.\"	$OpenBSD: pflogd.8,v 1.16 2002/11/09 00:57:20 fgsch Exp $
.\"
.\" Copyright (c) 2001 Can Erkin Acar.  All rights reserved.
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.Dd July 9, 2001
.Dt PFLOGD 8
.Os
.Sh NAME
.Nm pflogd
.Nd packet filter logging daemon
.Sh SYNOPSIS
.Nm pflogd
.Op Fl D
.Op Fl d Ar delay
.Op Fl f Ar filename
.Op Fl s Ar snaplen
.Op Ar expression
.Sh DESCRIPTION
.Nm
is a background daemon which reads packets logged by
.Xr pf 4
to the packet logging interface
.Pa pflog0
and writes the packets to a logfile (normally
.Pa /var/log/pflog )
in
.Xr tcpdump 8
binary format.
These logs can be reviewed later using the
.Ar -r
option of
.Xr tcpdump 8 ,
hopefully offline in case there are bugs in the packet parsing code of
.Xr tcpdump 8 .
.Pp
.Nm
closes and then re-opens the log file when it receives
.Va SIGHUP ,
permitting
.Xr newsyslog 8
to rotate logfiles automatically.
.Va SIGALRM
causes
.Nm
to flush the current logfile buffers to the disk, thus making the most
recent logs available.
The buffers are also flushed every
.Ar delay
seconds.
.Pp
If the log file contains data after a restart or a
.Va SIGHUP ,
new logs are appended to the existing file.
If the existing log file was created with a different snaplen,
.Nm
temporarily uses the old snaplen to keep the log file consistent.
.Pp
The options are as follows:
.Bl -tag -width Ds
.It Fl d Ar 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.
.It Fl D
Debugging mode.
.Nm
does not disassociate from the controlling terminal.
.It Fl f Ar filename
Log output filename.
Default is
.Pa /var/log/pflog .
.It Fl s Ar snaplen
Analyze at most the first
.Ar snaplen
bytes of data from each packet rather than the default of 96.
The default of 96 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.
.It Ar expression
selects which packets will be dumped, using the regular language of
.Xr tcpdump 8 .
.El
.Sh EXAMPLES
Log specific tcp packets to a different log file with a large snaplen
(useful with a log-all rule to dump complete sessions)
.Bd -literal -offset indent
# pflogd -s 1600 -f suspicious.log port 80 and host evilhost
.Ed
.Pp
Display binary logs:
.Bd -literal -offset indent
# tcpdump -n -e -ttt -r /var/log/pflog
.Ed
.Pp
Display the logs in real time (this does not interfere with the
operation of pflogd):
.Bd -literal -offset indent
# tcpdump -n -e -ttt -i pflog0
.Ed
.Pp
Tcpdump has been extended to to be able to filter on the pfloghdr
structure defined in net/if_pflog.h.  Tcpdump can restrict the output
to packets logged on a specified interface, a rule number, a reason,
a direction, an ip family or an action.
.Bl -tag -width "reason match " -compact
.It ip
Address family equals IPv4.
.It ip6
Address family equals IPv6.
.It ifname kue0
Interface name equals "kue0"
.It on kue0
Interface name equals "kue0"
.It rulenum 10
Rule number equals 10.
.It reason match
Reason equals match.  Also accepts "bad-offset", "fragment", "short",
"normalize" and "memory".
.It action pass
Action equals pass.  Also accepts "block".
.It inbound
The direction was inbound.
.It outbound
The direction was outbound.
.El
.Pp
Display the logs in real time of inbound packets that were blocked on
the wi0 interface:
.Bd -literal -offset indent
# tcpdump -n -e -ttt -i pflog0 inbound and action block and on wi0
.Ed
.Sh FILES
.Bl -tag -width /var/run/pflogd.pid -compact
.It Pa /var/run/pflogd.pid
process ID of current
.It Pa /var/log/pflog
Default log file
.El
.Sh SEE ALSO
.Xr pcap 3 ,
.Xr pf 4 ,
.Xr pflog 4 ,
.Xr pf.conf 5 ,
.Xr newsyslog 8 ,
.Xr tcpdump 8
.Sh AUTHORS
Can Erkin Acar
.Sh HISTORY
The
.Nm
command appeared in
.Ox 3.0 .