Hi Giftsamuel,
I'm confused by your two questions. In the first you said "My clients and servers will have a firewall between them" and in the second you said "Both the client and server is behind the firewall". If there is no firewall between the client and the server, then there shouldn't be a problem. If there is a firewall between the client and the server, and if the firewall translates the server's 'external" address to an "internal" address, then you can use the "serverBindAddress" parameter to bind the server to the "internal" address and the "clientConnectAddress" parameter to give the client the "external" address. See Chapter 5 of the Remoting Guide (http://www.jboss.org/jbossremoting/documentation/v2.html) for more information.
-Ron