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  ## Need an IO::Handle to $kernel->select_read() upon
  $heap->{fdh} = IO::Handle->new_from_fd( $heap->{fd}, "r" )
    or die "Can't create IO::Handle from pcap fd: $!\n";


POE::Component::Pcap - POE Interface to Net::Pcap


  use POE::Component::Pcap;

                              Alias => 'pcap',
                              Device => 'eth0',
                              Filter => 'host fooble or host blort',
                              Dispatch => 'got_packet',
                              Session => $my_session_id,

  $poe_kernel->post( pcap => open_live =>
                     'eth0', 80, 1, 100 );

  $poe_kernel->post( pcap => set_filter => 'arp or host zooble' );

  $poe_kernel->post( pcap => set_dispatch => 'target_state' );

  $poe_kernel->post( pcap => 'run' );

  $poe_kernel->post( pcap => 'shutdown' );


POE::Component::Pcap provides a wrapper for using the Net::Pcap module from POE programs. The component creates a separate session which posts events to a specified session and state when packets are available.



The alias for the Pcap session. Used to post events such as run and shutdown to control the component. Defaults to pcap if not specified.


As a shortcut, the device for Net::Pcap to watch may be specified when creating the component. If this argument is used, Net::Pcap::open_live will be called with a snaplen of 80 octets, a timeout of 100ms, and the interface will be put in promiscuous mode. If these values are not suitable, post an open_live event instead.


Another shortcut, calls Net::Pcap::compile and Net::Pcap::setfilter to set a packet filter. This can only be used if the Device argument is also given; otherwise a set_filter event should be posted after an open_live event (since Net::Pcap must have a pcap_t descriptor to work with).


These specify the session and state to which events should be posted when packets are received.


The following examples assume that the component's alias has been set to the default value of pcap.

  $_[KERNEL]->post( pcap => open_live
                    => 'device', [snaplen], [promsic?], [timeout] );

Calls Net::Pcap::open_live. The device name must be specified. The snaplen, promiscuous, and timeout parameters default to 80, 1, and 100 respectively. This event must be posted (or the Device argument must have been passed to spawn()) before anything else can be done with the component.

  $_[KERNEL]->post( pcap => set_filter
                    => 'host fooble or host blort' )

Sets the Net::Pcap capture filter. See tcpdump(8) for details on the filter language used by pcap(3).

  $_[KERNEL]->post( pcap => set_dispatch
                    => 'target_state', 'target_session' );

Sets the state and session to which events are sent when packets are recevied. The target session will default to the sender of the event if not specified.

The event posted will have a single argument (available as ARG0) which will be an array reference containing the $hdr and $pkt parameters from Net::Pcap. See the Net::Pcap(3) documentation for more details.

  $_[KERNEL]->post( pcap => 'run' );

Causes the component to register a select_read and start watching for packets.

  $_[KERNEL]->post( pcap => 'shutdown' );

Shuts the component down. Causes Net::Pcap::close to be called.


Net::Pcap(3), pcap(3), tcpdump(8), POE(3), POE::Component(3)


Mike Fletcher, <>


Copyright 2000-2001, Mike Fletcher. All Rights Reserved. This is free software; you may redistribute it and/or modify it under the same terms as Perl itself.