Port Knocking SSH wrapper

kssh

#!/bin/bash

# Author: Michael Best <mbest@arcticlinux.com>

# Designed to work with the Shorewall Port Knocking Implementation
# http://shorewall.net/PortKnocking.html

COMMAND="ssh"
PORT=1600
TIMEOUT=2

function USAGE {
  echo -e "Usage for $0\n"
  echo -e "By default this program knocks port 1600 with tcping, and then calls ssh"
  echo -e "Example: kssh username@example.com\n "
  echo "Options:"
  echo "-c  Sets the default ssh command, default ssh (ssh, mosh, etc)"
  echo "-p  Sets the port knocking port, default 1600"
  echo "-t  Sets the timeout value on tcping, default 2"
  echo "-h  Displays usage"
  exit 1
}

while getopts :c:p:t:h OPT; do
  case $OPT in
    c) # set ssh command
      COMMAND=$OPTARG
      ;;
    p) # set knocking port
      PORT=$OPTARG
      ;;
    t) # set timeout
      TIMEOUT=$OPTARG
      ;;
    h)  #show usage
      USAGE
      ;;
    \?)
      echo -e "\nInvalid Option -$OPTARG\n"
      USAGE
      ;;
  esac
done

shift $((OPTIND-1))

HOST=`echo $1 | sed 's#.*@##'`

echo "knocking $HOST $PORT, $COMMAND $*"

tcping -q -t $TIMEOUT $HOST $PORT &> /dev/null

$COMMAND $*