Forwarding all traffic for a private IP to another private IP (Fortigate)

[AJnet]

I'm migrating a voip phone system to its own (virtual) interface and subnet on a fortigate firewall.

The idea was to first configure each phone to point to what will be the PBX's new IP address (172.17.200.2). Since the current config on all the phones use the old PBX IP, the PBX's IP address (172.17.2.254) will be the last thing to change (after all the phones have been reconfigured).

So, since there won't be an actual device at 172.17.200.2 during the transition, I'm trying to figure out a way to forward traffic sent to the new IP (172.17.200.2) and forward it to the old IP (172.17.2.254).

What would be the best approach? Just a firewall rule with the old IP as the source and the new IP as the destination, enable nat, and enable preserve source port? Or is there a different approach I should use?

I'm running firmware 7.2.6.

Thanks :)

[AEK · Accepted solution]

You can do this in two different ways.

• Add secondary interface to your PBX with the new IP
• Or use Virtual IP at firewall level to forward all traffic of the new IP to the old IP

If you want the second solution the below link will help.

https://community.fortinet.com/t5/FortiGate/Technical-Tip-Virtual-IP-VIP-port-forwarding-configurati...

[AJnet]

Ah-ha, my PBX does have the ability to create virtual interfaces--that will certainly make things a whole lot easier. Thanks for the two suggestions :)