NAME

NetPacket::ARP - Assemble and disassemble ARP (Address Resolution Protocol) packets.

VERSION

version 1.6.0

SYNOPSIS

  use NetPacket::ARP;

  $tcp_obj = NetPacket::ARP->decode($raw_pkt);
  $tcp_pkt = NetPacket::ARP->encode(params...);   # Not implemented

DESCRIPTION

"NetPacket::ARP" provides a set of routines for assembling and disassembling packets using ARP (Address Resolution Protocol).

Methods

"NetPacket::ARP->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::ARP->encode(param => value)": Return a ARP packet encoded with the instance data specified. Not implemented.

Functions

"NetPacket::ARP::strip([RAW PACKET])": Return the encapsulated data (or payload) contained in the TCP packet. Since no payload data is encapulated in an ARP packet (only instance data), this function returns undef.

Instance data

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

htype: Hardware type.
proto: Protocol type.
hlen: Header length.
plen: Protocol length.
opcode: One of the following constants:

ARP_OPCODE_REQUEST
ARP_OPCODE_REPLY
RARP_OPCODE_REQUEST
RARP_OPCODE_REPLY

sha: Source hardware address.
spa: Source protocol address.
tha: Target hardware address.
tpa: Target protocol address.

Exports

default: none
exportable: none
tags: The following tags group together related exportable items.

":ALL": All the above exportable items.

EXAMPLE

Print out arp requests on the local network.

  #!/usr/bin/perl -w

  use Net::PcapUtils;
  use NetPacket::Ethernet qw(:types);
  use NetPacket::ARP;

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

    my $eth_obj = NetPacket::Ethernet->decode($pkt);

    if ($eth_obj->{type} == ETH_TYPE_ARP) {
        my $arp_obj = NetPacket::ARP->decode($eth_obj->{data}, $eth_obj);
        print("source hw addr=$arp_obj->{sha}, " .
              "dest hw addr=$arp_obj->{tha}\n");
    }
  }

Net::PcapUtils::loop(\&process_pkt);

TODO

Implement encode() function
Does this work for protocols other than IP? Need to read RFC.
Example is a bit silly

COPYRIGHT

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>