PFLOG(4)                  OpenBSD Programmer's Manual                 PFLOG(4)

NAME
     pflog - packet filter logging interface

SYNOPSIS
     pseudo-device pflog

DESCRIPTION
     The pflog interface is a pseudo-device which makes visible all packets
     logged by the packet filter, pf(4).  Logged packets can easily be moni-
     tored in real time by invoking tcpdump(8) on the pflog 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, inter-
     face name, rule number, reason, action, and direction of the packet that
     was logged.  This structure, defined in <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 pflog 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(8)

HISTORY
     The pflog device first appeared in OpenBSD 3.0.

OpenBSD 4.7                      May 31, 2007                                1
