The networks at the schools are often extremely limited for obvious reasons. One school district blocks everything but HTTP, and is even blocking SSH tunneling over HTTP (using Apache's mod_proxy / HTTP connect method). FTP is shut down. STFP is shut down. Sites with the word "proxy" are blocked. I've read a few posts in this forum about IT blocking "bittorrent-like" traffic, and requiring ports to be opened. I'm pretty certain that UPnP is not going to work given the strength of the IT in the schools. I see the option for adding known hosts in the folder settings, which lets me specify a host and port which would let me connect to port 80, and I'm going to test this out next time I get to the schools. But most inbound traffic is blocked. We had this problem when we tried using FTP, since it assigns random ports for data transfer. SFTP worked on one site through a tunnel (again, the sites are not consistent and IT doesn't always have the time to accomodate our needs). I know that any return traffic trying to connect to the laptops on site will need to have the router forward an external port to the port I specify in the settings. But we won't be able to get IT to do that. I couldn't find information on the Bittorrent Sync relay anywhere. More information on this will help me know whether it will work and what to talk to with the IT departments in the districts. To get a common working solution for my problem for all the sites, I'll likely need sync option that communicates over HTTP exclusively, which means I'm probably stuck with WebDAV or Dropbox (which uses a RESTful web service API for transfers). I'd much prefer the Bittorrent Sync route because it reduces external bandwidth (our media files are pretty extensive) and is a great common solution for live mirroring back home on our servers with the collected data as well, and the files are not stored in the cloud (since they may contain sensitive student information). So to focus my question, how does the relay work? /cm p.s. If the name had given me a clue to answer my question, I would have answered the question myself. I do a great amount of research before posting questions on forums (here, stackoverflow, etc.), and only do so after an extended period of experimentation and effort. I've read a few of your posts on the wishlist, and many of them come across as condescending and arrogant, and this response is no exception. I appreciate any information you can supply in helping in my scenario, but please drop the assumptive belittling tone or don't reply at all.