PFLOGD(8) | System Manager's Manual | PFLOGD(8) |
pflogd
— packet
filter logging daemon
pflogd |
[-Dx ]
[-d delay]
[-f filename]
[-i interface]
[-s snaplen]
[expression] |
pflogd
is a background daemon which reads
packets logged by pf(4) to a
pflog(4) interface, normally
pflog0, and writes the packets to a logfile
(normally /var/log/pflog) in
tcpdump(8) binary format.
These logs can be reviewed later using the -r
option
of tcpdump(8), hopefully
offline in case there are bugs in the packet parsing code of
tcpdump(8).
pflogd
closes and then re-opens the log
file when it receives SIGHUP
, permitting
newsyslog(8) to rotate
logfiles automatically. SIGALRM
causes
pflogd
to flush the current logfile buffers to the
disk, thus making the most recent logs available. The buffers are also
flushed every delay seconds.
If the log file contains data after a restart or a
SIGHUP
, new logs are appended to the existing file.
If the existing log file was created with a different snaplen,
pflogd
temporarily uses the old snaplen to keep the
log file consistent.
pflogd
tries to preserve the integrity of
the log file against I/O errors. Furthermore, integrity of an existing log
file is verified before appending. If there is an invalid log file or an I/O
error, logging is suspended until a SIGHUP
or a
SIGALRM
is received.
The options are as follows:
-D
pflogd
does not disassociate from
the controlling terminal.-d
delay-f
filename-i
interfacepflogd
will use
pflog0.-s
snaplen-x
<net/if_pflog.h>
. It can
restrict the output to packets logged on a specified interface, a rule
number, a reason, a direction, an IP family or an action.
Log specific TCP packets to a different log file with a large snaplen (useful with a "log all" rule to dump complete sessions):
# pflogd -s 1600 -f suspicious.log port 80 and host evilhost
Log from another pflog(4) interface, excluding specific packets:
# pflogd -i pflog3 -f network3.log "not (tcp and port 23)"
Display binary logs:
# tcpdump -n -e -ttt -r /var/log/pflog
Display the logs in real time (this does not interfere with the
operation of pflogd
):
# tcpdump -n -e -ttt -i pflog0
Display the logs in real time of inbound packets that were blocked on the wi0 interface:
# tcpdump -n -e -ttt -i pflog0 inbound and action block and on wi0
pcap_open_live(3), pf(4), pflog(4), pf.conf(5), newsyslog(8), tcpdump(8)
The pflogd
command appeared in
OpenBSD 3.0.
pflogd
was written by Can
Erkin Acar
<canacar@openbsd.org>.
August 30, 2019 | OpenBSD-7.0 |