Generates phontom connections in conntrack just as described in http://www.spinics.net/lists/netfilter/msg43912.html

conntrack_fuckup-phantom_connections.pl

#!/usr/bin/perl

my $target = '192.241.81.52';
my $port   = 80;
 
use DDP;
use Net::Frame::Device;
use Net::Write::Layer qw(:constants);
use Net::Write::Layer3;
use Net::Frame::Simple;
use Net::Frame::Dump::Online;

use Net::Frame::Layer::ETH qw(:consts);
use Net::Frame::Layer::IPv4 qw(:consts);
use Net::Frame::Layer::TCP qw(:consts);

 
# my $oDevice = Net::Frame::Device->new(target => $target);
my $oDevice = Net::Frame::Device->new(dev => "wlp3s0");

my $eth = Net::Frame::Layer::ETH->new(
   src  => $oDevice->mac,
   dst  => $oDevice->gatewayMac,
                                      type => NF_ETH_TYPE_IPv4,
                                     );
my $ip4 = Net::Frame::Layer::IPv4->new(
                                       src => $oDevice->ip,
                                       dst => $target,
                                      );
my $tcp = Net::Frame::Layer::TCP->new(
                                      flags   => NF_TCP_FLAGS_SYN, 
                                      dst     => $port,
                                     );
my $oWrite = Net::Write::Layer2->new(
                                     dev => $oDevice->dev,
                                    );
 
my $oDump = Net::Frame::Dump::Online->new(dev => $oDevice->dev);
$oDump->start;
 
my $oSimple = Net::Frame::Simple->new(
                                      layers => [ $eth, $ip4, $tcp ],
                                     );
$oWrite->open;
$oSimple->send($oWrite);
 
until ($oDump->timeout) {
    if (my $recv = $oSimple->recv($oDump)) {
        print "RECV:\n".$recv->print."\n";
        my @x=$recv->layers;
        my $reply_tcp=$x[2];
        $tcp = Net::Frame::Layer::TCP->new(
                                           src     => $tcp->src,
                                           dst     => $tcp->dst,
                                           ack     => $reply_tcp->seq+1,
                                           seq     => $tcp->seq,
                                           flags   => NF_TCP_FLAGS_ACK,
                                          );
        $oSimple = Net::Frame::Simple->new( layers => [ $eth, $ip4, $tcp ] );
        $oSimple->send($oWrite);

        sleep 1;

        $tcp = Net::Frame::Layer::TCP->new(
                                           src     => $tcp->src,
                                           dst     => $tcp->dst,
                                           ack     => $reply_tcp->seq+2,
                                           seq     => $tcp->seq+1,
                                           flags   => NF_TCP_FLAGS_FIN,
                                          );
        $oSimple = Net::Frame::Simple->new( layers => [ $eth, $ip4, $tcp ] );
        $oSimple->send($oWrite);
        
        last
    }
}

$oWrite->close;
$oDump->stop;

Don't exactly know why, but when I was using interface for my ethernet connection, kernel ways replying RST before my script could reply ACK, even though it is a RAW socket. This issue was not happening when I was using wifi interface - probably some kernel setting that I'm missing.