bpa has asked for the wisdom of the Perl Monks concerning the following question:

Hello Monks,

I recently posted with some issues getting the Net::Packet module and some of its dependencies installed on my Ubuntu 8.04 box. The monks were very helpful and with their help, I quickly resoved my installation issues. I am hoping someone can help me with this as well. I am using Net::Packet-3.26 on kernel 2.6.24-20.

The reason I tried the install on Ubuntu was because I was having problems sending out IPv6 packets on Slackware, but Ubuntu is giving me the exact error which is:

UPDATE: Sorry, I uncommented the initialization of $env and reposted the output. 
addr_net: undef input
env->ip6: ::1
Env->ip6: ::1
NP_IPv6_PROTOCOL_TCP: 6
Use of uninitialized value in socket at /usr/local/share/perl/5.8.8/Ne
+t/Write/Layer.pm line 171.
Net::Write::Layer::open: socket: Address family not supported by proto
+col
 at /usr/local/share/perl/5.8.8/Net/Packet/DescL3.pm line 86

[download]


Here is my code:

#!/usr/bin/perl

# Author: Barret Miller
# Date: 07/14/08 (date of E3 gaming conference!)
# This program will send either a UDP or TCP packet with a faked
# source address to a destination address for IPv4 or IPv6

use Switch;
use Net::Packet::Env qw($Env);
use Net::Packet::Consts qw(:ipv6);
require Net::Packet::Frame;
require Net::Packet::DescL3;
require Net::Packet::Dump;
require Net::Packet::IPv4;
require Net::Packet::IPv6;
require Net::Packet::UDP;
require Net::Packet::TCP;

my $transport;
my $port;
my $version;
my $ip;
my $l4;
my $srcAddr;
my $dstAddr;
my $if;

handleArgs(@ARGV);

my $env = Net::Packet::Env->new(dev => $if);

print("env->ip6: " . $Env->ip6 . "\n");
print("Env->ip6: " . $Env->ip6 . "\n");
print("NP_IPv6_PROTOCOL_TCP: " . NP_IPv6_PROTOCOL_TCP . "\n");

#my $desc = Net::Packet::DescL3->new(
#    target => '192.168.1.99',
#);

my $dump = Net::Packet::Dump->new(
    keepTimestamp => 1,
    env => $env,
);

$dump->start;

my $d3 = Net::Packet::DescL3->new(
    dev => 'wlan0',
    target => '::1',
);

# Build network layer header (ip4 or ip6)
# defualts to ip4
if($version eq '6')
{    
    $ip = Net::Packet::IPv6->new(
        src => '::1',
        dst => '::1',
        nextHeader => NP_IPv6_PROTOCOL_TCP,
    );
}
else
{
    $ip = Net::Packet::IPv4->new(
        src => $srcAddr,
        dst => $dstAddr,
    );
}

# Build a transport layer header
# defaults to tcp
if($transport eq 'udp')
{
    $l4 = Net::Packet::UDP->new(
        dst => $port,
    );
}
else
{
    $l4 = Net::Packet::TCP->new(
        dst => $port,
    );
}

# Assemble a frame
my $frame = Net::Packet::Frame->new(
    l3 => $ip,
    l4 => $l4,
);

$frame->send;

# Note: if you have faked your address, don't expect a 
# reply!
if($transport eq 'tcp')
{
    until($dump->timeout)
    {
        if($frame->recv)
        {
            print $frame->reply->l3, "\n";
            print $frame->reply->l4, "\n";
            last;
        }
    }
}

# clean up crap files
$dump->stop;
$dump->clean;

# Handle command line args
sub handleArgs
{
    my @args = @_;
    my $argsLength = @args;

    if($argsLength < 6)
    {
        printUsage();
        die "Incorrect arguments\n";
    }
    else
    {
        for(my $i = 0; $i < $argsLength; $i++)
        {
            my $arg = $args[$i];

            switch($arg)
            {
                # Port to send to
                case "-p"
                {
                    $port = $args[$i + 1];
                    $i++;
                }
                # IP version number
                case "-v"
                {
                    $version = $args[$i + 1];
                    $i++;
                }
                # transport layer protocol
                case "-t"
                {
                    $l4 = $args[$i + 1];
                    $i++;
                }
                case "-s"
                {
                    $srcAddr = $args[$i + 1];
                    $i++;
                }
                case "-d"
                {
                    $dstAddr = $args[$i + 1];
                    $i++;
                }
                case "-i"
                {
                    $if = $args[$i + 1];
                    $i++;
                }
                else
                {
                    printUsage();
                }
            }
        }
    }
}

sub printUsage
{
    print("USAGE: \n" . 
          "sendPacket [-v 4|6] [-t tcp|udp] [-s srcAddr]\n" .
          "-i iface -p dstPort  -d dstAddr\n");
}

[download]


I have no problem sending out an IPv4 packet, and when sniffing the network, this module has no problem disecting IPv6 packets, but I am begining to wonder if it is possible to inject IPv6 packets to the network.

Any help is greatly appreciated.

