If the system administrator deliberately filters out all traffic except port 22 (ssh), to a single server, it is very likely that you can still gain access other computers behind the firewall. This article shows how remote Linux and Windows users can gain access to firewalled samba, mail, and http servers. In essence, it shows how openSSH and Putty can be used as a VPN solution for your home or work place.
http://souptonuts.sourceforge.net/sshtips.htm
See the above link for the full article, which contains needed network diagrams.
Regards,
Mike Chirico
