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MRTG(1) 			     mrtg			       MRTG(1)

       mrtg - What is MRTG ?

       The Multi Router Traffic Grapher (MRTG) is a tool to monitor the traf
       fic load on network links.  MRTG generates HTML pages containing PNG
       images which provide a LIVE visual representation of this traffic.
       Check http://www.stat.ee.ethz.ch/mrtg/ to see what it does.

       Go to
	http://oss.oetiker.ch/mrtg for all the details about mrtg.

	   MRTG works on most UNIX platforms and Windows NT.

	   MRTG is written in Perl and comes with full source.

       Portable SNMP
	   MRTG Uses a highly portable SNMP implementation written entirely in
	   Perl (thanks to Simon Leinen). There is no need to install any
	   external SNMP package.

       SNMPv2c support
	   MRTG can read the new SNMPv2c 64bit counters. No more counter wrap

       Reliable Interface Identification
	   Router interfaces can be identified by IP address, description and
	   ethernet address in addition to the normal interface number.

       Constant size Logfiles
	   MRTGs logfiles do NOT grow thanks to the use of a unique data con
	   solidation algorithm.

       Automatic Configuration
	   MRTG comes with a set of configuration tools which make configura
	   tion and setup very simple.

	   Time critical routines are written in C (thanks to the initiative
	   of Dave Rand my Co-Author).

       GIF free Graphics
	   Graphics are generated directly in PNG format using the GD library
	   by Thomas Boutell.

	   The look of the webpages produced by MRTG is highly configurable.

	   MRTG has built-in hooks for using RRDtool. If you are strapped for
	   performance this may help.

       MRTG consists of a Perl script which uses SNMP to read the traffic
       counters of your routers and a fast C program which logs the traffic
       data and creates beautiful graphs representing the traffic on the moni
       tored network connection. These graphs are embedded into webpages which
       can be viewed from any modern Web-browser.

       In addition to a detailed daily view, MRTG also creates visual repre
       sentations of the traffic seen during the last seven days, the last
       five weeks and the last twelve months. This is possible because MRTG
       keeps a log of all the data it has pulled from the router. This log is
       automatically consolidated so that it does not grow over time, but
       still contains all the relevant data for all the traffic seen over the
       last two years.	This is all performed in an efficient manner.  There
       fore you can monitor 200 or more network links from any halfway decent
       UNIX box.

       MRTG is not limited to monitoring traffic, though.  It is possible to
       monitor any SNMP variable you choose. You can even use an external pro
       gram to gather the data which should be monitored via MRTG. People are
       using MRTG, to monitor things such as System Load, Login Sessions,
       Modem availability and more. MRTG even allows you to accumulate two or
       more data sources into a single graph.

       In 1994 I was working at a site where we had one 64kbit line to the
       outside world. Obviously, everybody was interested in knowing how the
       link was performing. So I wrote a quick hack which created a constantly
       updated graph on the web that showed the traffic load on our Internet
       link. This eventually evolved into a rather configurable Perl script
       called MRTG-1.0 which I released in spring 1995. After a few updates, I
       left my job at DMU to start work at the Swiss Federal Institute of
       Technology. Due to lack of time I had to put MRTG aside. One day in
       January of 1996, I received email from Dave Rand asking if I had any
       ideas why MRTG was so slow. Actually, I did. MRTGs programming was not
       very efficient and it was written entirely in Perl. After a week or so,
       Dave wrote back to me and said he had tried what I had suggested for
       improving MRTGs speed. Since the changes did not help much, he had
       decided to rewrite the time-critical sections of MRTG in C. The code
       was attached to his email. His tool increased the speed of MRTG by a
       factor of 40! This got me out of my MRTG ignorance and I started to
       spend my spare time developing of MRTG-2.

       Soon after MRTG-2 development had begun I started to give beta copies
       to interested parties. In return I got many feature patches, a lot of
       user feedback and bug fixes. The product you are getting now wouldnt
       be in this state if it hadnt been for the great contributions and sup
       port I received from of many people. I would like to take this opportu
       nity to thank them all. (See the files CHANGES for a long list of folk
       people who helped to make MRTG what it is today.)

       Mrtg is also the name of the script you have to run to poll data and
       generate the graphs. Most configuration is set through the configura
       tion file; some command-line options exist all the same.

       --user username	and --group groupname
	   Run as the given user and/or group. (Unix Only)

       --lock-file filename
	   Use an alternate lock-file (the default is to use the configura
	   tion-file appended with "_l").

       --confcache-file filename
	   Use an alternate confcache-file (the default is to use the configu
	   ration-file appended with ".ok")

       --logging filenameeventlog
	   If this is set to writable filename, all output from mrtg (warn
	   ings, debug messages, errors) will go to filename. If you are run
	   ning on Win32 you can specify eventlog instead of a filename which
	   will send all error to the windows event log.

	   NOTE:Note, there is no Message DLL for mrtg. This has the side
	   effect that the windows event logger will display a nice message
	   with every entry in the event log, complaing about the fact that
	   mrtg has no message dll. If any of the Windows folks want to con
	   tribute one, they are welcome.

	   Put MRTG into the background, running as a daemon. This works the
	   same way as the config file option, but the switch is required for
	   proper FHS operation (because /var/run is writable only by root)

	   Configure all mrtg paths to conform to the FHS specification;

	   Only check the cfg file for errors. Do not do anything.

	   Define the name and path of the pid file for mrtg running as a dae

	   Only update the logfile, do not produce graphics or html pages

	   Enable debug options. The argument of the debug option is a comma
	   separated list of debug values:

	    cfg  - watch the config file reading
	    dir  - directory mangeling
	    base - basic program flow
	    tarp - target parser
	    snpo - snmp polling
	    fork - forking view
	    time - some timing info
	    log  - logging of data via rateup or rrdtool



       Learn more about MRTG by going to the mrtg home page on:

       Tobias Oetiker  and many contributors

2.14.7				  2006-09-06			       MRTG(1)

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