NAME
pflogd
—
packet filter logging daemon
SYNOPSIS
pflogd |
[-Dx ]
[-d delay]
[-f filename]
[-i interface]
[-s snaplen]
[expression] |
DESCRIPTION
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
- Debugging mode.
pflogd
does not disassociate from the controlling terminal. -d
delay- Time in seconds to delay between automatic flushes of the file. This may be specified with a value between 5 and 3600 seconds. If not specified, the default is 60 seconds.
-f
filename- Log output filename. Default is /var/log/pflog.
-i
interface- Specifies the pflog(4)
interface to use. By default,
pflogd
will use pflog0. -s
snaplen- Analyze at most the first snaplen bytes of data from each packet rather than the default of 160. The default of 160 is adequate for IP, ICMP, TCP, and UDP headers but may truncate protocol information for other protocols. Other file parsers may desire a higher snaplen.
-x
- Check the integrity of an existing log file, and return.
- expression
- Selects which packets will be dumped, using the regular language of
tcpdump(8). Tcpdump has
been extended to be able to filter on the pfloghdr structure defined in
<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.- ip
- Address family equals IPv4.
- ip6
- Address family equals IPv6.
- ifname kue0
- Interface name equals "kue0".
- on kue0
- Interface name equals "kue0".
- ruleset authpf
- Ruleset name equals "authpf".
- rulenum 10
- Rule number equals 10.
- reason match
- Reason equals match. Also accepts "bad-offset", "fragment", "short", "normalize", "memory", "bad-timestamp", "congestion", "ip-option", "proto-cksum", "state-mismatch", "state-insert", "state-limit", "src-limit", and "synproxy".
- action pass
- Action equals pass. Also accepts "block" and "match".
- inbound
- The direction was inbound.
- outbound
- The direction was outbound.
FILES
- /var/log/pflog
- Default log file.
EXAMPLES
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
SEE ALSO
pcap_open_live(3), pf(4), pflog(4), pf.conf(5), newsyslog(8), tcpdump(8)
HISTORY
The pflogd
command appeared in
OpenBSD 3.0.
AUTHORS
pflogd
was written by Can
Erkin Acar
<canacar@openbsd.org>.