Some times you might want to use more than one IP address for your network interface card. What will you do in such cases? Buy an extra network card and assign new IP? No, It’s not necessary(at least in the small networks). We can now assign multiple IP addresses to one interface on Ubuntu systems. Curious to know how? Well, Follow me, It is not that difficult.
This method will work on Debian and it’s derivatives too.
### Add additional IP addresses temporarily ###
First, let us find the IP address of the network card. In my Ubuntu 15.10 server, I use only one network card.
Run the following command to find out the IP address:
sudo ip addr
**Sample output:**
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default
inet 192.168.1.103/24 brd 192.168.1.255 scope global enp0s3
valid_lft forever preferred_lft forever
inet6 fe80::a00:27ff:fe2a:34e/64 scope link
valid_lft forever preferred_lft forever
See, It’s gone!!
Well, as you may know, the changes will lost after you reboot your system. How do I make it permanent? That’s easy too.
### Add additional IP addresses permanently ###
The network card configuration file of your Ubuntu system is **/etc/network/interfaces**.
Let us check the details of the above file.
sudo cat /etc/network/interfaces
**Sample output:**
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).
source /etc/network/interfaces.d/*
# The loopback network interface
auto lo
iface lo inet loopback
# The primary network interface
auto enp0s3
iface enp0s3 inet dhcp
As you see in the above output, the Interface is DHCP enabled.
Okay, now we will assign an additional address, for example **192.168.1.104/24**.
Edit file **/etc/network/interfaces**:
sudo nano /etc/network/interfaces
Add additional IP address as shown in the black letters.
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).
source /etc/network/interfaces.d/*
# The loopback network interface
auto lo
iface lo inet loopback
# The primary network interface
auto enp0s3
iface enp0s3 inet dhcp
iface enp0s3 inet static
address 192.168.1.104/24
Save and close the file.
Run the following file to take effect the changes without rebooting.
sudo ifdown enp0s3 && sudo ifup enp0s3
**Sample output:**
Killed old client process
Internet Systems Consortium DHCP Client 4.3.1
Copyright 2004-2014 Internet Systems Consortium.
All rights reserved.
For info, please visit https://www.isc.org/software/dhcp/
Listening on LPF/enp0s3/08:00:27:2a:03:4e
Sending on LPF/enp0s3/08:00:27:2a:03:4e
Sending on Socket/fallback
DHCPRELEASE on enp0s3 to 192.168.1.1 port 67 (xid=0x225f35)
Internet Systems Consortium DHCP Client 4.3.1
Copyright 2004-2014 Internet Systems Consortium.
All rights reserved.
For info, please visit https://www.isc.org/software/dhcp/
Listening on LPF/enp0s3/08:00:27:2a:03:4e
Sending on LPF/enp0s3/08:00:27:2a:03:4e
Sending on Socket/fallback
DHCPDISCOVER on enp0s3 to 255.255.255.255 port 67 interval 3 (xid=0xdfb94764)
DHCPREQUEST of 192.168.1.103 on enp0s3 to 255.255.255.255 port 67 (xid=0x6447b9df)
DHCPOFFER of 192.168.1.103 from 192.168.1.1
DHCPACK of 192.168.1.103 from 192.168.1.1
bound to 192.168.1.103 -- renewal in 35146 seconds.
**Note**: It is **very important** to run the above two commands into **one** line if you are remoting into the server because the first one will drop your connection. Given in this way the ssh-session will survive.
Now, let us check if IP is added using command:
sudo ip address show enp0s3
**Sample output:**
2: enp0s3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
