[bash] portscan.sh

portscan.sh

#!/bin/bash

PROGRAM_NAME=$(basename "$0")
VERSION_STR="1.0"

help_and_exit() {
  cat <<EOF
    Usage: $PROGRAM_NAME [OPTION]... HOST  PORT...

    -t TIMEOUT  If TIMEOUT seconds reached, consider the port is closed

    -h          display this help and exit
    -v          output version information and exit
EOF
  exit 0
}

version_and_exit() {
  echo "$PROGRAM_NAME version $VERSION_STR"
  exit 0
}

error() {
  local retval=$1  
  shift 
  echo "error: $*" 1>&2
  if [ $retval -ne 0 ]; then
    exit "$retval"
  fi 
}

timeout_value=1
while getopts "hvt:" opt; do
  case "$opt" in
    t)
     timeout_value=$OPTARG 
      ;;
    h)
      help_and_exit
      ;;
    v)
      version_and_exit
      ;;
    \?)
      error 1 "Try '-h' for help"
      ;;

esac
done

if [ "$#" -lt 2 ]; then
   error 1 "Try '-h' for help"
fi

shift $(($OPTIND - 1))
host=$1
shift

# 1-10 80 81 82
ports=""

for arg in "$@"; do
  if echo "$arg" | grep -- - >&/dev/null; then
    #range argument
    IFS="-" read begin end < <(echo "$arg")
    ports="$ports $(seq $begin $end)"
  else 
    ports="$ports $arg"
  fi
done

for port in $ports; do
  echo -n "trying $host:$port..."
 
  COMMAND=""
  case "$(uname -s)" in
    [Ll]inux*)
      COMMAND=`nc -z -w "$timeout_value" "$host" "$port"`
      ;;
    [Dd]arwin*)
      COMMAND=`read -t "$timeout_value" < <(nc -z -w 10 "$host" "$port")`
      ;;
  esac

  $COMMAND 
  retval=$?

  if [ $retval -eq 0 ]; then
    echo "ok"
  else
    echo "fail"
  fi
  
done