.\" Copyright (c) 2006 Niclas Zeising <zeising@FreeBSD.org>
.\" All rights reserved.
.\"
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.\" $FreeBSD$
.\"
.Dd May 22, 2006
.Dt IPFWPCAP 8
.Os
.Sh NAME
.Nm ipfwpcap
.Nd "copy diverted packets to a file in tcpdump format"
.Sh SYNOPSIS
.Nm
.Op Fl dr
.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
listens.
The packets are then dropped unless
.Fl r
is used.
.Pp
The options are as follows:
.Bl -tag -width indent
.It Fl d
Turns on extra debugging messages.
.It Fl r
Writes packets back to the
.Xr divert 4
socket.
.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.
.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.portnr.pid .
.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
.Sh HISTORY
The
.Nm
utility first appeared in
.Fx 7.0 .
.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 zeising@FreeBSD.org .