Script for IP Change Alert

If you need to be notified upon the IP address of the system it can be achieved through following Perl Script
At first a sendemail needs to be installed using : sudo apt-get install sendmail (in Debian based Distros)
Else you may use another MTAs too like sendmail or postfix that is available.
#!/usr/bin/perl -w
#Anwesh Tiwari Oct 12 2011

use strict;
my $today=`date +%Y-%m-%d" "%r`;
#location of TEMP file
my $ip_last_check_file = "/home/tmp/IP-Address";
my $ip_now = `curl -s http://checkip.dyndns.org`;
$ip_now =~ s/.*?(\d+\.\d+\.\d+\.\d+).*/$1/s;

open(IP, "<$ip_last_check_file") or die "Cannot open $ip_last_check_file: $!";
my $ip_last_check = <IP>;0
close(IP);

if ($ip_now ne $ip_last_check)
{
  open(IP, ">$ip_last_check_file") or die "Cannot open $ip_last_check: $!";
  print IP $ip_now;
  close(IP);
#-s "SMTP address of your SMTP server instead" of "-s localhost" if you dont have ipaddress running.
  my $output = `sendemail -f sentname\@yourdomain.com -t alertaddress\@yourdomain.com -s localhost -u IP-CHANGE-ALERT -m Gateway IP-address has changed to $ip_now.\\\\n Event Time :$today`;
}

exit;