ssh-tunnel

#!/bin/bash

## The script is used for detecting the accessibility of tunnel from
##     remote-server:remote-port --> localhost:local-port
##     set USERNAME

## Status information will be displayed if -q argument is not specified.
## If -R is set, setup the tunnel automatically when it is shutdown.
## Use -r to set the remote port and -l to set the local port.

function howto {
  echo "usage: ssh-tunnel [-R,--restart  setup the tunnel if it is not online]"
  echo "                  [-q,--quiet  quiet mode]"
  echo "                  [-h,--help  show this help message]"
  echo "                  [-L,--local  local host address or ip, default 127.0.0.1]"
  echo "                  -H,--remote  remote host address or ip"
  echo "                  -r  remote port"
  echo "                  -l  local port"
}

function check_tunnel {
  ## localhost localport remotehost remoteport remoteuser
  r=$(ps -ef | grep "ssh -qTfNn -R $4:$1:$2 $5@$3" | grep -v grep -c)
  if [ "0" == "$r" ]; then
    echo -e "[offline] `date '+%Y-%m-%d %H:%M:%S'`    $3:$4 --> $1:$2"
  else
    echo -e "[ online] `date '+%Y-%m-%d %H:%M:%S'`    $3:$4 --> $1:$2"
  fi
}


local_host="127.0.0.1"
remote_host=""
quiet_mode=false
auto_restart=false
remote_port=-1
local_port=-1

while true; do
  case "$1" in
    -R | --restart ) auto_restart=true;;
    -q | --quiet ) quiet_mode=true;;
    -h | --help ) howto; exit -1;;
    -l )
       if [[ "$2" =~ ^[1-9][0-9]*$ ]]; then
           local_port="$2"
       else
           echo "invalid local port: $2"
           howto;exit 1
       fi
       shift
       ;;
    -r )
       if [[ "$2" =~ ^[1-9][0-9]*$ ]]; then
           remote_port="$2"
       else
           echo "invalid remote port: $2"
           howto;exit 1
       fi
       shift
       ;;
    -H | --remote )
       if [[ "$2" =~ ^((25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9][0-9]|[0-9])\.){3}(25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9][0-9]|[0-9])|[a-z0-9]+([\-\.][a-z0-9]+)*\.[a-z]{2,6}$ ]]; then
           remote_host="$2"
       else
           echo "invalid remote host address: $2"
           howto;exit 1
       fi
       shift
       ;;
    -L | --local )
       if [ "localhost" == "$2" -o "127.0.0.1" == "$2" ]; then
           local_host="$2"
       else
           echo "local address must be one of [localhost, 127.0.0.1], but got: $2"
           howto;exit 1
       fi
       shift
       ;;
    * )
       if [ -z "$1" ]; then break; else echo "unknown argument: $1"; fi
       howto; exit 1
       ;;
  esac
  shift
done

if [ "-1" == "$remote_port" ]; then
  echo "-r is missing, remote port is required"
  howto;exit 1
fi

if [ "-1" == "$local_port" ]; then
  echo "-l is missing, local port is required"
  howto;exit 1
fi

if [ -z "$remote_host" ]; then
  echo "-H,--remote is missing, remote host address is required"
  howto;exit 1
fi


rcode=$(check_tunnel "$local_host" "$local_port" "$remote_host" "$remote_port" "hejun")
if [ "0" != "$(echo $rcode | grep "offline" | grep -v grep -c)" ]; then
  echo $rcode
  if [ "true" == "$auto_restart" ]; then
      OLD_LD_LIBRARY_PATH="$LD_LIBRARY_PATH"
      LD_LIBRARY_PATH=""
      ssh -qTfNn -R $remote_port:$local_host:$local_port USERNAME@$remote_host
      LD_LIBRARY_PATH="$OLD_LD_LIBRARY_PATH"
      if [ "0" != "$(check_tunnel "$local_host" "$local_port" "$remote_host" "$remote_port" "hejun" | grep "offline" | grep -v grep -c)" ]; then
          echo -e "[ failed] `date '+%Y-%m-%d %H:%M:%S'`    rebuild tunnel $remote_host:$remote_port --> $local_host:$local_port"
      else
          echo -e "[   OK  ] `date '+%Y-%m-%d %H:%M:%S'`    rebuild tunnel $remote_host:$remote_port --> $local_host:$local_port"
      fi
  fi
else
  if [ "true" != "$quiet_mode" ]; then
    echo $rcode
  fi
fi