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NIFMON(8)		  BSD System Manager's Manual		     NIFMON(8)

     nifmon -- display network interface status, statistics and	data

     nifmon [-b] [-e expr] [-i if] [-r tty] [-t	term]

     nifmon is a curses	application which displays counters and	statistics of
     one particular network interface in one part of the screen	and a stripped
     down tcpdump(8) output for	this interface in the other part of the

     It	is intended to be run in background on an unused syscons(4) or pcvt(4)
     virtual terminal to monitor a tun(4) interface used with ppp(8) with an
     ADSL line but can also be started as a normal program to monitor any
     other network interface.

     The following options are available:

     -b	     selects background	mode of	operation, note	that specifying	op-
	     tions -t and -r is	mandatory with this mode.

     -e	     specify a filter expression to be used with tcpdump.

     -i	     select the	interface to be	monitored (default is lo0).

     -r	     select the	device file of a virtual terminal to which output is

     -t	     specify the terminal type (i.e. vt220, cons25, pcvt25) for	the
	     terminal selected with the	-r option.

     Following is a description	of the various displayed fields	from top to
     bottom: In	the first line the interfaces IP address, hostname and either
     the destination address (for point-to-point links)	or broadcast address
     is	displayed followed by a	line of	the last administrative	change time
     and the previous administrative change time and the hour, minutes and
     seconds how long these lasted (i wanted to	know how long the dynamic IP
     addresses i got from my provider were in effect).

     Then come two lines with the number of bytes in and out and the number of
     packets in	and out	for this interface.

     After that	you get	statistics: the	number of bytes	and packets in and out
     for the last second, minute and hour.

     In	the lower half of the screen an	(adjusted and mangled) output of tcp-
     dump running on that interface can	be seen	(i just	wanted to get a	very
     rough idea	what is	happening on that interface). A	filter expression
     (i.e. "ip") for this tcpdump can be specified on the commandline using
     the -e switch.

     To	get the	most needed information	available from tcpdump,	its output is
     modified as follows: only lines starting with a timestamp are displayed,
     the date is removed from the timestamp, the own hostname is removed and
     the strings [tcp sum ok] and [udp sum ok] are removed.


     The whole thing started as	a hack,	a fact which can be seen at many
     places in the source. The pipe interface to run tcpdump is	a bit strange,
     when nifmon is killed or abnormally terminated, the forked	tcpdump	will
     have to be	terminated manually. Suggestions, hints	and patches welcome.

     The command:

	   nifmon -b -itun1 -r/dev/ttyv2 -tpcvt25h

     monitors interface	tun1 in	background mode	on virtual terminal /dev/ttyv2
     with a terminal type of pcvt25h (for the pcvt driver).

     The nifmon	utility	and this manpage were written by Hellmuth Michaelis

BSD				August 19, 2001				   BSD


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