.\" Copyright (c) 2006 Niclas Zeising
.\" All rights reserved.
.\"
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.\" modification, are permitted provided that the following conditions
.\" are met:
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.\" $FreeBSD: /repoman/r/ncvs/src/usr.sbin/ipfwpcap/ipfwpcap.8,v 1.3 2006/09/30 19:07:03 ru Exp $
.\"
.Dd Dec 20, 2006
.Dt IPFWPCAP 8
.Os
.Sh NAME
.Nm ipfwpcap
.Nd "copy diverted packets to a file in tcpdump format"
.Sh SYNOPSIS
.Nm
.Op Fl dz
.Op Fl r | rr
.Op Fl i Ar flush_interval
.Op Fl b Ar maxbytes
.Op Fl p Ar maxpkts
.Op Fl P Ar pidfile
.Ar portnum
.Ar dumpfile
.Sh DESCRIPTION
The
.Nm
utility is used to copy diverted packets to a file in
.Xr tcpdump 1
format.
The interesting packets are diverted by
.Xr ipfw 8
to a port on which
.Nm
daemon listens.
The packets are then dropped unless
.Fl r
is used.
.Pp
.Nm
closes and then re-opens the dump file when it receives
.Dv SIGHUP ,
permitting
.Xr newsyslog 8
to rotate dump logfiles automatically.
Note that already existing file will be truncated on open or re-open.
Receiving
.Dv 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 flush_interval
seconds.
.Pp
The options are as follows:
.Bl -tag -width indent
.It Fl d
Turns on debugging messages and prevents
.Nm
from making itself a background daemon.
.It Fl r
Writes packets back to the
.Xr divert 4
socket.
This option can be used to reflect packets back to
.Xr ipfw 8
if you for some reasons want to use
.Dq divert
rule action instead of usually more suitable
.Dq tee .
.It Fl rr
Indicates that it is okay to quit if
.Ar maxbytes
or
.Ar maxpkts
are reached.
Diverted packets will silently disappear if nothing is listening on the
.Xr divert 4
socket.
.It Fl b Ar maxbytes
Stop dumping after
.Ar maxbytes
bytes.
Note that size of resulting
.Ar dumpfile
will be greater than
.Ar maxbytes
because
.Xr pcap 3
stores additional headers for each packet in the file.
.It Fl i Ar flush_interval
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 p Ar maxpkts
Stop dumping after
.Ar maxpkt
packets.
.It Fl P Ar pidfile
File to store PID number in.
Default is
.Pa /var/run/ipwfpcap. Ns Ao Ar portnum Ac Ns Pa .pid .
.It Fl z
Reset byte and packet counters to zero after each reopening of the
.Ar dumpfile .
.El
.Pp
The
.Ar portnum
argument specifies which
.Xr divert 4
socket port to listen on.
The
.Ar dumpfile
argument is the path to the file to write captured packets to.
Specify
.Sq Fl
to write to stdout.
.Sh EXIT STATUS
.Ex -std
.Sh EXAMPLES
.Dl "ipfwpcap -r 8091 divt.log"
.Pp
Starts
.Nm
as a background job listening to port 8091 and reflecting the packets
back to the socket.
.Pp
.Dl "ipfw add 2864 divert 8091 ip from 192.0.2.101"
.Pp
Example
.Xr ipfw 8
rule to divert all packets from 192.0.2.101 to port 8091.
See
.Xr ipfw 8
for details.
.Sh SEE ALSO
.Xr tcpdump 1 ,
.Xr pcap 3 ,
.Xr divert 4 ,
.Xr ipfw 8 ,
.Xr pflogd 8
.Sh HISTORY
The
.Nm
utility first appeared in
.Fx 6.3 .
.Sh AUTHORS
.An -nosplit
.Nm
was written by
.An P. Kern Aq pkern@cns.utoronto.ca .
This manual page was written by
.An Niclas Zeising Aq lothrandil@n00b.apagnu.se .