Does Steam work through Tor or a VPN?

I talked to Steam Support about Steam Offline. I have been told:

You can set up your Steam account to run in offline mode prior to connecting to your school's network […] you must allow Steam to complete necessary updates in order to enable Offline mode (you must establish a temporary connection to the internet for this reason).

So, I can't go offline while offline. I must remember to go offline while online, or I'm gently caressed. I don't always have this luxury, however.

I've tried using my mobile's internet connection for this purpose. However, much to my surprise, Steam now fails to connect through that as well. Why, thank you so much, Wind.

I'm thus left with two possibilities to enable offline mode while offline:

• A VPN, or
• The Tor network.

Does Steam work through either them? I just need it to connect to the network for long enough to realize that there are no updates, after all, and that it's okay to let me play my games.

A VPN takes over the entire OS' connection. It is program-independent. As such, a VPN will work.

Tor is more doubtful, because I don't think Steam supports a SOCKS proxy out of the box. There are programs out there that force a certain program to go through a SOCKS proxy though (which I couldn't find on a quick Google. I'll have a look around).

I would think Tor would have much much much too high latency, if it routed the traffic at all.

VPNs are usually paired with firewalls, and firewalls, if configured correctly, will only allow traffic on specific, whitelisted, ports.

Steam uses a lot of unusual ports:

Steam Client

    UDP 27000 to 27015 inclusive (Game client traffic)
    UDP 27015 to 27030 inclusive (Typically Matchmaking and HLTV)
    TCP 27014 to 27050 inclusive (Steam downloads)
    UDP 4380

Dedicated or Listen Servers

    TCP 27015 (SRCDS Rcon port)

Steamworks P2P Networking and Steam Voice Chat

    UDP 3478 (Outbound)
    UDP 4379 (Outbound)
    UDP 4380 (Outbound)

If your VPN restricts ports higher than 1024, you're out of luck. Some (older) admins will allow traffic on 1024+ since most important network services run on ports lower than 1024, but its common to block EVERYTHING, and only allow very specific traffic to cut down on the ability of trojans and such, to communicate.

My experience with Steam is, once you've connected one time, the client will try to connect, then default to offline if it fails.