Command Section
IPFWPCAP(8)             FreeBSD System Manager's Manual            IPFWPCAP(8)

     ipfwpcap - copy diverted packets to a file in tcpdump format

     ipfwpcap [-dr] [-b maxbytes] [-p maxpkts] [-P pidfile] portnum dumpfile

     The ipfwpcap utility is used to copy diverted packets to a file in
     tcpdump(1) format.  The interesting packets are diverted by ipfw(8) to a
     port on which ipfwpcap listens.  The packets are then dropped unless -r
     is used.

     The options are as follows:

     -d      Turns on extra debugging messages.

     -r      Writes packets back to the divert(4) socket.

     -rr     Indicates that it is okay to quit if maxbytes or maxpkts are
             reached.  Diverted packets will silently disappear if nothing is
             listening on the divert(4) socket.

     -b maxbytes
             Stop dumping after maxbytes bytes.

     -p maxpkts
             Stop dumping after maxpkt packets.

     -P pidfile
             File to store PID number in.  Default is

     The portnum argument specifies which divert(4) socket port to listen on.
     The dumpfile argument is the path to the file to write captured packets
     to.  Specify `-' to write to stdout.

     The ipfwpcap utility exits 0 on success, and >0 if an error occurs.

           ipfwpcap -r 8091 divt.log &

     Starts ipfwpcap as a background job listening to port 8091 and reflecting
     the packets back to the socket.

           ipfw add 2864 divert 8091 ip from

     Example ipfw(8) rule to divert all packets from to port 8091.
     See ipfw(8) for details.

     tcpdump(1), pcap(3), divert(4), ipfw(8)

     The ipfwpcap utility first appeared in FreeBSD 7.0.

     ipfwpcap was written by P. Kern <[email protected]>.  This manual
     page was written by Niclas Zeising <[email protected]>.

FreeBSD 11.1-RELEASE-p4          May 22, 2006          FreeBSD 11.1-RELEASE-p4
Command Section