NAME

NetPacket::ICMP - Assemble and disassemble ICMP (Internet Control Message Protocol) packets.

VERSION

version 1.7.2

SYNOPSIS

use NetPacket::ICMP;

$icmp_obj = NetPacket::ICMP->decode($raw_pkt);
$icmp_pkt = NetPacket::ICMP->encode();
$icmp_data = NetPacket::ICMP::strip($raw_pkt);

DESCRIPTION

NetPacket::ICMP provides a set of routines for assembling and disassembling packets using ICMP (Internet Control Message Protocol).

Methods

NetPacket::ICMP->decode([RAW PACKET])

Decode the raw packet data given and return an object containing instance data. This method will quite happily decode garbage input. It is the responsibility of the programmer to ensure valid packet data is passed to this method.

NetPacket::ICMP->encode()

Return an ICMP packet encoded with the instance data specified.

Functions

NetPacket::ICMP::strip([RAW PACKET])

Return the encapsulated data (or payload) contained in the ICMP packet.

Instance data

The instance data for the NetPacket::ICMP object consists of the following fields.

type

The ICMP message type of this packet.

code

The ICMP message code of this packet.

cksum

The checksum for this packet.

data

The encapsulated data (payload) for this packet.

Exports

default

none

exportable

ICMP message types: ICMP_ECHOREPLY ICMP_UNREACH ICMP_SOURCEQUENCH ICMP_REDIRECT ICMP_ECHO ICMP_ROUTERADVERT ICMP_ROUTERSOLICIT ICMP_TIMXCEED ICMP_PARAMPROB ICMP_TSTAMP ICMP_TSTAMPREPLY ICMP_IREQ ICMP_IREQREPLY ICMP_MASKREQ ICMP_MASKREPLY

tags

The following tags group together related exportable items.

:types

ICMP_ECHOREPLY ICMP_UNREACH ICMP_SOURCEQUENCH
ICMP_REDIRECT ICMP_ECHO ICMP_ROUTERADVERT
ICMP_ROUTERSOLICIT ICMP_TIMXCEED ICMP_PARAMPROB
ICMP_TSTAMP ICMP_TSTAMPREPLY ICMP_IREQ
ICMP_IREQREPLY ICMP_MASKREQ ICMP_MASKREPLY

:strip

Import the strip function icmp_strip.

:ALL

All the above exportable items.

EXAMPLE

The following example prints the ICMP type, code, and checksum fields.

#!/usr/bin/perl -w

use strict;
use Net::PcapUtils;
use NetPacket::Ethernet qw(:strip);
use NetPacket::IP qw(:strip);
use NetPacket::ICMP;

sub process_pkt {
    my ($user, $hdr, $pkt) = @_;

    my $ip_obj = NetPacket::IP->decode(eth_strip($pkt));
    my $icmp_obj = NetPacket::ICMP->decode(ip_strip($ip_obj));

    print("Type: $icmp_obj->{type}\n");
    print("Code: $icmp_obj->{code}\n");
    print("Checksum: $icmp_obj->{cksum}\n\n");
}

Net::PcapUtils::loop(\&process_pkt, FILTER => 'icmp');

TODO

Create constants

COPYRIGHT

Copyright (c) 2001 Tim Potter and Stephanie Wehner.

Copyright (c) 1995,1996,1997,1998,1999 ANU and CSIRO on behalf of the participants in the CRC for Advanced Computational Systems ('ACSys').

This module is free software. You can redistribute it and/or modify it under the terms of the Artistic License 2.0.

This program is distributed in the hope that it will be useful, but without any warranty; without even the implied warranty of merchantability or fitness for a particular purpose.

AUTHOR

Tim Potter <tpot@samba.org>

Stephanie Wehner <atrak@itsx.com>