mrtg (1)

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NAME

mrtg - What is MRTG ?

DESCRIPTION

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

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

HIGHLIGHTS

Portable

MRTG

works on most

UNIX

platforms and Windows

NT

.

Perl

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 wrapping.

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

MRTG

's logfiles do

NOT

grow thanks to the use of a unique data consolidation algorithm.

Automatic Configuration

MRTG

comes with a set of configuration tools which make configuration and setup very simple.

Performance

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.

Customizability

The look of the webpages produced by

MRTG

is highly configurable.

RRDtool

MRTG

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

DETAILS

consists of a Perl script which uses 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 monitored network connection. These graphs are embedded into webpages which can be viewed from any modern Web-browser.

In addition to a detailed daily view,

also creates visual representations of the traffic seen during the last seven days, the last five weeks and the last twelve months. This is possible because 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. Therefore you can monitor 200 or more network links from any halfway decent box.

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

HISTORY

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 .0 which I released in spring 1995. After a few updates, I left my job at to start work at the Swiss Federal Institute of Technology. Due to lack of time I had to put aside. One day in January of 1996, I received email from Dave Rand asking if I had any ideas why was so slow. Actually, I did. 's 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 's speed. Since the changes did not help much, he had decided to rewrite the time-critical sections of in C. The code was attached to his email. His tool increased the speed of by a factor of 40! This got me out of my ' ignorance' and I started to spend my spare time developing of .

Soon after

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 wouldn't be in this state if it hadn't been for the great contributions and support I received from of many people. I would like to take this opportunity to thank them all. (See the files for a long list of folk people who helped to make what it is today.)

Command-line

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 configuration 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 configuration-file appended with "_l").

--confcache-file filename

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

--logging filename|eventlog

If this is set to writable filename, all output from mrtg (warnings, debug messages, errors) will go to filename. If you are running 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 contribute one, they are welcome.

--daemon

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)

--fhs

Configure all mrtg paths to conform to the

FHS

specification; www.pathname.com/fhs

--check

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

--pid-file=s

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

--log-only

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

--debug=s

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

Example:

 --debug="cfg,snpo"

READ ON

Learn more about by going to the mrtg home page on: oss.oetiker.ch/mrtg

AUTHOR

Tobias Oetiker <tobi@oetiker.ch> and many contributors