Joining a mariusnet game via TCP/IP

[Zaknafein]

So I was wondering if it is possible, when a person hosts a game on mariusnet, for a player to put in the hosts IP address into TCP/IP and join the game that way?

I tried it and myth said there was a firewall error, but the host is able to have people join via mariusnet.

[Pyro]

I think it used to be possible but was dealt with at some point so it could not be exploited.