
 +~~~bash
 +#ifconfig eth0 192.168.1.12 netmask 255.255.255.0 up
 +ip addr add 192.168.1.12/24 dev eth0
 +ip link set eth0 up
 +~~~
 +
 +
 +## Définir la route / passerelle par défaut
 +
 +Voir la table de routage
 +~~~bash
 +ip r
 +ip route show table all
 +#ip r show table all | egrep -v "^unreachable|^local|^broadcast"
 +~~~
 +
 +Ajouter une route
 +~~~bash
 +ip route add default via 192.168.1.1
 +~~~
 +
 +Supprimer une passerelle par défaut
 +
 +~~~bash
 +ip route del 0.0.0.0/0 via 192.168.1.1
 +~~~
 +
 +Test / diag / debug du routage
 +~~~bash
 +ip route get 8.8.8.8
 +~~~
 +
 +### Traceroute
 +
 +Voir :
 +* tracepath
 +* https://www.cloudflare.com/fr-fr/learning/network-layer/what-is-mtr/
 +* https://www.cloudflare.com/learning/network-layer/what-is-mtr/
 +
 +Voir aussi : https://en.wikipedia.org/wiki/Source_routing
 +
 +Traceroute avec MTR
 +~~~
 +$ mtr -c 10 --udp 10.33.133.246 -P 88 -rn
 +Start: 2023-07-11T16:55:56+0200
 +HOST: websrv1                     Loss%   Snt   Last   Avg  Best  Wrst StDev
 +  1.|-- 10.230.223.1               0.0%    10    0.2   0.3   0.2   1.0   0.2
 +  2.|-- 10.255.183.12              0.0%    10    0.6   3.1   0.6  11.0   4.3
 +  3.|-- 10.255.29.2                0.0%    10    0.7   1.0   0.6   2.2   0.6
 +  4.|-- 10.154.254.1               0.0%    10   25.4  25.6  25.4  27.1   0.5
 +  5.|-- 10.133.4.178               0.0%    10   25.4  25.6  25.3  26.1   0.3
 +  6.|-- 10.133.4.38                0.0%    10   26.7  26.8  25.7  34.4   2.7
 +  7.|-- ???                       100.0    10    0.0   0.0   0.0   0.0   0.0
 +~~~
 +
 +
 +
 +### Connaître l'adresse MAC d'origine / permanente
 +
 +Certains types d’agrégation de liens (bonding) utilise le changement d'adresse MAC. \\
 +Il peut être utile de retrouver l'@MAC original de la carte.
 +
 +~~~
 +# cat /proc/net/bonding/bond0
 +Ethernet Channel Bonding Driver: v3.7.1 (April 27, 2011)
 +
 +Bonding Mode: fault-tolerance (active-backup)
 +Primary Slave: None
 +Currently Active Slave: eno50
 +MII Status: up
 +MII Polling Interval (ms): 100
 +Up Delay (ms): 0
 +Down Delay (ms): 0
 +
 +Slave Interface: eno49
 +MII Status: down
 +Speed: Unknown
 +Duplex: Unknown
 +Link Failure Count: 0
 +Permanent HW addr: 5c:b9:01:d0:06:d0
 +Slave queue ID: 0
 +
 +Slave Interface: eno50
 +MII Status: up
 +Speed: 10000 Mbps
 +Duplex: full
 +Link Failure Count: 0
 +Permanent HW addr: 5c:b9:01:d0:06:d8
 +Slave queue ID: 0
 +~~~
 +
 +
 +~~~
 +# ethtool -P eno50
 +Permanent address: 5c:b9:01:d0:06:d8
 +~~~
 +
 +ou (si supporté)
 +
 +~~~
 +# cat /sys/class/net/eno50/phys_port_id
 +5cb901d006d8
 +~~~
 +
 +Alors que l'adresse actuelle définie (spoofé) est :
 +~~~
 +# cat /sys/class/net/eno50/address
 +5c:b9:01:d0:06:d0
 +~~~
 +
 +~~~
 +# ip a show dev eno50
 +3: eno50: <BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP> mtu 1500 qdisc mq master bond0 state UP qlen 1000
 +    link/ether 5c:b9:01:d0:06:d0 brd ff:ff:ff:ff:ff:ff
 +~~~
 +
 +
 +## Exemple conf Debian
 +
 +`/etc/network/interfaces`
 +~~~
 +source /etc/network/interfaces.d/*
 +
 +# The loopback network interface
 +auto lo
 +iface lo inet loopback
 +
 +# The primary network interface
 +allow-hotplug eth0
 +iface eth0 inet dhcp
 +
 +auto eth1
 +iface eth1 inet static
 +        address 192.168.56.12
 +        netmask 255.255.255.0
 +        gateway 192.168.56.1
 +        
 +allow-hotplug eth2
 +iface eth2 inet static
 +        address 10.240.100.101
 +        netmask 255.255.255.0
 +        network 10.240.100.0
 +        broadcast 10.240.100.255
 +        gateway 10.240.100.250
