Every application you use on for the internet has some port associated with it, some of the more common ports are :
HTTP: - 80 (Browser)
FTP: - 21 (and Audio Galaxy)
NNTP: 119
Telnet: - 23
SMTP: - 25 (Mail)
Gopher: - 70
POP 3: - 110 (Mail)
IRC: - 6667
While it is true that you are opening another virtual door to your PC it would have to intereact with something using port 6346 on your computer to make it dangerous. It is really no more dangerous that any other port you have opened... the main point is, I think, to limit the ports you have open to those that need to be open.