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

# NetPacket::IP(3pm)

Assemble and disassemble IP (Internet Protocol) packets.

## NAME

NetPacket::IP - Assemble and disassemble IP (Internet Protocol) packets.

## VERSION

version 1.7.2

## SYNOPSIS

```
  use NetPacket::IP;
  $ip_obj = NetPacket::IP->decode($raw_pkt);
  $ip_pkt = NetPacket::IP->encode($ip_obj);
  $ip_data = NetPacket::IP::strip($raw_pkt);
```

## DESCRIPTION

`"NetPacket::IP"` provides a set of routines for assembling and disassembling packets using IP (Internet Protocol).

### Methods

- "NetPacket::IP-\>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::IP-\>encode()"

  Return an IP packet encoded with the instance data specified. This will infer the total length of the packet automatically from the  payload length and also adjust the checksum.

### Functions

- "NetPacket::IP::strip(\[RAW PACKET\])"

  Return the encapsulated data (or payload) contained in the IP packet.  This data is suitable to be used as input for other `"NetPacket::*"` modules.

  This function is equivalent to creating an object using the `"decode()"` constructor and returning the `"data"` field of that object.

### Instance data

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

- ver

  The IP version number of this packet.

- hlen

  The IP header length of this packet.

- flags

  The IP header flags for this packet.

- foffset

  The IP fragment offset for this packet.

- tos

  The type-of-service for this IP packet.

- len

  The length (including length of header) in bytes for this packet.

- id

  The identification (sequence) number for this IP packet.

- ttl

  The time-to-live value for this packet.

- proto

  The IP protocol number for this packet.

- cksum

  The IP checksum value for this packet.

- src\_ip

  The source IP address for this packet in dotted-quad notation.

- dest\_ip

  The destination IP address for this packet in dotted-quad notation.

- options

  Any IP options for this packet.

- data

  The encapsulated data (payload) for this IP packet.

### Exports

- default

  none

- exportable

  IP\_PROTO\_IP IP\_PROTO\_ICMP IP\_PROTO\_IGMP IP\_PROTO\_IPIP IP\_PROTO\_TCP IP\_PROTO\_UDP IP\_VERSION\_IPv4

- tags

  The following tags group together related exportable items.

  - ":protos"

    IP\_PROTO\_IP IP\_PROTO\_ICMP IP\_PROTO\_IGMP IP\_PROTO\_IPIP IP\_PROTO\_TCP IP\_PROTO\_UDP

  - ":versions"

    IP\_VERSION\_IPv4

  - ":strip"

    Import the strip function `"ip_strip"`.

  - ":ALL"

    All the above exportable items.

## EXAMPLE

The following script dumps IP frames by IP address and protocol to standard output.

```
  #!/usr/bin/perl -w
  use strict;
  use Net::PcapUtils;
  use NetPacket::Ethernet qw(:strip);
  use NetPacket::IP;
  sub process_pkt {
      my ($user, $hdr, $pkt) = @_;
      my $ip_obj = NetPacket::IP->decode(eth_strip($pkt));
      print("$ip_obj->{src_ip}:$ip_obj->{dest_ip} $ip_obj->{proto}\n");
  }
  Net::PcapUtils::loop(\&process_pkt, FILTER => 'ip');
```

## TODO

- IP option decoding - currently stored in binary form.

  - Assembly of received fragments

  ## 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\>