 +        # dns-* options are implemented by the resolvconf package, if installed
 +        dns-search localdomain
 +        dns-nameservers 8.8.8.8 8.8.4.4
 +~~~
 +
 +~~~bash
 +#systemctl restart networking
 +ifdown eth0
 +ifup eth0
 +~~~
 +
 +
 +## Exemple conf RedHat
 +
 +Notes : 
 +* A partir de RHEL9 **keyfile** remplace **ifcfg**
 +
 +`/etc/sysconfig/network-scripts/ifcfg-eth0`
 +~~~ini
 +TYPE=Ethernet
 +BOOTPROTO=dhcp
 +#DEFROUTE=no
 +#PEERDNS=no
 +IPV6INIT=no
 +IPV4_FAILURE_FATAL=no
 +NAME=eth0
 +DEVICE=eth0
 +ONBOOT=yes
 +NM_CONTROLLED=no
 +~~~
 +
 +
 +`/etc/sysconfig/network-scripts/ifcfg-eth1`
 +~~~ini
 +DEVICE=eth1
 +BOOTPROTO=none
 +ONBOOT=yes
 +TYPE=Ethernet
 +IPV6INIT=no
 +HWADDR=00:50:56:c4:8d:ae
 +NETMASK=255.255.255.0
 +IPADDR=192.168.10.101
 +GATEWAY=192.168.10.1
 +#MTU=1450
 +~~~
 +
 +~~~bash
 +#systemctl restart network
 +ifdown eth0
 +ifup eth0
 +~~~
 +
 +
 +## Bonding
 +
 +~~~bash
 +ip a | grep bond0
 +cat /proc/net/bonding/bond0
 +~~~
 +
 +
 +Suppression agrégation de liens
 +
 +~~~bash
 +ip link set dev bond0 down
 +ip link del dev bond0
 +~~~
 +
 +
 +## Netplan
 +
 +`/etc/network/interfaces`
 +~~~
 +# ifupdown has been replaced by netplan(5) on this system.  See
 +# /etc/netplan for current configuration.
 +# To re-enable ifupdown on this system, you can run:
 +#    sudo apt install ifupdown
 +~~~
 +
 +
 +`/etc/netplan/01-netcfg.yaml`
 +~~~yaml
 +# This file describes the network interfaces available on your system
 +# For more information, see netplan(5).
 +network:
 +  version: 2
 +  renderer: networkd
 +  ethernets:
 +    ens192:
 +      dhcp4: no
 +      dhcp6: no
 +      addresses:
 +      - 10.15.65.5/24
 +      gateway4: 10.15.65.254
 +      nameservers:
 +        addresses: [192.168.130.11,192.168.131.75]
 +    ens160:
 +      dhcp4: no
 +      dhcp6: no
 +      addresses:
 +      - 192.168.1.105/24
 +      - 2a01:4588:0:fd::109/64
 +      gateway4: 192.168.1.1
 +      gateway6: 2a01:4580:0:fd::1
 +      nameservers:
 +        addresses:
 +        - 46.18.130.11
 +        - 46.18.131.75
 +      routes:
 +      - to: 192.168.255.0/24
 +        via: 192.168.1.1
 +~~~
 +
 +Pour vérifier la config
 +~~~bash
 +netplan try
 +
 +# Rien de sera appliqué si --debug
 +netplan --debug apply
 +~~~
 +
 +Si OK pour appliquer
 +~~~bash
 +netplan apply
 +~~~
 +
 +
 +~~~
 +     netplan generate: Use /etc/netplan to generate the required
 +configuration for the renderers.
 +     netplan apply: Apply all configuration for the renderers,
 +restarting them as necessary.
 +~~~
 +
 +~~~bash
 +# pour vérifier que la syntaxe était bonne, puis
 +netplan --debug generate
 +
 +netplan generate 
 +netplan apply
 +
 +man 5 netplan
 +~~~
 +
 +
 +## Network-Manager UI
 +
 +Liste :
 +* connman / cmst
 +* wicd
 +* nm-tray / network-manager
 +
 +
 +## Promiscuous mode
 +
 +~~~bash
 +ip link set eth0 promisc on
 +~~~
 +
 +
 +## Autres 
 +
 +Voir :
 +* `/etc/resolvconf/resolv.conf.d/head`
 +
 +
 +## Perte de paquets ?
 +
 +
 +~~~
 +netstat -s | grep retransmitted
 +     368644 segments retransmitted
 +
 +netstat -s | grep segments
 +         149840 segments received
 +         150373 segments sent out
 +         161 segments retransmitted
 +         13 bad segments received
 +~~~
 +
 +
 +## Err
 +
 +~~~
 +# systemctl restart network
 +RTNETLINK answers: File exists
 +~~~
 +
 +Solution
 +~~~bash
 +systemctl stop NetworkManager
 +#ip addr flush dev eth1
 +#ps -ef | grep -i net
 +~~~
 +
 +
 +Autres
 +~~~bash
 +ethtool -K ens33 tx-checksum-ip-generic off
 +~~~
 +
  
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