Autossh init script(Ubuntu) for reverse ssh tunneling

_etc_init.d_autosshd

#! /bin/sh
### BEGIN INIT INFO
# Provides:          autosshd
# Required-Start:    $remote_fs $syslog
# Required-Stop:     $remote_fs $syslog
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Short-Description: autosshd initscript
# Description:       This file should be used to construct scripts to be
#                    placed in /etc/init.d.
### END INIT INFO

#
# autosshd This script starts and stops the autossh daemon
#
# chkconfig: 2345 95 15
# processname: autosshd
# description: autosshd is the autossh daemon.

# Load the VERBOSE setting and other rcS variables
. /lib/init/vars.sh

# Define LSB log_* functions.
# Depend on lsb-base (>= 3.2-14) to ensure that this file is present
# and status_of_proc is working.
. /lib/lsb/init-functions

# Check that networking is up.
#[ ${NETWORKING} = "no" ] && exit 0

PATH=/sbin:/usr/sbin:/bin:/usr/bin
NAME=autossh
DAEMON=/usr/bin/$NAME
TUNNEL_HOST="your public ssh server"
TUNNEL_PORT=90022
DAEMON_ARGS=" -M 0 -f -nNT -i PATH_TO_YOUR/id_rsa -R $TUNNEL_PORT:localhost:22 $TUNNEL_HOST"
DESC="autossh for reverse ssh"
PIDFILE=/var/run/$NAME.pid
export AUTOSSH_PIDFILE=$PIDFILE
SCRIPTNAME=/etc/init.d/$NAME

#
# Function that starts the daemon/service
#
do_start()
{
	# Return
	#   0 if daemon has been started
	#   1 if daemon was already running
	#   2 if daemon could not be started
	start-stop-daemon --start --quiet --exec $DAEMON --test > /dev/null \
		|| return 1
	start-stop-daemon --start --quiet --exec $DAEMON -- \
		$DAEMON_ARGS \
		|| return 2
	# Add code here, if necessary, that waits for the process to be ready
	# to handle requests from services started subsequently which depend
	# on this one.  As a last resort, sleep for some time.
}

#
# Function that stops the daemon/service
#
do_stop()
{
	# Return
	#   0 if daemon has been stopped
	#   1 if daemon was already stopped
	#   2 if daemon could not be stopped
	#   other if a failure occurred
	start-stop-daemon --stop --quiet --retry=TERM/30/KILL/5 --pidfile $PIDFILE --name $NAME
	RETVAL="$?"
	[ "$RETVAL" = 2 ] && return 2
	# Wait for children to finish too if this is a daemon that forks
	# and if the daemon is only ever run from this initscript.
	# If the above conditions are not satisfied then add some other code
	# that waits for the process to drop all resources that could be
	# needed by services started subsequently.  A last resort is to
	# sleep for some time.
	start-stop-daemon --stop --quiet --oknodo --retry=0/30/KILL/5 --exec $DAEMON
	[ "$?" = 2 ] && return 2
	# Many daemons don't delete their pidfiles when they exit.
	rm -f $PIDFILE
	return "$RETVAL"
}


#
# Function that sends a SIGHUP to the daemon/service
#
case "$1" in
  start)
	[ "$VERBOSE" != no ] && log_daemon_msg "Starting $DESC" "$NAME"
	do_start
	case "$?" in
		0|1) [ "$VERBOSE" != no ] && log_end_msg 0 ;;
		2) [ "$VERBOSE" != no ] && log_end_msg 1 ;;
	esac
	;;
  stop)
	[ "$VERBOSE" != no ] && log_daemon_msg "Stopping $DESC" "$NAME"
	do_stop
	case "$?" in
		0|1) [ "$VERBOSE" != no ] && log_end_msg 0 ;;
		2) [ "$VERBOSE" != no ] && log_end_msg 1 ;;
	esac
	;;
  status)
	status_of_proc "$DAEMON" "$NAME" && exit 0 || exit $?
	;;
  *)
	echo "Usage: $SCRIPTNAME {start|stop|status|restart}" >&2
	exit 3
	;;
esac

:

ssh_config

Host remote_name
    HostName 127.0.0.1 # or use your any hostname wrote to /etc/hosts in public ssh server
    ProxyCommand ssh your_public_ssh_server nc localhost 90022

For some people experiencing this kindof errors:

• Too many authentication failures (you have a lot of keys into your ~/.ssh, without a complete ~/.ssh/config)
• The server unknown in your ~/.ssh/known_hosts

Add more options to your ssh command: -o IdentitiesOnly=yes -o StrictHostKeyChecking=no
This is especially true when it does not work as root, but sudo.

Also note that:

• you do not use the autossh monitoring in this example. With monitoring enabled the stop command will not kill the "ssh" process
• you should rather use the binary and not the wrapper of autossh : DAEMON=/usr/lib/autossh/autossh

Interesting source about PID file management with autossh: http://stackoverflow.com/questions/34094792/autossh-pid-is-not-equal-to-the-one-in-pidfile-when-using-start-stop-daemon

Here is my own gist, based on yours: https://gist.github.com/Clement-TS/48ae8d23f6452cd1a3a071640c1bd07b