conntrack-burn.pl

#!/usr/bin/perl -w
# Original source: https://lkml.org/lkml/2016/12/7/114
# Changesd to ping the whole 8.8.x.x subnet to produce lots of entries.

my $subnet = '8.8';

use Socket;
use Symbol;
use NetAddr::IP::Lite;

sub ICMP_ECHO       ()  { 8 }
sub ICMP_SUBCODE    ()  { 0 }
sub ICMP_STRUCT     ()  { 'C2S3A56' }
sub ICMP_FLAGS      ()  { 0 }
sub ICMP_PORT       ()  { 0 }

$sequence=0;

for $j (1..255) {
  for $i (2..254) {

              $protocol = (getprotobyname('icmp'))[2] or
                 die('Cannot get ICMP protocol number by name - ', $!);

              $socket = Symbol::gensym;
              socket($socket, PF_INET, SOCK_RAW, $protocol) or
                  die('Cannot create IMCP socket - ', $!);


              $sequence = ($sequence+1) & 0xFFFF;

          my $checksum = 0;
  	my $msg = pack(
              ICMP_STRUCT,
  		ICMP_ECHO,
                  ICMP_SUBCODE,
  		$checksum,
                  $$ & 0xFFFF,
                  $sequence,
                  '0' x 56
  	);

  	my $short = int(length($msg) / 2);
          $checksum += $_ for unpack "S$short", $msg;
          $checksum += ord(substr($msg, -1)) if length($msg) % 2;
          $checksum = ($checksum >> 16) + ($checksum & 0xFFFF);
  	$checksum = ~(($checksum >> 16) + $checksum) & 0xFFFF;

  	$msg = pack(
              ICMP_STRUCT,
                  ICMP_ECHO,
  		ICMP_SUBCODE,
  		$checksum,
                  $$ & 0xFFFF,
  		$sequence,
                  '0' x 56
          );

  	my($address)=$single?$single:"$subnet.$j.$i";
          my $netaddr = inet_aton($address);
          my $sockaddr = pack_sockaddr_in(ICMP_PORT, $netaddr);
          send($socket, $msg, ICMP_FLAGS, $sockaddr) or
              die("ERROR ($address) sending ICMP packet - $!");
  }
}
print "OK\n";