Linux:Network
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Checks
Common
# List route table route -n # Display network connections and current states netstat # Check listening ports, connected remote IPs, processes, states and more netstat -taupen # Check listening ports and IPs of the local server netstat -tulpn # List the routing table netstat -r # List verbose common TCP and ICMP information netstat -s # List iptable rules (Nftables) iptables -nvL # List iptable rules (Legacy iptables) iptables-legacy -nvL # Test specific IP and port combination for connectivity telnet 172.16.2.1 22 # Wireshark on a specific interface to a file, listening on a local port and for a remote IP tshark -p -i bond0 -w file.pcap -f "port 443 and host 172.16.16.25" # List available routers ip netns # Show interfaces with an IPv4 address ip -4 a # Show interfaces with an IPv6 address ip -6 a
Network
NetworkManager
nmtui is a GUI-tool for managing NetworkManager connections.
Checks
# Show all active network connections nmcli connection show # Show connection information for interface ens5 nmcli connection show ens5 # Show active and unactive network connections nmcli dev status
nmcli
# Bring logical interface ens6 up nmcli device up ens6 # Turn off DHCP nmcli con mod ens6 ipv4.method manual nmcli con mod ens6 connection.autoconnect yes # Add an IP-address to interface ens6 nmcli connection modify ens6 ipv4.address "192.168.0.10/24" # Add DNS-servers to interface ens6 nmcli connection modify ens6 ipv4.dns "8.8.8.8,1.1.1.1,196.168.0.1" # Add a gateway to interface ens6 nmcli con mod ens6 ipv4.gateway "192.168.0.1" # Add a default route to interface ens160 nmcli connection modify ens160 +ipv4.routes "0.0.0.0/0 192.168.3.100" # Remove an IP-address from interface ens6 nmcli con mod ens6 -ipv4.addresses 192.168.0.11/24 # Apply changes to interface ens nmcli device reapply ens6
RHEL
Generic Interface
BOOTPROTO=static for static address
BOOTPROTO=dhcp for DHCP
# /etc/sysconfig/network-scripts/ifcfg-ens128 DEVICE=ens128 NAME=ens128 HWADDR=ab:cd:ef:gh:ij:kl UUID=0a8d3485-d512-46da-8225-19f4721813c1 BOOTPROTO=static STARTMODE=auto ONBOOT=yes IPADDR=192.168.10.2 NETMASK=255.255.255.0 GATEWAY=192.168.10.1
Generic VLAN Interface
# /etc/sysconfig/network-scripts/ifcfg-eno2.100 VLAN=yes TYPE=Vlan PHYSDEV=eno2 VLAN_ID=100 NAME=eno2.100 BOOTPROTO=static HWADDR=ab:cd:ef:gh:ij:kl IPADDR=192.168.100.217 NETMASK=255.255.255.0 STARTMODE=auto UUID=689cff6f-c750-4db7-936c-234fb80b6018 GATEWAY=192.168.100.1
VLAN Bond interface configuration
Virtual Bond Master
BONDING_OPTS="mode=802.3ad miimon=100" TYPE=Bond BONDING_MASTER=yes PROXY_METHOD=none BROWSER_ONLY=no IPV6INIT=no NAME=bond0 UUID=7bb91614-6ffe-4bdc-9b37-c6e9d37f6987 DEVICE=bond0 ONBOOT=yes AUTOCONNECT_PRIORITY=9 AUTOCONNECT_RETRIES=0 AUTOCONNECT_SLAVES=yes MTU=1500
Physical bond Slaves
