PFLOG(4) MidnightBSD Kernel Interfaces Manual PFLOG(4)

NAME

pflog — packet filter logging interface

SYNOPSIS

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 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.

MidnightBSD 0.3 December 10, 2001 MidnightBSD 0.3