1.\" $OpenBSD: pflog.4,v 1.10 2007/05/31 19:19:51 jmc Exp $ 2.\" 3.\" Copyright (c) 2001 Tobias Weingartner 4.\" All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 15.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25.\" 26.\" $FreeBSD$ 27.\" 28.Dd October 29, 2021 29.Dt PFLOG 4 30.Os 31.Sh NAME 32.Nm pflog 33.Nd packet filter logging interface 34.Sh SYNOPSIS 35.Cd "device pflog" 36.Sh DESCRIPTION 37The 38.Nm pflog 39interface is a device which makes visible all packets logged by 40the packet filter, 41.Xr pf 4 . 42Logged packets can easily be monitored in real 43time by invoking 44.Xr tcpdump 1 45on the 46.Nm 47interface, or stored to disk using 48.Xr pflogd 8 . 49.Pp 50The pflog0 interface is created when the 51.Nm 52module is loaded; 53further instances can be created using 54.Xr ifconfig 8 . 55The 56.Nm 57module is loaded automatically if both 58.Xr pf 4 59and 60.Xr pflogd 8 61are enabled. 62.Pp 63Each packet retrieved on this interface has a header associated 64with it of length 65.Dv PFLOG_HDRLEN . 66This header documents the address family, interface name, rule 67number, reason, action, and direction of the packet that was logged. 68This structure, defined in 69.Aq Pa net/if_pflog.h 70looks like 71.Bd -literal -offset indent 72struct pfloghdr { 73 u_int8_t length; 74 sa_family_t af; 75 u_int8_t action; 76 u_int8_t reason; 77 char ifname[IFNAMSIZ]; 78 char ruleset[PF_RULESET_NAME_SIZE]; 79 u_int32_t rulenr; 80 u_int32_t subrulenr; 81 uid_t uid; 82 pid_t pid; 83 uid_t rule_uid; 84 pid_t rule_pid; 85 u_int8_t dir; 86 u_int8_t pad[3]; 87 u_int32_t ridentifier; 88}; 89.Ed 90.Sh EXAMPLES 91Create a 92.Nm 93interface 94and monitor all packets logged on it: 95.Bd -literal -offset indent 96# ifconfig pflog create 97pflog1 98# ifconfig pflog1 up 99# tcpdump -n -e -ttt -i pflog1 100.Ed 101.Sh SEE ALSO 102.Xr tcpdump 1 , 103.Xr inet 4 , 104.Xr inet6 4 , 105.Xr netintro 4 , 106.Xr pf 4 , 107.Xr ifconfig 8 , 108.Xr pflogd 8 109.Sh HISTORY 110The 111.Nm 112device first appeared in 113.Ox 3.0 . 114.Sh BUGS 115FreeBSD does not set a process id in the 116.Fa pid 117field in pfloghdr. 118