Patrice Auffret > Net-Packet > Net::Packet::Env

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NAME ^

Net::Packet::Env - environment object used for frame capture/injection

SYNOPSIS ^

   use Net::Packet::Env qw($Env);

   # Get default values from system
   my $env = Net::Packet::Env->new;

   # Get values from a specific device
   my $env2 = Net::Packet::Env->new(dev => 'vmnet1');

   print "dev: ", $env->dev, "\n";
   print "mac: ", $env->mac, "\n";
   print "ip : ", $env->ip,  "\n" if $env->ip;
   print "ip6: ", $env->ip6, "\n" if $env->ip6;

DESCRIPTION ^

Basically, this module is used to tell where to inject a frame, and Net::Packet::Frame default behaviour regarding auto creation of Net::Packet::Desc and Net::Packet::Dump objects.

ATTRIBUTES ^

dev

The device on which frames will be injected.

ip

The IPv4 address of dev. It will be used by default for all created frames.

ip6

The IPv6 address of dev. It will be used by default for all created frames.

mac

The MAC address of dev. It will be used by default for all created frames.

subnet

The subnet address of dev. It will be set automatically.

gatewayIp

The gateway IP address of dev. It is set automatically under all platforms.

gatewayMac

The gateway MAC address of dev. It will not be set automatically. Due to the implementation of ARP lookup within Net::Packet, we can't do it within this module. It is done within Net::Packet::DescL3 under Windows, to automatically build the layer 2 header.

desc

The Net::Packet::Desc object used to inject frames to network.

dump

The Net::Packet::Dump object used to receive frames from network.

noFrameAutoDesc

This attribute controls Net::Packet::Frame behaviour regarding Net::Packet::Desc autocreation. If set to 0, when a Net::Packet::Frame is created for the first time, a Net::Packet::Desc object will be created if none has been set in desc attribute for default $Env object. Setting it to 1 avoids this behaviour.

noFrameAutoDump

Same as above, but for Net::Packet::Dump object.

noDescAutoSet

This attribute controls Net::Packet::Desc behaviour regarding global $Env autosetting behaviour. If set to 0, when a Net::Packet::Desc is created for the first time, the created Net::Packet::Desc object will have a pointer to it stored in desc attribute of $Env default object. Setting it to 1 avoids this behaviour.

noDumpAutoSet

Same as above, but for Net::Packet::Dump object.

noFramePadding

By default, when a Net::Packet::Frame object is created from analyzing a raw string (either by taking from Net::Packet::Dump object or from user), padding is achieved to complete the size of 60 bytes. Set this attribute to 1 if you do not want this behaviour.

doFrameReturnList

By default, when a Net::Packet::Frame object is created from analyzing a raw string (either by taking from Net::Packet::Dump object or from user), only the first found frame is returned. If you set it to true, an arrayref of Net::Packet::Frame objects will be returned. For example, if you put an IPv6 frame within IPv4, or you get one from network, you will need to use this attribute.

noFrameComputeChecksums
noFrameComputeLengths

By default, when a Net::Packet::Frame object is packed, all layers checksums and lengths are computed (if respective layers implement that). If you want to do it yourself, set this to true. See doIPv4Checksum for the exception.

doIPv4Checksum

This parameter exists to improve performances of the framework. When you send an IPv4 frame at layer 3 (using a Net::Packet::DescL3 object), under Unix systems, you MUST not compute IPv4 checksum. The kernel does it. Because this is the more general case (sending IPv4 at layer 3), this parameter is set to false by default. Note: under Windows, because Net::Packet::DescL3 is a wrapper around Net::Packet::DescL2, this parameter will be set to true on Net::Packet::DescL3 object creation.

So, even if you let the framework compute checksums, IPv4 checksum will not be computed. If you want to send IPv4 frames at layer 2, you will need to also set this parameter to true.

doMemoryOptimizations

By default, no memory optimizations are made to improve speed. You can enable those optimizations (mostly done in Net::Packet::Frame) in order to gain ~ 10% in memory, at the cost of ~ 10% in speed.

debug

The environment debug directive. Set it to a number greater than 0 to increase the level of debug messages. Up to 3, default 0.

METHODS ^

new

Object constructor. You can pass attributes that will overwrite default ones. Default values:

debug: 0

noFrameAutoDesc: 0

noFrameAutoDump: 0

noDescAutoSet: 0

noDumpAutoSet: 0

dev: if not user provided, default interface is used, by calling getDevInfo method. If user provided, all ip, ip6 and mac attributes will be used for that dev.

ip: if not user provided, default interface IP is used, by calling getIp method. If user provided, it is overwritten by the user.

ip6: if not user provided, default interface IPv6 is used, by calling getIp6 method. If user provided, it is overwritten by the user.

mac: if not user provided, default interface MAC is used, by calling getMac method. If user provided, it is overwritten by the user.

getDevInfo [ (scalar) ]

By default, network device to use is the one used by default gateway. If you provide an IP address as a parameter, the interface used will be the one which have direct access to this IP address.

getDevInfoFor (scalar)

Will set internal attributes for network interface passed as a parameter. Those internal attributes are used to get IP, IPv6 and MAC attributes.

updateDevInfo (scalar)

This is a helper method. You pass an IP address as a parameter, and all attributes for elected network interface will be updated (dev, ip, ip6, mac, subnet, gatewayIp).

getDev

Returns network interface, by looking at internal attribute.

getMac

Returns MAC address, by looking at internal attribute.

getSubnet

Returns subnet address, by looking at internal attribute.

getIp

Returns IP address, by looking at internal attribute.

getIp6

Returns IPv6 address, by looking at internal attribute.

AUTHOR ^

Patrice <GomoR> Auffret

COPYRIGHT AND LICENSE ^

Copyright (c) 2004-2009, Patrice <GomoR> Auffret

You may distribute this module under the terms of the Artistic license. See LICENSE.Artistic file in the source distribution archive.

RELATED MODULES ^

NetPacket, Net::RawIP, Net::RawSock

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