Linux ip Command and Examples

Linux ip command is a command-line utility used for show/update ip address, kernel routing tables, network devices, interfaces, and tunnels. This command is a part of iproute2 package. With the help of ip command, the system administrators assign an address to a network interface and/or configure network parameters on an interface.

IP (Internet Protocol) address is a numerical label assigned to a network interface of a computer that allows the communication of the system over the internet. On a computer network, a system communicates with another system by its IP address.

The older operating systems were uses the ifconfig. Which was also a powerful command, is deprecated on newer Linux systems, and replaced by the ip command. But, You can also use the ifconfig command on modern OS/Distros by installing net-tools package..

In this tutorial, you will learn about the uses of the Linux ip command with useful examples.

How to Use ip Command

The modern Linux systems provide iproute2 package, which replaces the various commands provided by the net-tools package. Also, the ip command comes under this packages, with great features.

Syntax:

The ip command uses the following syntax:

ip [ OPTIONS ] OBJECT { COMMAND | help }

Remember that configurations created with this command like IP addresses, routes, and policy routing rules (and so on) are not persistent. Make changes permanently, you need to edit the appropriate configuration to your platform/OS.

Get Help

Just type “help” after the ip command to view commands uses details.

ip help 

Output:
Usage: ip [ OPTIONS ] OBJECT { COMMAND | help }
       ip [ -force ] -batch filename
where  OBJECT := { link | address | addrlabel | route | rule | neigh | ntable |
                   tunnel | tuntap | maddress | mroute | mrule | monitor | xfrm |
                   netns | l2tp | fou | macsec | tcp_metrics | token | netconf | ila |
                   vrf | sr | nexthop }
       OPTIONS := { -V[ersion] | -s[tatistics] | -d[etails] | -r[esolve] |
                    -h[uman-readable] | -iec | -j[son] | -p[retty] |
                    -f[amily] { inet | inet6 | mpls | bridge | link } |
                    -4 | -6 | -I | -D | -M | -B | -0 |
                    -l[oops] { maximum-addr-flush-attempts } | -br[ief] |
                    -o[neline] | -t[imestamp] | -ts[hort] | -b[atch] [filename] |
                    -rc[vbuf] [size] | -n[etns] name | -N[umeric] | -a[ll] |
                    -c[olor]}

In addition, use the help command to get object specific help, like:

ip addr help 

Similarly, try below command to get help for route object subcommand.

ip route help 

Try the help command with other objects to get help.

Next, you will learn about the uses of the ip command. For the learning purpose, use a system physically accessible. In other words, any wrong command may down the network interface and you may disconnect from the remote systems. But, the physical system still be accessible.

View and Manage Network Interfaces

Use link subcommand with ip command to manage and display the state of all network interfaces. The Name of the network interfaces may differ based on the Linux distributions and hardware platforms etc.

1. View all available network interfaces

   The ip link default command shows the details of all interfaces.

   ip link 
   [OR]
   ip link show 
   

   Output:
   1: lo:  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:  mtu 1500 qdisc fq_codel state UP mode DEFAULT group default qlen 1000
       link/ether 6e:dc:96:05:82:a8 brd ff:ff:ff:ff:ff:ff
   

2. View specific network interfaces

   Define the network interface name to view information about the specific one.

   ip link show eth0
   

   Output:
   2: eth0:  mtu 1500 qdisc fq_codel state UP mode DEFAULT group default qlen 1000
       link/ether 6e:dc:96:05:82:a8 brd ff:ff:ff:ff:ff:ff
   
   

3. View statics of a network interface

   Use -s option to view the network interface statics. It shows all details about the packet and data sent and receive on that interface.

   ip -s link show eth0
   

   Output:
   2: eth0:  mtu 1500 qdisc fq_codel state UP mode DEFAULT group default qlen 1000
       link/ether 6e:dc:96:05:82:a8 brd ff:ff:ff:ff:ff:ff
       RX: bytes  packets  errors  dropped overrun mcast
       5746680521 36516527 0       0       0       0
       TX: bytes  packets  errors  dropped carrier collsns
       33339856329 33119340 0       0       0       0
   

   Remove the interface name (eth0) to view statics for all the available network interfaces.

4. Bring UP and Down Network Interfaces

   Use the ip link set command to alter the network interface state. Here up is used to bring the network interface online.

   ip link set eth0 up
   

   Use down option to bring the network interface offline

   ip link set eth0 down
   

   Note: While working with remote systems, don’t bring down the interface. It may disconnect your system from the network.

