Try opening the following ports: 1090, 4444, 4445. These are the ports I had to open on my Linux box to gain access to it from my Windows box.
I assume you have seen http://wiki.jboss.org/wiki/Wiki.jsp?page=UsingJBossBehindAFirewall, it at least lets you know what ports are in use by default.
Oops, typo! Port 1090 should be 1098.
Thus, these ports should all be open: 1098, 1099, 4444, 4445.
Thank you, I will try to open those ports on the gateway.
Further information: JBoss is running under Windows XP. Gateway is running under Linux.