pflog —
packet
filter logging interface
device pflog
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];
};
Create a
pflog interface and monitor all packets
logged on it:
# ifconfig pflog1 up
# tcpdump -n -e -ttt -i pflog1
tcpdump(1),
inet(4),
inet6(4),
netintro(4),
pf(4),
ifconfig(8),
pflogd(8)
The
pflog device first appeared in
OpenBSD 3.0.