pflog (4)

Leading comments

	$OpenBSD: pflog.4,v 1.10 2007/05/31 19:19:51 jmc Exp $

 Copyright (c) 2001 Tobias Weingartner
 All rights reserved.

 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions
 are met:
 1. Redistributions of source code must retain the above copyright
    notice, this list of conditions and the following disclaimer.
 2. Redistributions in binary form must reproduce the above copyright
    notice, this list of cond...

(The comments found at the beginning of the groff file "man4/pflog.4freebsd".)

NAME

pflog - packet filter logging interface

SYNOPSIS

device pflog

DESCRIPTION

The pflog interface is a device which makes visible all packets logged by the packet filter, pf(4). Logged packets can easily be monitored in real time by invoking tcpdump(1) on the ifconfig interface, or stored to disk using pflogd(8).

The pflog0 interface is created automatically at boot if both pf(4) and pflogd(8) are enabled; further instances can be created using ifconfig(8).

Each packet retrieved on this interface has a header associated with it of length PFLOG_HDRLEN This header documents the address family, interface name, rule number, reason, action, and direction of the packet that was logged. This structure, defined in Aq Pa net/if_pflog.h looks like

struct pfloghdr {
        u_int8_t        length;
        sa_family_t     af;
        u_int8_t        action;
        u_int8_t        reason;
        char            ifname[IFNAMSIZ];
        char            ruleset[PF_RULESET_NAME_SIZE];
        u_int32_t       rulenr;
        u_int32_t       subrulenr;
        uid_t           uid;
        pid_t           pid;
        uid_t           rule_uid;
        pid_t           rule_pid;
        u_int8_t        dir;
        u_int8_t        pad[3];
};

EXAMPLES

Create a ifconfig interface and monitor all packets logged on it:

# ifconfig pflog1 up
# tcpdump -n -e -ttt -i pflog1

SEE ALSO

inet(4), inet6(4), netintro(4), pf(4), ifconfig(8), pflogd(8), tcpdump(1)

HISTORY

The ifconfig device first appeared in Ox 3.0 .