Updated: 2022/Sep/29

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IPMON(8)                    System Manager's Manual                   IPMON(8)

       ipmon - monitors /dev/ipl for logged packets

       ipmon [ -abBDFhnpstvxX ] [ -N <device> ] [ -L <facility> ] [ -o [NSI] ]
       [ -O [NSI] ] [ -P <pidfile> ] [ -S <device> ] [ -f <device> ] [
       <filename> ]

       ipmon opens /dev/ipl for reading and awaits data to be saved from the
       packet filter.  The binary data read from the device is reprinted in
       human readable for, however, IP#'s are not mapped back to hostnames,
       nor are ports mapped back to service names.  The output goes to
       standard output by default or a filename, if given on the command line.
       Should the -s option be used, output is instead sent to syslogd(8).
       Messages sent via syslog have the day, month and year removed from the
       message, but the time (including microseconds), as recorded in the log,
       is still included.

       Messages generated by ipmon consist of whitespace separated fields.
       Fields common to all messages are:

       1. The date of packet receipt. This is suppressed when the message is
       sent to syslog.

       2. The time of packet receipt. This is in the form HH:MM:SS.F, for
       hours, minutes seconds, and fractions of a second (which can be several
       digits long).

       3. The name of the interface the packet was processed on, e.g., we1.

       4. The group and rule number of the rule, e.g., @0:17. These can be
       viewed with ipfstat -n.

       5. The action: p for passed, b for blocked,  for a short packet, n did
       not match any rules or L for a log rule.

       6. The addresses.  This is actually three fields: the source address
       and port (separated by a comma), the -> symbol, and the destination
       address and port. E.g.:,80 ->,1722.

       7. PR followed by the protocol name or number, e.g., PR tcp.

       8. len followed by the header length and total length of the packet,
       e.g., len 20 40.

       If the packet is a TCP packet, there will be an additional field
       starting with a hyphen followed by letters corresponding to any flags
       that were set.  See the ipf.conf manual page for a list of letters and
       their flags.

       If the packet is an ICMP packet, there will be two fields at the end,
       the first always being `icmp', and the next being the ICMP message and
       submessage type, separated by a slash, e.g., icmp 3/3 for a port
       unreachable message.

       In order for ipmon to properly work, the kernel option IPFILTER_LOG
       must be turned on in your kernel.  Please see options(4) for more

       ipmon reopens its log file(s) and rereads its configuration file when
       it receives a SIGHUP signal.

       -a     Open all of the device logfiles for reading log entries from.
              All entries are displayed to the same output 'device' (stderr or

       -b     For rules which log the body of a packet, generate hex output
              representing the packet contents after the headers.

       -B <binarylogfilename>
              Enable logging of the raw, unformatted binary data to the
              specified <binarylogfilename> file.  This can be read, later,
              using ipmon with the -f option.

       -D     Cause ipmon to turn itself into a daemon.  Using subshells or
              backgrounding of ipmon is not required to turn it into an orphan
              so it can run indefinitely.

       -f <device>
              specify an alternative device/file from which to read the log
              information for normal IP Filter log records.

       -F     Flush the current packet log buffer.  The number of bytes
              flushed is displayed, even should the result be zero.

       -L <facility>
              Using this option allows you to change the default syslog
              facility that ipmon uses for syslog messages.  The default is

       -n     IP addresses and port numbers will be mapped, where possible,
              back into hostnames and service names.

       -N <device>
              Set the logfile to be opened for reading NAT log records from to

       -o     Specify which log files to actually read data from.  N - NAT
              logfile, S - State logfile, I - normal IP Filter logfile.  The
              -a option is equivalent to using -o NSI.

       -O     Specify which log files you do not wish to read from.  This is
              most sensibly used with the -a.  Letters available as parameters
              to this are the same as for -o.

       -p     Cause the port number in log messages to always be printed as a
              number and never attempt to look it up as from /etc/services,

       -P <pidfile>
              Write the pid of the ipmon process to a file.  By default this
              is //etc/opt/ipf/ipmon.pid (Solaris), /var/run/ipmon.pid (44BSD
              or later) or /etc/ipmon.pid for all others.

       -s     Packet information read in will be sent through syslogd rather
              than saved to a file.  The default facility when compiled and
              installed is local0.  The following levels are used:

              LOG_INFO - packets logged using the "log" keyword as the action
              rather than pass or block.

              LOG_NOTICE - packets logged which are also passed

              LOG_WARNING - packets logged which are also blocked

              LOG_ERR - packets which have been logged and which can be
              considered "short".

       -S <device>
              Set the logfile to be opened for reading state log records from
              to <device>.

       -t     read the input file/device in a manner akin to tail(1).

       -v     show tcp window, ack and sequence fields.

       -x     show the packet data in hex.

       -X     show the log header record data in hex.

       ipmon expects data that it reads to be consistent with how it should be
       saved and will abort if it fails an assertion which detects an anomaly
       in the recorded data.


       ipl(4), ipf(8), ipfstat(8), ipnat(8)

       If you find any, please send email to me at darrenr@pobox.com