I was just asked to add a new IP address to a Debian cloud host. It’s a simple thing, but depending on how often – or how seldom – you do it, you often still need to look it up to remind yourself. So, having previously decided to do a post every time I do something like this (for my own benefit as much as anything) here’s what I did…
Edit `/etc/network/interfaces` – obviously you’ll need to be root or `sudo` it.
There will probably something like this in there:
auto lo
iface lo inet loopback
auto eth0
iface eth0 inet dhcp
The first chunk is the [loopback interface](http://en.wikipedia.org/wiki/Loopback), but the second chunk is the ethernet (`eth0`). The final line might be `dhcp` or it might be `static`, followed by more lines to describe the IP, like this:
iface eth0 inet static
address 209.85.147.147
netmask 255.255.255.255
To add a new IP – let’s imagine it’s ‘209.85.147.148’ – to the same ethernet interface, just add something like this:
iface eth0:0 inet static
address 209.85.147.148
netmask 255.255.255.255
The “`:0`” is the extra bit we added. Then restart your networking:
/etc/init.d/networking restart
(keeping your fingers crossed you didn’t make any mistakes that might then lock you out of your host completely, of course ;)