Alright, I'd like to make an interface for Peer-to-Peer connections online but I'm not sure exactly what language(s) to go about using.

My current issue is this: I have files I'd like to share on my server but I want them to be kept behind a VPN or Proxy. However, with the nature of both my host changes the IP constantly. The proxy changes very rapidly and the VPN IP changes on every connect/disconnect. Now, I know I could still host a server of some kind that updates with a DynamicDNS but I'd rather not. I would still have issues with port-forwarding through the VPN which is limited to a single port which I use for torrents anyway.

What I'd like to do is create a web front-end that had the user downloads, maybe a Java application that runs within the browser. At that point, they host the listening port for an incoming connection and it updates a queue of people waiting for file-downloads. My server will check that queue every few minutes and then connect to them and initiate the transfer.

Is something like this possible? If so, what language would I need for the front-end? I'm sure I can create the server portion from multiple languages that connect to a webpage and grabs the MySQL queue and connection info.