Using SSH/telnet w/ cable modem & router

I’m running Redhat 9.0 on an older computer, and I use a router to log onto the internet with an Jaguar Mac, a Win2000 box, and a Win XP box. The linux box accesses the internet fine, but when I try to run an SSH or telnet server, I can only connect through the linux box; not even the other computers on the router will read it. A DNS will not run on it. How can I configure the router (Linksys 4-port router) and the Redhat computer to run these servers accessible to computers on the network and accessible to computers outside of the network (such as at work or school).

Thanks for your help.

John