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.Dd October 29, 2021 27.Dt PFLOG 4 28.Os 29.Sh NAME 30.Nm pflog 31.Nd packet filter logging interface 32.Sh SYNOPSIS 33.Cd "device pflog" 34.Sh DESCRIPTION 35The 36.Nm pflog 37interface is a device which makes visible all packets logged by 38the packet filter, 39.Xr pf 4 . 40Logged packets can easily be monitored in real 41time by invoking 42.Xr tcpdump 1 43on the 44.Nm 45interface, or stored to disk using 46.Xr pflogd 8 . 47.Pp 48The pflog0 interface is created when the 49.Nm 50module is loaded; 51further instances can be created using 52.Xr ifconfig 8 . 53The 54.Nm 55module is loaded automatically if both 56.Xr pf 4 57and 58.Xr pflogd 8 59are enabled. 60.Pp 61Each packet retrieved on this interface has a header associated 62with it of length 63.Dv PFLOG_HDRLEN . 64This header documents the address family, interface name, rule 65number, reason, action, and direction of the packet that was logged. 66This structure, defined in 67.Aq Pa net/if_pflog.h 68looks like 69.Bd -literal -offset indent 70struct pfloghdr { 71 u_int8_t length; 72 sa_family_t af; 73 u_int8_t action; 74 u_int8_t reason; 75 char ifname[IFNAMSIZ]; 76 char ruleset[PF_RULESET_NAME_SIZE]; 77 u_int32_t rulenr; 78 u_int32_t subrulenr; 79 uid_t uid; 80 pid_t pid; 81 uid_t rule_uid; 82 pid_t rule_pid; 83 u_int8_t dir; 84 u_int8_t pad[3]; 85 u_int32_t ridentifier; 86}; 87.Ed 88.Sh EXAMPLES 89Create a 90.Nm 91interface 92and monitor all packets logged on it: 93.Bd -literal -offset indent 94# ifconfig pflog create 95pflog1 96# ifconfig pflog1 up 97# tcpdump -n -e -ttt -i pflog1 98.Ed 99.Sh SEE ALSO 100.Xr tcpdump 1 , 101.Xr inet 4 , 102.Xr inet6 4 , 103.Xr netintro 4 , 104.Xr pf 4 , 105.Xr ifconfig 8 , 106.Xr pflogd 8 107.Sh HISTORY 108The 109.Nm 110device first appeared in 111.Ox 3.0 . 112.Sh BUGS 113FreeBSD does not set a process id in the 114.Fa pid 115field in pfloghdr. 116