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 monitored 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, 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[PFLOG_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 rewritten;
sa_family_t naf;
u_int8_t pad[1];
struct pf_addr saddr;
struct pf_addr daddr;
u_int16_t sport;
u_int16_t dport;
};
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.