Display and Add IP Address on Network Interfaces

The ip addr subcommand is used for displaying the IP address configured on network interfaces. You can also use the same command to set an IP address on a network interface.

1. Display IP Address of all interfaces

   The default ip addr subcommand shows the IP addresses details on all interfaces. You can also include show is optional, while viewing the IP details of all network interface.

   ip addr 
   [OR]
   ip addr show 
   

   Output:
   1: lo:  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
       inet6 ::1/128 scope host
          valid_lft forever preferred_lft forever
   2: eth0:  mtu 1500 qdisc fq_codel state UP group default qlen 1000
       link/ether 6e:dc:96:05:82:a8 brd ff:ff:ff:ff:ff:ff
       inet 192.168.10.110/24 brd 192.168.10.255 scope global eth0
          valid_lft forever preferred_lft forever
       inet6 fe80::6cdc:96ff:fe05:82a8/64 scope link
          valid_lft forever preferred_lft forever
   

   You can also display only IPv4 or IPv6 ip addresses by using ip -4 addr or ip -6 addr commands.

2. Display IP address of a single interface:

   Specify the interface name with ip addr show subcommand to display IP address of a specific interface.

   For example, view the IP address on eth0 network interface:

   ip addr show dev eth0
   

   Output:
   2: eth0:  mtu 1500 qdisc fq_codel state UP group default qlen 1000
       link/ether 6e:dc:96:05:82:a8 brd ff:ff:ff:ff:ff:ff
       inet 192.168.10.110/24 brd 192.168.10.255 scope global eth0
          valid_lft forever preferred_lft forever
       inet6 fe80::6cdc:96ff:fe05:82a8/64 scope link
          valid_lft forever preferred_lft forever
   

3. Assing IP address of an interface:

   The ip addr add subcommand is used to add an address on a network interface. The below command will assign ip address 192.168.10.100 with netmask 24 on eth0 network interface.

   ip addr add 192.168.10.100/24 dev eth0
   

4. Assing multiple IP address of an interface:

   In addition, you can assign more IP address to a single interface. Use same command as abvoe to assign multiple IP address on the single network interface. For example:

   ip addr add 192.168.10.100/24 dev eth0
   ip addr add 192.168.10.105/24 dev eth0
   

5. Remove IP address from interface:

   If you think, that an IP address is no more required or adding by mistake can be removed from the interface. Use the ip addr del subcommand to delete an IP address from any network interface.

   For example, use the following command to remove IP address 192.168.10.105 with 24 subnet mask from eth0 interface

   ip addr del 192.168.10.105/24 dev eth0
   

Display and Alter the Routing Table

The ip command also provides you the option to view or change the routing table of any network interface.

Use ip route subcommand to work with the routing tables.

1. List kernel routing table

   By default ip route command lists all the routing entries in the kernel. You can also prefix show option to view the same results.

   ip route 
   

   Output:
   default via 192.168.10.1 dev eth0 proto static
   192.168.10.0/24 dev eth0 proto kernel scope link src 192.168.10.1
   

   The above results show that 192.168.10.1 is the default gateway used by the kernel via the eth0 network interface.

2. Add an entry to the routing table

   • Add a default route (for all addresses) via the local gateway 192.168.10.1 that can be reached on device eth0

     ip route add default via 192.168.10.1 dev eth0 
     

   • Add a route to 192.168.10.0/24 via the gateway at 192.168.10.1

     ip route add 192.168.10.0/24 via 192.168.10.1 
     

   • Add a route to 192.168.10.0/24 that can be reached on device eth0

     ip route add 192.168.10.0/24 dev eth0 
     

3. Delete a routing table entry

   Use the following command to delete the route for 192.168.10.0/24 via the gateway at 192.168.10.1

   ip route delete 192.168.10.0/24 via 192.168.10.1 
   

4. Replace, or add if not defined, a route

   Replace an exiting route defined for 192.168.10.0/24 to use device eth0

   ip route replace 192.168.10.0/24 dev em1 
   

5. Display the route an address will take

   This command is very useful during the troubleshooting of the network. In other words, you can find the route used by the system to reach a defined destination IP address.

   ip route get 8.8.8.8 
   

   Output:
   8.8.8.8 via 192.168.10.1 dev eth0 src 192.168.10.108 uid 0
   

Conclusion

In conclusion, you have learned about Linux ip command with useful examples. Here we describe, how to manage a network interface on Linux systems. Adding or deleting the kernel routing table entries. Make a network interface UP (online) and down (offline). Adding, remove or display the IP addresses on a network interface.