#!/usr/bin/perl -w
# Blocks incoming connections on port 25 from the specified IP (with iptables)
# Usage: ./blockmailfromip aa.bb.cc.dd
# Author: Juan R. Pozo - http://html.conclase.net/cp/scripts/
# Released on December 8, 2003
###############################################################################
# This software is released into the public domain. Use at your own risk.
# The author holds no rights or responsibilities related to this software.
###############################################################################
# iptables -A INPUT -s aa.bb.cc.dd -p tcp --destination-port 25 -j DROP
###############################################################################

use strict;

if (scalar @ARGV != 1 || $ARGV[0] !~ /^(\d{1,3}\.){3}\d{1,3}$/) {
    die("Usage: ./blockmailfromip aa.bb.cc.dd\n");
}

my @check = `iptables -nL INPUT | grep $ARGV[0]`;
# DROP       tcp  --  aa.bb.cc.dd        0.0.0.0/0          tcp dpt:25
foreach (@check) {
    if (/^DROP\s+tcp\s+--\s+$ARGV[0]\s+0.0.0.0\/0\s+tcp dpt:25/) {
        die("Mail coming from specified IP is already being blocked.\n");
    }
}

print `iptables -A INPUT -s $ARGV[0] -p tcp --destination-port 25 -j DROP 2>&1`;
print "Done\n";
print `iptables -nL INPUT | grep $ARGV[0]`;

exit;