Comment by malloc2x

Better to use, e.g.:

  ssh -fN -o ServerAliveInterval="240" -R 2222:localhost:22 example.com

(And on example.com ssh -p 2222 localhost)

This lets you easily keep the tunnel open long-term. Why?

  -f    Background the ssh process (don't need nohup)
  -N    Don't run any command
  -o... Make ssh do the work of keeping the session alive forever