#!/bin/bash

 #Performs port scan using nmap

 print_usage() {

 cat << _EOF_

         Utility to scan open ports. Can be used to scan ports for a domain or a list of domains specified in a file.

         Example Usage:

                 -h, --help              Show brief help

                 -d, --domain            Domain name or ip to scan

                 -f, --file              Spefify a file containing domains/IPs to scan

 _EOF_

 }

 scan_port() {

         domain=$1

         echo "Scanning ports for $1...."

         nmap -sT -T4 $domain | sed '/^\(Nmap scan\|PORT\|[0-9]\)/!d' | tee -a $port_scan_result_file

 }

 create_port_scan_result_file() {

         port_scan_result_file="/tmp/port-scan-`date "+%Y-%m-%d-%H:%M:%S"`.txt"

 	touch $port_scan_result_file

 }

 while getopts "f:d:" opt; do

         case "$opt" in

                 d) domain=$OPTARG    ;;

                 f) file=$OPTARG      ;;

                 *) print_usage; exit 1 ;;

         esac

 done

 if [ ! -n "$domain" ] && [ ! -f "$file" ]; then

         echo "Option -d $domain or -f $file missing or designates to wrong entry" >&2

         exit 1

 fi

 scan_port_flow() {

 if [ -n "$domain" ]; then

 	create_port_scan_result_file

 	scan_port $domain

 	echo "Scan result:$port_scan_result_file"

 fi

 if [ -n "$file" ]; then

 	create_port_scan_result_file

 	for domain in $(cat $file)

 	do

 		scan_port $domain

 	done

 	echo "Scan result: $port_scan_result_file"

 fi

 }

 scan_port_flow