Set Multiple IP Addresses on the same NIC (Network Interface Card) on Linux

At times we need multiple IP addresses. But what if we have only a single network interface card (NIC)? Well, we can set up multiple IP addresses on the same NIC. Follow along to see how.

Let's say I have an Ethernet interface enp0s3 with the IP address 10.0.2.15. Now I want to add another IP address to the interface. Let's say the new IP address is 10.0.2.18.

Before Adding the Secondary IP Address:

sudo ip addr show enp0s3

2: enp0s3:  mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 08:00:27:45:4e:87 brd ff:ff:ff:ff:ff:ff
    inet 10.0.2.15/24 brd 10.0.2.255 scope global dynamic enp0s3
       valid_lft 86402sec preferred_lft 86402sec
    inet6 fe80::a00:27ff:fe45:4e87/64 scope link 
       valid_lft forever preferred_lft forever

To add another IP address, use the following command,

sudo ip addr add dev enp0s3 10.0.2.18/24

Here 10.0.2.18 is the new IP address and /24 is the subnet mask. enp0s3 is the interface that we want the IP address to be added to.

After Adding the Secondary IP Address:

sudo ip addr show enp0s3

2: enp0s3:  mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 08:00:27:45:4e:87 brd ff:ff:ff:ff:ff:ff
    inet 10.0.2.15/24 brd 10.0.2.255 scope global dynamic enp0s3
       valid_lft 86219sec preferred_lft 86219sec
    inet 10.0.2.18/24 scope global secondary enp0s3
       valid_lft forever preferred_lft forever
    inet6 fe80::a00:27ff:fe45:4e87/64 scope link 
       valid_lft forever preferred_lft forever

From the output, you can see that the new IP address has been added. Now let's try to ping to the IP addresses.

Checking Connectivity:

ping 10.0.2.15

PING 10.0.2.15 (10.0.2.15) 56(84) bytes of data.
64 bytes from 10.0.2.15: icmp_seq=1 ttl=64 time=0.098 ms
64 bytes from 10.0.2.15: icmp_seq=2 ttl=64 time=0.132 ms
64 bytes from 10.0.2.15: icmp_seq=3 ttl=64 time=0.065 ms
64 bytes from 10.0.2.15: icmp_seq=4 ttl=64 time=0.239 ms
64 bytes from 10.0.2.15: icmp_seq=5 ttl=64 time=0.054 ms
64 bytes from 10.0.2.15: icmp_seq=6 ttl=64 time=0.053 ms
64 bytes from 10.0.2.15: icmp_seq=7 ttl=64 time=0.121 ms
64 bytes from 10.0.2.15: icmp_seq=8 ttl=64 time=0.124 ms
^C
--- 10.0.2.15 ping statistics ---
8 packets transmitted, 8 received, 0% packet loss, time 7007ms
rtt min/avg/max/mdev = 0.053/0.110/0.239/0.058 ms

ping 10.0.2.18

PING 10.0.2.18 (10.0.2.18) 56(84) bytes of data.
64 bytes from 10.0.2.18: icmp_seq=1 ttl=64 time=0.117 ms
64 bytes from 10.0.2.18: icmp_seq=2 ttl=64 time=0.113 ms
64 bytes from 10.0.2.18: icmp_seq=3 ttl=64 time=0.111 ms
64 bytes from 10.0.2.18: icmp_seq=4 ttl=64 time=0.134 ms
64 bytes from 10.0.2.18: icmp_seq=5 ttl=64 time=0.113 ms
^C
--- 10.0.2.18 ping statistics ---
5 packets transmitted, 5 received, 0% packet loss, time 4000ms
rtt min/avg/max/mdev = 0.111/0.117/0.134/0.014 ms

Both the IP addresses can be pinged. Everything is working as expected.