So I have a similar problem to this thread: Using SOCKS with Minecraft
Addison Crump's "another method" essentially helped me coming to the point where I am now.
I did the following:
I replaced my current JVM with this: -DsocksProxyHost=127.0.0.1 -DsocksProxyPort=3128 -DproxySet=true -Dhttp.nonProxyHosts="localhost|127.0.0.1"
start MC with that profile and then put: ssh (ssh file that automatically connects via a tunnel on port 80 with the username pi and logs me in on my Linux RaspberryPi) -L 25565:minecraftserverexample.net:25565
Now I add the server localhost:25565
And get the server... but when I try to join, I get the response: "Failed to login: Authentication servers are currently under maintenance" ... or sth like that.
Please help, I don´t know what's the problem.