NIFMON(8) BSD System Manager's Manual NIFMON(8)NAMEnifmon — display network interface status, statistics and data
SYNOPSISnifmon [-b] [-e expr] [-i if] [-r tty] [-t term]
DESCRIPTIONnifmon 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
screen.
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
options -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
redirected.
-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.
FILES
/var/run/nifmon-<interface>.pid
BUGS
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.
EXAMPLES
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).
AUTHORS
The nifmon utility and this manpage were written by Hellmuth Michaelis
⟨hm@freebsd.org⟩.
BSD August 19, 2001 BSD
