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

address 85.159.209.124

netmask 255.255.255.0

gateway 85.159.209.1
iface eth0:1 inet static

address 109.237.26.62

netmask 255.255.255.0

Save that file, restart networking and then try pinging your new IP address.