Linux:Network
From Cheatsheet
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
DNS
# Lookup reverse DNS host information dig -x 10.0.2.15 # Lookup reverse DNS host information host 10.0.2.15 # Lookup DNS host information nslookup 10.0.2.15 # Lookup host information for google.com while using DNS-server 8.8.8.8 nslookup google.com 8.8.8.8
Network
NetworkManager
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
# 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 ens18 ipv4.dns "8.8.8.8,1.1.1.1,196.168.0.1" # 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
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: [1.1.1.1.1, 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
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
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
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
