Debian startup file for SSH port forwaring (connecting to Raspberry Pi behing NAT)

rssh.md

Run update-rc.d rssh defaults after adding this file to /etc/init.d on your Raspberry.

To SSH through NAT you should use "proxy" server (TARGET in this script) with GatewayPorts yes in its /etc/ssh/sshd_config.

After configuring middle server just run ssh pi@example.com -p 2242 to connect to your Raspberry behind the NAT.

rssh.sh

#!/bin/sh

# /etc/init.d/rssh

KEY="/home/username/.ssh/id_rsa"
PORT="2242"
TARGET="server_username@example.copm"
PIDFILE="/var/run/rssh.pid"

case "$1" in
  start)
    echo "Starting script rssh"
    /usr/bin/ssh -i $KEY -R $PORT:localhost:22 $TARGET sleep 999999999 &
    echo "$!" > $PIDFILE
    ;;
  stop)
    echo "Stopping script rssh"
    PID=`cat $PIDFILE`
    kill PID
    ;;
  *)
    echo "Usage: /etc/init.d/rssh {start|stop}"
    exit 1
    ;;
esac

exit 0