A set of scripts to enable remote SSH tunnelling on a device. Originally written for a Raspberry Pi, so that when installed in a remote location inside a network it can easily be accessed for maintenance.

create-tunnel.sh

#!/bin/bash

# This sits on the device you want to be able to tunnel back into
# Replace USER and SERVER lines with your tunnel user (if different from local) and domain or IP

createTunnel() {
  /usr/bin/ssh -N -R 2222:localhost:22 USER@SERVER
  if [[ $? -eq 0 ]]; then
    echo Tunnel created successfully
  else
    echo An error occurred creating a tunnel. RC was $?
  fi
}
/bin/pidof ssh
if [[ $? -ne 0 ]]; then
  echo Creating new tunnel connection
  createTunnel
fi

crontab

# To go into the crontab of the device

*/1 * * * * /path/to/script/create-tunnel.sh >> /path/to/script/create-tunnel.log 2>&1

remote-ssh.sh

#!/bin/bash

# Assuming ports remain unchanged, run this on your tunnel server to connect back in to your device.
# To test the connection run `sudo lsof -i -n | egrep '\<sshd\>'` taken from http://superuser.com/a/248391/85813

user=$1
ssh -l $user -p 2222 localhost