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tech:notes_diag_reseau

Ceci est une ancienne révision du document !

Table des matières

,

Notes diag réseau

Commande ip https://access.redhat.com/sites/default/files/attachments/rh_ip_command_cheatsheet_1214_jcs_print.pdf

Diag 

ifstat
ss -s
ss -peaonmi
# sar -n DEV
sar -n ALL
networkctl
networkctl list
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
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 

# mii-tool eth0
eth0: no link

On arrête le “network-manager” car nous allons configurer le réseau manuellement 

service network-manager stop

Demande d'un bail DHCP (DHCP OFFER) 

dhclient eth0

Parfois il faut faire un dhclient -r avant pour que ça fonctionne. 

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 

ip -s link show eth0

Changer l'adresse ip avec iproute2 (ip)

Effacement de l’ancienne adresse ipv4 

ip -4 a del dev eth0

Nous pouvons définir manuellement l'adresse IP : 

#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 

ip r
ip route show table all
#ip r show table all |egrep -v "^unreachable|^local|^broadcast"

Ajouter une route 

ip route add default via 192.168.1.1

Supprimer une passerelle par défaut 

ip route del 0.0.0.0/0 via 192.168.1.1

Test / diag / debug du routage 

ip route get 8.8.8.8

Traceroute

Voir :

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
#systemctl restart networking
ifdown eth0
ifup eth0

Exemple conf RedHat

Notes :

  • A partir de RHEL9 keyfile remplace ifcfg
/etc/sysconfig/network-scripts/ifcfg-eth0
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
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
#systemctl restart network
ifdown eth0
ifup eth0

Bonding

ip a |grep bond0
cat /proc/net/bonding/bond0

Suppression agrégation de liens 

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
# 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 

netplan try
 
# Rien de sera appliqué si --debug
netplan --debug apply

Si OK pour appliquer 

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.
# 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

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 

systemctl stop NetworkManager
#ip addr flush dev eth1
#ps -ef |grep -i net
tech/notes_diag_reseau.1742825205.txt.gz · Dernière modification : de 127.0.0.1
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