First off, do you have a router, a hardware router in order to get your internet? If so, there should be some sort of software interface (either a utility of some sort, or an interface via a browser) that will allow you to open (enable a pass-through and forward) port 6346.

Also, if you have Mas OS X, you will have to disable the personal firewall which can be found under sharing of the system preferences.

If you have any other form of software fierwall, that too, will have to be disabled.