#!/bin/bash
# yet another port scanner
# by shudder <shudder@gbg.bg>
# dedicated to a very special girl

_exit() {
  rm -f ~/.$name.ports
}
trap _exit 0
name="`basename $0`"
hname="`basename $0 | tr a-z A-Z`"
fname="$0"

usage() {
  case $1 in
    -*) echo "invalid option: $1";;
  esac

  echo "usage:   $name [-i|-c|-a] <address> <start port> <end port>"
  echo "           -i	interactive mode"
  echo "           -c	check if address is up"
  echo "           -a	about $name"
  exit 1
}

help() {
  echo "scan		begin scanning"
  echo "save		save port information to file"
  echo "check		check if address is up"
  echo "clear		clear screen"
  echo "help		get help"
  echo "about		about this program"
  echo "quit		exit the program"
}

about() {
  echo "        __________________________________"
  echo "       (${hname}__yet_another_port_scanner_**_)"
  echo
  echo "      ____________               ____________ "
  echo "    _(_greetings__)________     (_by shudder_)_____ "
  echo "   (_jeux,_ZeaN,_ultrafina_)      (_shudder@gbg.bg_) "
  echo "         (_sonne,_Elessar_)"
  echo
}

[ ! "$1" ] && usage

if [ "$1" = "-i" ]; then
  prompt="$name"
  echo "Interactive mode.Type help for help"
  while true; do
    read -p "$prompt> " line
    if [ "$line" ]; then
      set $line
    else
      continue
    fi
    command="`echo $1 | tr A-Z a-z`"
    case $command in
     help)
       help;;
     scan)
       if [ ! "$address" ] || [ ! "$sport" ] || [ ! "$eport" ] || [ "$2" = "-n" ]; then
         echo "writing database.use option -n next time to provide new information"
         read -p "address: " address
         read -p "start port: " sport
         read -p "end port: " eport
       fi

       if [ "$address" ] && [ "$sport" ] && [ "$eport" ]; then
         $0 $address $sport $eport
         prompt="$address"
         save="yes"
       else
         echo "cannot scan" 
         echo "address: $address" 
         echo "start port: $sport"
         echo "end port: $eport"
         prompt="$name"
       fi;;
     save)
       if [ "$save" = "yes" ]; then
         read -p "filename: " filename
         [ "$filename" ] && cp ~/.$name.ports $filename || echo "no filename given"
       else
         echo "nothing to save"
       fi;;
     check)
       read -p "address: " adr
       $fname -c $adr;;
     clear)
       echo -n "";;
     about)
       about;;
     quit)
       exit 0;;
     *)
      echo "$1: Unknown command."
    esac
  done
fi

if [ "$1" = "-c" ]; then
  if [ ! "$2" ]; then
    echo "$name: No address given"
    exit 1
  fi

  # This may stall for a while.You could send INT to stop it.
  if ping -c 1 $2 &> /dev/null ; then
    echo "$2 is up!"
    exit 0
  else
    echo "$2 is down."
    exit 1
  fi
fi

if [ "$1" = "-a" ]; then
  about
  exit 0
fi

if [ "$2" ] && [ "$3" ]; then
  host="$1"          # Hostname
  start="$2"         # Port from where to start
  stop="$[$3+1]"     # End port
  range1="$2"
  range2="$3"

  if ! (which nc &> /dev/null) ; then
    echo "$name: netcat was not found.$name can't continue"
    exit 1
  fi

  # Our ports are numerical, aren't they?!
  if [ "$[$range1]" = "0" ] || [ "$[$range2]" = "0" ]; then
    echo "invalid ports!"
    exit 172
  fi

  echo "Scanning $host for open ports"
  rm -f ~/.$name.ports
 
  # Checking if hostname is reachable
  if ! (ping -c 1 $host &> /dev/null) ; then
    echo "$name: can't connect to $host"
    exit 1
  fi
  logger -i "Scanning $host for open ports"
  echo "SERVICE		PORT" >> ~/.$name.ports
  while [ "$start" -lt "$stop" ]; do
    if nc -z $host $start ; then

      # I grep twice because the service name might be tabulated from the port
      # So just to make sure I'm doing 'em both
      pname1="`grep \" ${start}/tcp\" /etc/services`"
      pname2="`grep \"	${start}/tcp\" /etc/services`"
      if [ "$pname1" ] || [ "$pname2" ]; then
        [ "$pname1" ] && set $pname1
        [ "$pname2" ] && set $pname2
        echo "$1		$2" >> ~/.$name.ports
        pcount="$[$pcount+1]"
      else

        # We don't know what kinda service lays here.So we print - unknown
        echo "unknown		$start/tcp" >> ~/.$name.ports
        pcount="$[$pcount+1]"
      fi
    fi

    # Increase the port by one then start all over again
    start="$[$start+1]"
  done
  if [ ! "$pcount" ]; then
    echo "There are no open ports in this range"
    exit 0
  fi

  # Check what to write in the summary.
  if [ "$pcount" -gt "1" ]; then
    str1="are"
    str2="s"
  else
    str1="is"
  fi

  # Summary
  echo "There $str1 $pcount open port$str2 on $host \
in the range of $range1-$range2" >> ~/.$name.ports
  cat ~/.$name.ports
else
  usage $1
fi