NetPacket::PFLog(3p)

NAME
"NetPacket::PFLog" - Assembling and disassembling OpenBSD's Packet Filter log header.

SYNOPSIS
  use NetPacket::PFLog;

  $pfl_obj = NetPacket::PFLog->decode($raw_pkt);
  $pfl_pkt = NetPacket::PFLog->encode();
  $pfl_data = NetPacket::PFLog::strip($raw_pkt);

DESCRIPTION
"NetPacket::PFLog" provides a set of routines for assembling and disassembling the header attached to packets logged by OpenBSD's Packet Filter.

  Methods

"NetPacket::PFLog->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::PFLog->encode()"
    Return a PFLog packet encoded with the instance data specified.

  Functions

"NetPacket::PFLog::strip([RAW PACKET])"
    Return the actual packet logged by Packet Filter that the PFLog header is describing. 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::PFLog" object consists of the following fields:

len The length of the pflog header.

af  The Address Family which denotes if the packet is IPv4 or IPv6.

action
    The action (block, pass, or scrub) that was taken on the packet.

reason
    The reason that the action was taken.

ifname
    The name of the interface the packet was passing through.

ruleset
    The name of the subruleset that the matching rule is a member of. If the value is empty, the matching rule is in the main ruleset.

rulenr
    The rule number that the packet matched.

subrulenr
    The rule number in the subruleset that the packet matched. The value will be 2^32-1 if the packet matched in the main ruleset only.

uid The uid of the process that inserted the rule that caused the packet to be logged.

pid The pid of the process that inserted the rult that caused the packet to be logged.

rule_uid
    The uid of the local process that generated the packet that was logged, if applicable.

rule_pid
    The pid of the local process that generated the packer that was logged, if applicable.

dir The direction the packet was travelling through the interface.

pad Padding data.

data
    The actual IPv4 or IPv6 packet that was logged by Packet Filter.

  Exports

default
    none

exportable
    Data Link Type:

      DLT_PFLOG

    Strip function:

      pflog_strip

tags
    The following tags can be used to export certain items:

    ":DLT"
        DLT_PFLOG

    ":strip"
        The function "pflog_strip"

    ":ALL"
        All the above exportable items

EXAMPLE
The following prints the action, direction, interface name, and reason:

  #!/usr/bin/perl -w

  use strict;
  use Net::PcapUtils;
  use NetPacket::PFLog;

  sub process_pkt {
      my ($user, $hdr, $pkt) = @_;

      my $pfl_obj = NetPacket::PFLog->decode($pkt);
      print("$pfl_obj->{action} $pfl_obj->{dir} ");
      print("on $pfl_obj->{ifname} ($pfl_obj->{reason})\n");
  }

  Net::PcapUtils::loop(\&process_pkt, FILTER => 'ip or ip6');

TODO
Nothing at this time.

COPYRIGHT
Copyright (c) 2003, 2004 Joel Knight <enabled@myrealbox.com>

Permission to use, copy, modify, and distribute this software for any purpose with or without fee is hereby granted, provided that the above copyright notice and this permission notice appear in all copies.

THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

AUTHOR
Joel Knight <enabled@myrealbox.com>