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 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
     ⟨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

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

HISTORY

     The pflog device first appeared in OpenBSD 3.0.