Net::Frame::Dump::Online(3) tcpdump like implementation, online mode


use Net::Frame::Dump::Online;
# Simply create a Dump object
my $oDump = Net::Frame::Dump::Online->new(
dev => 'eth0',
# Gather frames
while (1) {
if (my $f = $oDump->next) {
my $raw = $f->{raw};
my $firstLayerType = $f->{firstLayer};
my $timestamp = $f->{timestamp};
# Create a Dump object, using on-event loop
sub callOnRecv {
my ($h, $data) = @_;
print "Data: $data\n";
my $oSimple = Net::Frame::Simple->newFromDump($h);
print $oSimple->print."\n";
my $oDumpEvent = Net::Frame::Dump::Online->new(
dev => 'eth0',
onRecv => \&callOnRecv,
onRecvCount => 1,
onRecvData => 'test',
# Will block here, until $onRecvCount packets read, or a stop() call has
# been performed.
# Default parameters on creation
my $oDumpDefault = Net::Frame::Dump::Online->new(
dev => undef,
timeoutOnNext => 3,
timeout => 0,
promisc => 0,
unlinkOnStop => 1,
file => "netframe-tmp-$$.$int.pcap",
filter => '',
overwrite => 0,
isRunning => 0,
keepTimestamp => 0,
onRecvCount => -1,
frames => [],


This module implements a tcpdump-like program, for live capture from networks.


The network interface to listen on. No default value.
Each time you call next method, an internal counter is updated. This counter tells you if you have not received any data since timeoutOnNext seconds. When a timeout occure, timeout is set to true.
When timeoutOnNext seconds has been reached, this variable is set to true, and never reset. See timeoutReset if you want to reset it.
If you want to capture a different snaplen, set it a number. Default to 1514.
By default, interface is not put into promiscuous mode, set this parameter to true if you want it.
When you call stop method, the generated .pcap file is removed, unless you set this parameter to a false value.
If you place a reference to a sub in this attribute, it will be called each time a packet is received on the interface. See SYNOPSIS for an example usage.
This parameter will store additional data to be passed to onRecv callback.
By default, it is set to read forever packets that reach your network interface. Set it to a positive value to read only onRecvCount frames.

The following are inherited attributes:

Name of the generated .pcap file. See SYNOPSIS for the default name.
Pcap filter to use. Default to no filter.
Overwrites a .pcap file that already exists. Default to not.
Stores information about the first layer type contained on read frame. This attribute is filled only after a call to start method.
Returns true if a call to start has been done, false otherwise or if a call to stop has been done.
Sometimes, when frames are captured and saved to a .pcap file, timestamps sucks. That is, you send a frame, and receive the reply, but your request appear to have been sent after the reply. So, to correct that, you can use Net::Frame::Dump own timestamping system. The default is 0. Set it manually to 1 if you need original .pcap frames timestamps.


new (hash)
Object constructor. You can pass attributes that will overwrite default ones. See SYNOPSIS for default values.
When you want to start reading frames from network, call this method.
When you want to stop reading frames from network, call this method.
Returns the next captured frame; undef if none awaiting. Each time this method is called, a comparison is done to see if no frame has been captured during timeoutOnNext number of seconds. If so, timeout attribute is set to 1 to reflect the pending timeout.
store (Net::Frame::Simple object)
This method will store internally, sorted, the Net::Frame::Simple object passed as a single parameter. getKey methods, implemented in various Net::Frame::Layer objects will be used to efficiently retrieve (via getKeyReverse method) frames.

Basically, it is used to make recv method (from Net::Frame::Simple) to retrieve quickly the reply frame for a request frame.

getFramesFor (Net::Frame::Simple object)
This will return an array of possible reply frames for the specified Net::Frame::Simple object. For example, reply frames for a UDP probe will be all the frames which have the same source port and destination port as the request.
Will flush stored frames, the one which have been stored via store method.
Reset the internal timeout state (timeout attribute).
Tries to get packet statistics on an open descriptor. It returns a reference to a hash that has to following fields: ps_recv, ps_drop, ps_ifdrop.
These methods will tell you if your current process is respectively the father, or son process of Net::Frame::Dump::Online object.


Patrice <GomoR> Auffret


Copyright (c) 2006-2014, Patrice <GomoR> Auffret

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