I have my primary linux box, on my office LAN. I have my domain, fyrenice.com pointed at my linux box, port forwarded so I can remotely access it from home, etc.

I have installed Zimbra on another linux box on this same LAN...the installation goes fine, except when it probes available ports. At that point it fails for all ports, as those ports are currently either not forwarded or are forwarded to my primary linux box.

I receive all my office email on my primary box here, and do all work from this machine. I had hoped to set up and fiddle with Zimbra on this other box, to make sure it's working and then to migrate my email, web and such over to it.

How should I proceed, without causing downtime in the interim between forwarding all required ports to the zimbra box, and being up and running?