I want to put a pfSense router in front of my Untangle UTM. There is only one thing I am not too sure about.
If the Untangle box will sit behind another router and run OpenVPN, all I need to do to route traffic to the Untangle through the pfSense is add a static route on the pfSense box and open the port used by OpenVPN right?
Right now the Untangle box is the router.
In most cases, not even a route. A port map/forward entry on the pfSense to the Untangle should be all that is needed.
Why not use Openvpn server in pfsense ?
A static route on in the Pfsense for the OpenVPN address pool pointing to you Untangle server will be needed or to activate the "Route VPN traffic that would go through the Bridge".
Just port forwarding will just allow the tunnel to be established but if clients/servers on the other side have Pfsense as there GW they will need the route back. (or Packet filter rule).