# /etc/sysconfig/network-scripts/ifcfg-ens1 TYPE=Ethernet NAME=ens1 UUID=c6a4da43-b84a-44f4-b49f-4bdc717d4238 DEVICE=ens1 ONBOOT=yes AUTOCONNECT_PRIORITY=9 AUTOCONNECT_RETRIES=0 MASTER_UUID=7bb91614-6ffe-4bdc-9b37-c6e9d37f6987 MASTER=bond0 SLAVE=yes
# /etc/sysconfig/network-scripts/ifcfg-ens2 TYPE=Ethernet NAME=ens2 UUID=ca09a126-a082-4620-a920-be45269e5d8a DEVICE=ens2 ONBOOT=yes AUTOCONNECT_PRIORITY=9 AUTOCONNECT_RETRIES=0 MASTER_UUID=7bb91614-6ffe-4bdc-9b37-c6e9d37f6987 MASTER=bond0 SLAVE=yes
VLAN 100 Interface
# /etc/sysconfig/network-scripts/ifcfg-vlan-bond0.100 VLAN=yes TYPE=Vlan PHYSDEV=bond0 VLAN_ID=100 REORDER_HDR=yes GVRP=no MVRP=no HWADDR= PROXY_METHOD=none BROWSER_ONLY=no BOOTPROTO=none IPADDR=192.168.100.10 PREFIX=24 DEFROUTE=yes IPV4_FAILURE_FATAL=no NAME=vlan-bond0.100 UUID=83b0e31c-9a9f-47da-9dc6-645796bc47aa ONBOOT=yes AUTOCONNECT_PRIORITY=9 AUTOCONNECT_RETRIES=0 GATEWAY=192.168.100.1
Ubuntu/Debian
Netplan
# Apply the configuration, but if the dialogue is left unconfirmed, the configuration will be reverted. netplan try # Apply the configuration netplan apply
Generic DCHP interface
network:
version: 2
ethernets:
ens4:
# Some info about the Interface/why does it exist
dhcp4: true
match:
macaddress: fa:16:3e:aa:bb:cc
set-name: ens4
Generic DHCP Interfaces, but while ignoring the routes for an Interface and disabling DHCP on the other.
network:
version: 2
ethernets:
ens4:
# Some info about the Interface/why does it exist
dhcp4: true
dhcp4-overrides:
use-routes: false
match:
macaddress: fa:16:3e:aa:bb:cc
set-name: ens4
ens5:
# Some info about the Interface/why does it exist
dhcp4: no
match:
macaddress: fa:16:cc:dd:ee
set-name: ens5
Generic static interface
You may have to disable automatic network-configuration:
sudo bash -c 'echo "network: {config: disabled}" > /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg'
network:
version: 2
ethernets:
ens7:
addresses:
- 192.168.0.23/24
match:
macaddress: ab:cd:ef:gh:ij:kl
mtu: 1500
set-name: ens7
nameservers:
addresses: [1.1.1.1, 8.8.8.8]
routes:
- to: default
via: 192.168.0.1
VLAN Interface
network:
version: 2
ethernets:
eno1: {}
vlans:
eno1.10:
id: 10
link: eno1
addresses: [192.168.1.1/24]
eno1.20:
id: 20
link: eno1
addresses: [192.168.2.1/24]
nameservers:
addresses:
- 1.1.1.1
- 8.8.8.8
search: []
routes:
- to: default
via: 192.168.2.1
eno1.30:
id: 30
link: eno1
addresses: [192.168.3.1/24]
Empty Interface
network:
version: 2
ethernets:
eno2:
dhcp4: false
dhcp6: false
Interface files
Classic /etc/network/interfaces.d files i.e. /etc/network/interfaces.d/ens200.conf
Otherwise use /etc/network/interfaces
Generic IPv4
# /etc/network/interfaces.d/ens160.conf
auto ens160
iface ens160 inet static
address 192.168.23.7
netmask 255.255.255.0
gateway 192.168.23.1
Generic IPv6
# /etc/network/interfaces.d/ens3.conf
iface ens3 inet6 static
address abcd:defg:0:1234:5123:abcd:abcd:1234
netmask 48
gateway abcd:defg::1
Bond
auto eno1
iface eno1 inet manual
auto eno2
iface eno2 inet manual
auto bond0
iface bond0 inet static
address 192.168.39.245
gateway 192.168.39.254
network 255.255.255.0
bond-slaves eno1 eno2
bond-miimon 100
bond-mode 802.3ad
bond-xmit-hash-policy layer2+3
