How to Use IP Command in Linux with Examples?

The IP command is a powerful tool for network configuration in Linux. It is used to show, manipulate routing, devices, policy routing, and tunnels. The IP command is part of the iproute2 package, which is installed by default in most Linux distributions. It replaces legacy tools like ifconfig and route, providing a unified interface for network management.

Displaying IP Addresses

To display the IP address of all network interfaces, use the following command

Example

ip addr show

Output

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
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
   link/ether 08:00:27:15:64:b3 brd ff:ff:ff:ff:ff:ff
   inet 192.168.1.10/24 brd 192.168.1.255 scope global dynamic eth0
      valid_lft 86378sec preferred_lft 86378sec

You can also view a specific interface using ip addr show eth0 or use the short form ip a.

Managing IP Addresses

Adding an IP Address

To add an IP address to a network interface, use the following command

sudo ip addr add 192.168.1.100/24 dev eth0

This command adds the IP address 192.168.1.100 to the network interface eth0. The /24 at the end of the IP address is the subnet mask in CIDR notation.

Deleting an IP Address

To delete an IP address from a network interface, use the following command

sudo ip addr del 192.168.1.100/24 dev eth0

This command removes the IP address 192.168.1.100 from the network interface eth0.

Route Management

Displaying the Routing Table

To display the routing table, use the following command

ip route show

Output

default via 192.168.1.1 dev eth0 proto static 
192.168.1.0/24 dev eth0 proto kernel scope link src 192.168.1.10

Adding a Route

To add a route, use the following command

sudo ip route add 192.168.2.0/24 via 192.168.1.1 dev eth0

This command adds a route to the network 192.168.2.0/24 via the gateway 192.168.1.1 on the network interface eth0.

Deleting a Route

To delete a route, use the following command

sudo ip route del 192.168.2.0/24

Network Interface Management

Displaying Network Interfaces

The ip link show command displays information about the network interfaces

ip link show

Output

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000
    link/ether 08:00:27:15:64:b3 brd ff:ff:ff:ff:ff:ff

Changing Interface State

To change the state of a network interface, use the following commands

sudo ip link set eth0 down
sudo ip link set eth0 up

The first command brings the network interface eth0 down, and the second command brings it back up.

Changing the MTU

To change the Maximum Transmission Unit (MTU) of a network interface

sudo ip link set eth0 mtu 1400

Network Statistics and Information

Displaying Interface Statistics

The ip -s link command displays statistics for the network interfaces

ip -s link

Output

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
   link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
   RX: bytes  packets  errors  dropped overrun mcast   
   166114     1982     0       0       0       0      
   TX: bytes  packets  errors  dropped carrier collsns 
   166114     1982     0       0       0       0 

Displaying Neighbour Table (ARP)

The ip neigh command displays neighbour objects (ARP table)

ip neigh

Output

192.168.1.1 dev eth0 lladdr 00:14:bf:b1:cb:31 REACHABLE

You can add or delete neighbour entries using

sudo ip neigh add 192.168.1.101 lladdr 1:2:3:4:5:6 dev eth0
sudo ip neigh del 192.168.1.101 dev eth0

Network Namespaces

Network namespaces provide isolation of network resources. Each namespace has its own network interfaces, routing tables, and firewall rules.

Managing Namespaces

# List existing namespaces
ip netns

# Create a new namespace
sudo ip netns add mynamespace

# Execute commands in a namespace
sudo ip netns exec mynamespace ip addr

# Delete a namespace
sudo ip netns del mynamespace

Common IP Command Options

Key Features

• Unified Interface Single command for all network operations

• Feature Rich Supports advanced networking features like namespaces and policy routing

• Non-persistent Changes Changes are lost after reboot unless saved to configuration files

• Human and Machine Readable Output can be formatted for scripts using -j (JSON) option

Conclusion

The IP command is a comprehensive tool for Linux network management that replaces legacy utilities. It provides unified access to configure interfaces, routes, and advanced networking features like namespaces. While changes are temporary by default, the IP command is essential for modern Linux network administration and troubleshooting.