#!/usr/bin/perl

use strict;
use Socket;
use Sys::Hostname;

my $local_port = shift or die "no port";
my $notify_email = shift or die "specify an email to notify";

my $eth1 = `/sbin/ifconfig eth1`;

my ($local_ip) = ($eth1 =~ /inet addr:(.*?)\s/);

socket(SERVER, PF_INET, SOCK_STREAM, getprotobyname('tcp'));

setsockopt(SERVER, SOL_SOCKET, SO_REUSEADDR, 1);

my $my_addr = sockaddr_in($local_port, INADDR_ANY);

bind(SERVER, $my_addr) or die "can't bind $!\n";

listen(SERVER, SOMAXCONN) or die "cant listen $!\n";

my $client_address;
while($client_address = accept(CLIENT, SERVER)) {
        my($port, $packed_ip) = sockaddr_in($client_address);
        my $remote_ip = inet_ntoa($packed_ip);
        my $date = `/bin/date`;
        my $data = qq{
IP address $remote_ip tried connection on machine $local_ip local port $local_port at $date
        };

	if (-e "/proc/net/ip_input") {
        	`/sbin/ipfwadm -I -i deny -S $remote_ip/32 -o`;
	        `/sbin/ipfwadm -O -i deny -D $remote_ip/32 -o`;
	}
	elsif (-e "/proc/net/ip_fwchains") {
		`/sbin/ipchains -I input -s $remote_ip/32 -l -j DENY`;
		`/sbin/ipchains -I output -d $remote_ip/32 -l -j DENY`;
	}

        `/bin/echo "$data" | /bin/mail -s "Connection on spy port" $notify_email`;

}

close(SERVER);