There are times you want to access your ssh server somewhere stuck behind a firewall. SSHHub is a solution for that. Think of ssh-teamviewer - but so much more lightweight. Its free and after a one-time registration its literally one command on your server. Run on your server:

while true; do ssh [username]@sshhub.de -R 22:localhost:22 -N -o ServerAliveInterval=10; done

while on any other computer you run

ssh -J [username]@sshhub.de localhost

and there you are connected! One-time registration is just as simple:

ssh info@sshhub.de register