I have a gateway system, which hides 3 other computers from the outside world. I wish to setup a FTP server such that when I access the FTP server on the gateway, I reach one of the inner hidden systems, i.e., if I ftp to 18.104.22.168, I automatically see the 192.168.1.2 ftp directory, where 192.168.1.2 is the local system. Also, can this be done for HTTP servers also? I get to see the web directory of the inner system?
This can be done using Shorewall. There's a tutorial at the web-site.