How to configure an IPFailOver on Debian and ISPConfig 3

If you have a Debian server with ISPConfig 3 installed, here is how to configure one or more IP FailOver addresses.

Debian Configuration

First, you need to configure Debian to add your new IP address.

Connect to your server and edit the file /etc/network/interfaces.

If you have a Debian version higher than 6 (which is usually the case), you will need to add the following two lines for each new IP address you want to add:

post-up /sbin/ifconfig eth0:X IPFailOver netmask 255.255.255.255 broadcast IPFailOver
post-down /sbin/ifconfig eth0:X down

Replace the X after eth0: with 0 for the first IP you are adding, 1 for the second, and so on. Replace "IPFailOver" with the IP address you want to add.

You should end up with a file similar to this:

auto eth0
iface eth0 inet static
 address *.*.*.*
 netmask 255.255.255.0
 network *.*.*.*
 broadcast *.*.*.*
 gateway *.*.*.*
 post-up /sbin/ifconfig eth0:0 *.*.*.* netmask 255.255.255.255 broadcast *.*.*.*
 post-down /sbin/ifconfig eth0:0 down

...

Save the file and execute the following command to apply the updates:

/etc/init.d/networking restart

To verify that everything is working, ping the IP address in question; you should receive a response (which was not the case before).

ISPConfig 3 Configuration

Now, all you need to do is inform ISPConfig of the new IP address so you can use it from the interface.

Go to the "System" > "Server IP Addresses" tab, then click on "New IP Address".

Enter the client and the IP address, and save.

You can now configure the services you want on this new IP address.