"NetPacket::IP" - Assemble and disassemble IP (Internet Protocol) packets. use NetPacket::IP; $ip_obj = NetPacket::IP->decode($raw_pkt); $ip_pkt = NetPacket::IP->encode(); $ip_data = NetPacket::IP::strip($raw_pkt); "NetPacket::IP" provides a set of routines for assembling and disassembling packets using IP (Internet Protocol).

Methods
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. 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
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. The IP version number of this packet. The IP header length of this packet. The IP header flags for this packet. The IP fragment offset for this packet. The type-of-service for this IP packet. The length (including length of header) in bytes for this packet. The identification (sequence) number for this IP packet. The time-to-live value for this packet. The IP protocol number for this packet. The IP checksum value for this packet. The source IP address for this packet in dotted-quad notation. The destination IP address for this packet in dotted-quad notation. Any IP options for this packet. The encapsulated data (payload) for this IP packet.

Exports
none IP_PROTO_IP IP_PROTO_ICMP IP_PROTO_IGMP IP_PROTO_IPIP IP_PROTO_TCP IP_PROTO_UDP IP_VERSION_IPv4 The following tags group together related exportable items. IP_PROTO_IP IP_PROTO_ICMP IP_PROTO_IGMP IP_PROTO_IPIP IP_PROTO_TCP IP_PROTO_UDP IP_VERSION_IPv4 Import the strip function "ip_strip". All the above exportable items. 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'); Copyright (c) 2001 Tim Potter. This package is free software and is provided "as is" without express or implied warranty. It may be used, redistributed and/or modified under the terms of the Perl Artistic License (see http://www.perl.com/perl/misc/Artistic.html) Copyright (c) 1995,1996,1997,1998,1999 ANU and CSIRO on behalf of the participants in the CRC for Advanced Computational Systems ('ACSys'). ACSys makes this software and all associated data and documentation ('Software') available free of charge. You may make copies of the Software but you must include all of this notice on any copy. The Software was developed for research purposes and ACSys does not warrant that it is error free or fit for any purpose. ACSys disclaims any liability for all claims, expenses, losses, damages and costs any user may incur as a result of using, copying or modifying the Software. Tim Potter <tpot@samba.org> Stephanie Wehner <atrak@itsx.com>