[arch-general] tunneling help needed (ssh?)

Hi there, I know this isn't very arch specific but I lack ideas on where else to ask. Problem: A server situated in a network that can't be reached from the outside, all ports are blocked. I want to give specific outside users simple ftp access to a directory on this server (password protected). I'm in control of the server inside the network. I'm in control of another server inside this network that can be reached (at least port 80) but I'd like to avoid using this server. I may have some control over outside servers. So, what can I do?