had exactly this feature. They provided ssh access via port 80.
- different port (443, not 80)
- different protocol used on that port (https, not ssh)
In the old days, only the port number mattered. Today, DPI means the protocol matters as well.
Edit: I tested that time ago:
https://news.ycombinator.com/item?id=38753897
And to save roundtrips: I believe it must be possible to analyze encrypted traffic to find out which protocol is used. But I doubt that the hospital admins are so motivated or sophisticated.
An SSH server and client do not use SSL/TLS to set up the connection. They use the SSH protocol.
As soon as you connect to an SSH server, the server sends an identification string. The identification string always starts with:
SSH-
In the old days, corporate firewall rules were based solely on port numbers. So you could connect to an outside SSH server running on port 80, even if port 22 was blocked. Nowadays, an SSH server running on any port (80, 443, or any other) can easily be detected and blocked.
I ask because if it works, the principle is the same: using a commonly used protocol to circumvent limitations. It used to be easier to do then, it's more involved now.
In other words: is it possible to tunnel anything through https?
No it's not. The earlier method used only a commonly used port, and did not require the use of a commonly used protocol.
Sort of a redo of the pirate radio ethos of the 60s.
https://www.shodan.io/search/facet?query=ssh&facet=port https://www.shodan.io/search/facet.png?query=ssh&facet=port
Port 80 is a lot less common though.