#!/bin/bash


basename=`basename $0`

sleepTime=300

defSshTunPort=22


function usage {
   cat <<USAGE
$basename - Create and keep open an ssh tunnel

usage:
   $basename [OPTIONS]

options:
   -p, --ssh-port PORT     SSH Port from this system to the other for 
                           setting up this tunnel. Default: $defSshTunPort
   -u, --user USER         User on remote system. Default: \$USER
   -H, --host HOST         Remote system IP or hostname
   -r, --remote-port PORT  Port for using tunnel on remote system
   -l, --local-port PORT   Port for using tunnel on this (the local) 
                           system
   -h, --help              This help information

For this to really be useful you need passwordless ssh between the users 
on these two systems. You need to set that up yourself and of course be 
mindful of the security issues involved.

2008-03-21  Dino Morelli <dino@ui3.info>

USAGE

   exit 1
}


# arg parsing

getoptResults=`getopt -o p:u:H:r:l:h --long user:,host:,remote-port:,local-port:,help -n $basename -- "$@"`

if [ $? != 0 ] ; then usage ; fi

# Note the quotes around `$TEMP': they are essential!
eval set -- "$getoptResults"

while true ; do
	case "$1" in
      -p|--ssh-port) optSshPort="$2" ; shift 2 ;;
      -u|--user) optUser="$2" ; shift 2 ;;
      -H|--host) optHost="$2" ; shift 2 ;;
      -r|--remote-port) optRemotePort="$2" ; shift 2 ;;
      -l|--local-port) optLocalPort="$2" ; shift 2 ;;
      -h|--help) optHelp=1 ; shift ;;
		--) shift ; break ;;
		*) echo "Internal error!" ; exit 1 ;;
	esac
done

echo "[$optHost]"


# validate the args

if [ "$optHelp" = 1 ]; then usage ; fi

if [ -z "$optHost" ]
then
   echo "Remote host required!"
   echo
   usage
fi

if [ "$optRemotePort" = "" ]
then
   echo "Remote port required!"
   echo
   usage
fi

if [ "$optLocalPort" = "" ]
then
   echo "Local port required!"
   echo
   usage
fi


optUser=${optUser:-$USER}
optSshPort=${optSshPort:-$defSshTunPort}

command="ssh -p $optSshPort -N -R $optRemotePort:localhost:$optLocalPort $optUser@$optHost"

# This will keep trying to restore the tunnel any time it's down
while true
do
   echo -n `date`
   echo "  Starting tunnel with this command:"
   echo "  $command"
   echo "Press ctrl-c twice to REALLY stop"
   $command
   echo "Stopped at $(date)  Restarting in $sleepTime secs"
   sleep $sleepTime
   echo "Restarting.."
done