Re: how do I unblock an external port?
If the firewall on the server is allowing all connections, and the firewall on the client is allowing all connections, then there's no firewall problem. You don't "open a port", you simply run a program that transmits or receives on that port and make sure your firewalls aren't blocking the port.
Firestarter (please, people; stop using it!), UFW and pretty much every other "firewall" program out there on Linux will just configure the internal netfilter/IPtables firewall. If you change the settings on one "firewall" you change it for all.
I try to treat the cause, not the symptom. I avoid the terminal in instructions, unless it's easier or necessary. My instructions will work within the Ubuntu system, instead of breaking or subverting it. Those are the three guarantees to the helpee.