---
name: "NetPacket::ARP"
section: "3pm"
platform: "linux"
package: "libnetpacket-perl"
version: "1.7.2-2"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/NetPacket::ARP"
---

# NetPacket::ARP(3pm)

Assemble and disassemble ARP (Address Resolution Protocol) packets.

## NAME

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

## VERSION

version 1.7.2

## 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

Copyright (c) 2001 Tim Potter.

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\>