#!/usr/bin/perl  -w

# This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License.
# http://herselfswebtools.com
# Linda MacPhee-Cobb"
# modified by Chris Jones, cj@cr-jay.ca, Dec. 2002

# a tool to get non static ip address when
#you have a router installed, this also works if you do not
#have a router.

#works on windows, linux, unix
# Windows: use the scheduler to check periodically
# linux/unix: use cron to check periodically

#compares today's IP with previous.  Sends an email if the IP has changed.

use strict;
use Net::SMTP;
use LWP::Simple;

##***********************************
#you need to edit the following:
my $smtphost = "your-smtp-host.com";
my $from = "me\@mypop.com";
my $to = "somone\@theirpop.com";
#********************************

         #get page with ip info
         my $html = get( 'http://checkip.dyndns.org' );
         #print $html;

         #parse the IP address from the reply
         # note, does not check for valid IP just that the construct is there
         $html =~ /(\d+)\.(\d+)\.(\d+)\.(\d+)/;

         my $a = "$1";
         my $b = "$2";
         my $c = "$3";
         my $d = "$4";
         my $ip = "$a.$b.$c.$d";
         my $ipfile    = 'ip.dat';
         my $prev_ip = "";
         if( open S, "$ipfile" )
         {
                 $prev_ip = <S>;
                 close S;
         }

         if (!($ip eq $prev_ip))
         {
                 my $smtp = Net::SMTP->new("$smtphost");
                 # First the envelope bits
                 $smtp->mail("$from");
                 $smtp->to("$to");

                 # Now for the message itself
                 $smtp->data();
                 $smtp->datasend("From: $to\n");
                 $smtp->datasend("To: $from\n");
                 $smtp->datasend("Subject: IP \n");
                 $smtp->datasend("\n");
                 $smtp->datasend("IP Changed: was $prev_ip, now: $ip\n");
                 $smtp->dataend();
                 $smtp->quit;

         }
         #store the IP address for next comparison
         open S, ">$ipfile";
         print S $ip;
         close S;