Update: I no longer use Linode, but I had this draft laying here, so decided to publish anyhow.
If you have an additional IP address on your Linode Ubuntu box, you’ll need to add it to your
/etc/network/interfaces file, so open that up using
nano or a similar tool, you’ll need to add
eth0:1 to the auto line, then an
iface block, so that it looks similar to this:
# The loopback network interface auto lo eth0 eth0:1 eth0:2 iface lo inet loopback
The primary network interface
iface eth0 inet static
iface eth0:1 inet static
Save that file, restart networking and then try pinging your new IP address.