Barret

Replies are listed 'Best First'.
Re: Problem Sending an IPv6 Packet with Net::Packet Module
by Anonymous Monk on Jul 24, 2008 at 03:58 UTC
    Did you run the test suite ? What did you get?
[reply]
      Hi, sorry for the long time it has taken me to respond since you posted, but thank you. I'm not sure what you mean by the test suite. I did attempt to run the ip6-syn-send.pl example program that came with the Net::Packet module, and it executes without error as my script does now, but I can't pick up anything when sniffing the interface. With my program I can send IPv4 packets just fine and I can sniff them on the source and receiving host, but no such luck with an IPv6 packet.

      I do thank you for your suggestion because when I looked into the ip6-syn-send.pl sample script to see why it was not getting any error message, I saw that it was creating a layer 2 eth object explicitly and giving it a destination mac address. Once I created this object in my code, and included it when creating the frame object, that got rid of my error. However, like I said I still cannot see any IPv6 frames traversing the wire despite the lack of error messages. Here is my updated code: 
      #!/usr/bin/perl

# This program will send either a UDP or TCP packet with a faked
# source address to a destination address for IPv4 or IPv6
use strict;
use warnings;

use Switch;
use Net::Packet::Env qw($Env);
use Net::Packet::Consts qw(:ipv6 :eth);
require Net::Packet::Frame;
require Net::Packet::DescL3;
require Net::Packet::Dump;
require Net::Packet::IPv4;
require Net::Packet::IPv6;
require Net::Packet::UDP;
require Net::Packet::TCP;
require Net::Packet::ETH;

my $transport;
my $port;
my $version;
my $eth;
my $ip;
my $l4;
my $frame;
my $srcAddr;
my $dstAddr;
my $if;

handleArgs(@ARGV);

printEnv();

my $env = Net::Packet::Env->new(dev => $if);

my $dump = Net::Packet::Dump->new(
    keepTimestamp => 1,
    env => $env,
);

$dump->start;

# Build network layer header (ip4 or ip6)
# defualts to ip4
if($version eq '6')
{    
    $eth = Net::Packet::ETH->new(
        type => NP_ETH_TYPE_IPv6,
        dst => '00:B0:D0:7B:BC:AE',
    );
    $ip = Net::Packet::IPv6->new(
        src => $srcAddr,
        dst => $dstAddr,
    );
}
else
{
    $ip = Net::Packet::IPv4->new(
        src => $srcAddr,
        dst => $dstAddr,
    );
}

# Build a transport layer header
# defaults to tcp
if($transport eq 'udp')
{
    $l4 = Net::Packet::UDP->new(
        dst => $port,
    );
}
else
{
    $l4 = Net::Packet::TCP->new(
        dst => $port,
    );
}

# Assemble a frame
if($version eq '6')
{
    $frame = Net::Packet::Frame->new(
        l2 => $eth,
        l3 => $ip,
        l4 => $l4,
    );
}
else
{
    $frame = Net::Packet::Frame->new(
        l3 => $ip,
        l4 => $l4,
    );
}

$frame->send;

# Note: if you have faked your address, don't expect a 
# reply!
if($transport eq 'tcp')
{
    until($dump->timeout)
    {
        if($frame->recv)
        {
            print $frame->reply->l3, "\n";
            print $frame->reply->l4, "\n";
            last;
        }
    }
}

# clean up crap files
$dump->stop;
$dump->clean;

# Handle command line args
sub handleArgs
{
    my @args = @_;
    my $argsLength = @args;

    if($argsLength < 6)
    {
        printUsage();
        die "Incorrect arguments\n";
    }
    else
    {
        for(my $i = 0; $i < $argsLength; $i++)
        {
            my $arg = $args[$i];

            switch($arg)
            {
                # Port to send to
                case "-p"
                {
                    $port = $args[$i + 1];
                    $i++;
                }
                # IP version number
                case "-v"
                {
                    $version = $args[$i + 1];
                    $i++;
                }
                # transport layer protocol
                case "-t"
                {
                    $transport = $args[$i + 1];
                    $i++;
                }
                case "-s"
                {
                    $srcAddr = $args[$i + 1];
                    $i++;
                }
                case "-d"
                {
                    $dstAddr = $args[$i + 1];
                    $i++;
                }
                case "-i"
                {
                    $if = $args[$i + 1];
                    $i++;
                }
                else
                {
                    printUsage();
                }
            }
        }
    }
}

sub printUsage
{
    print("USAGE: \n" . 
          "sendPacket [-v 4|6] [-t tcp|udp] [-s srcAddr]\n" .
          "-i iface -p dstPort  -d dstAddr\n");
}

sub printEnv
{
    print("transport: $transport\n");
    print("port:  $port\n");
    print("version:  $version\n");
    print("srcAddr: $srcAddr\n");
    print("dstAddr: $dstAddr\n");
    print("if: $if\n");

}

      [download]


      To send an IPv4 tcp packet: 
      sudo ./sendPacket.pl -v 4 -t tcp -s 192.168.1.93 -i eth0 -p 25 -d 192.
+168.1.90

      [download]


      To send an IPv6 tcp packet: 
      sudo ./sendPacket.pl -v 6 -t tcp -s fe80::21c:23ff:fefe:5b7e -i eth0 -
+p 25 -d fe80::2b0:d0ff:fe7b:bcae

      [download]


      Obviously change the source and destination addresses to something relevant to your setup and only have to use sudo on Ubuntu. Thanks for any help.
[reply]
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