How to make the Fedora's X Server listen on the network? I also have the same problem, and the solution using SSH will not work, since most of my client's system are older *nix which does not have SSHD installed as a standard package.
Which older versions of Unix? OpenSSH is available for many popular Unicies; I use it HP-UX and Solaris at work.
See also http://www.bastille-linux.org/jay/stupid-protocols.html if you're thinking of using telnet, ftp, rlogin, rsh, rcp etc.
Paul.