#!/usr/bin/perl
use warnings;
use strict;

# Declarations of scalars and such
my ($oldIPAddress, $currentIPAddress);
my $logFilename = 'iplog_perl';

# change directory to root or inform user of his none-rootness
chdir '/root/logs/' or die "Are you root, dude?: $!", "\n";

# open the IP log file to read last IP from it
open my $IPLOG, '<', $logFilename;

# read from IPLOG handle and get the last IP address saved 
while ( <$IPLOG> ) {
	$oldIPAddress = $_;
        chomp $oldIPAddress;

	print "The old IP address was: $oldIPAddress", "\n";
}
# close filehandle
close $IPLOG;

# calls 'ifconfig' and stores output in $output	
my $output = `ifconfig`;

# $output operations
my @lines = split /\n/, $output;

# goes through @lines until $line matches the regex
for my $line ( @lines ) {
	if ( $line =~ /\s+inet addr:(.*).P-t-P/ ) {
                 $currentIPAddress = $1;

                 if ( not defined $currentIPAddress ) {
			die 'Are you sure your connection is up?', "\n";
		 }

		print "Current IP address is: $currentIPAddress", "\n";
	}
}

# checks

if ( $oldIPAddress =~ /$currentIPAddress/) {
	print 'Warning: Old and new IP addresses match. Reconnect.', "\n";
}
 else {
	print 'Success. IP addresses are different.', "\n";
}	
 
# logs current IP
open $IPLOG, ">", $log_filename;
print $IPLOG $ip_address;
close $IPLOG;