PFLOG(4)               FreeBSD Kernel Interfaces Manual               PFLOG(4)

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 pflog interface, or stored to disk
     using pflogd(8).

     The pflog0 interface is created when the pflog module is loaded; further
     instances can be created using ifconfig(8).  The pflog module is loaded
     automatically if both pf(4) and pflogd(8) are enabled.

     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 <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];
                   u_int32_t       ridentifier;
           };

EXAMPLES
     Create a pflog interface and monitor all packets logged on it:

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

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

HISTORY
     The pflog device first appeared in OpenBSD 3.0.

BUGS
     FreeBSD does not set a process id in the pid field in pfloghdr.

FreeBSD 13.1-RELEASE-p6        October 29, 2021        FreeBSD 13.1-RELEASE-p6