sshjmp.sh

#!/bin/sh

while [ $# -gt 0 ]; do
   case $1 in
      -u|--user)
         SSH_USER=$2
         shift
         ;;
      -s|--ssh)
         SSH_ADDR=$2
         shift
         ;;
      -sp|--ssh-port)
         SSH_PORT=$2
         shift
         ;;
      -lp|--local-port)
         LOCAL_PORT=$2
         shift
         ;;
      -t|--target)
         TARGET_ADDR=$2
         shift
         ;;
      -tp|--target-port)
         TARGET_PORT=$2
         shift
         ;;
   esac
   shift
done

if [ -z "$SSH_ADDR" -o -z "$TARGET_ADDR" -o -z "$TARGET_PORT" ]; then
   echo "Usage: $0 [-u USER] [-lp LOCAL_PORT] -s SSH_ADDR [-sp SSH_PORT] -t TARGET_ADDR -tp TARGET_PORT"
   echo "    -u|--user USER                 Username for SSH"
   echo "    -s|--ssh SSH_ADDR              Address for SSH"
   echo "   -sp|--ssh-port SSH_PORT         Port for SSH (default 22)"
   echo "   -lp|--local-port LOCAL_PORT     Local port to listen (default TARGET_PORT)"
   echo "    -t|--target TARGET_ADDR        Address for proxy"
   echo "   -tp|--target-port TARGET_PORT   Port for proxy"
   exit 1
fi

PIPE_FILE=/tmp/jmp-pipe-$$
mkfifo $PIPE_FILE
nc -kl ${LOCAL_PORT:-$TARGET_PORT} < $PIPE_FILE | \
ssh -p ${SSH_PORT:-22} ${SSH_USER:-$USER}@$SSH_ADDR "nc $TARGET_ADDR $TARGET_PORT" > $PIPE_FILE