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CentOS 2.1AS







reference − MRTG 2.9.5 configuration reference


The runtime behaviour of MRTG is governed by a configuration file. Run of the mill configuration files can be generated with cfgmaker. (Check the cfgmaker manpage). But for more elaborate configurations some hand tuning is required.

This document describes all the configuration options understud by the mrtg software.


MRTG configuration file syntax follows some simple rules:

Keywords must start at the beginning of a line.

Lines which follow a keyword line which do start with a blank are appended to the keyword line

Empty Lines are ignored

Lines starting with a # sign are comments.

You can add other files into the configuration file using

Include: file


 Include: base-options.inc



WorkDir specifies where the logfiles and the webpages should be created.


 WorkDir: /usr/tardis/pub/www/stats/mrtg



HtmlDir specifies the directory where the html (or shtml, but we’ll get on to those later,) lives.

NOTE: Workdir overides the settings for htmldir, imagedir
and logdir


 Htmldir: /www/mrtg/


ImageDir specifies the directory where the images live, they should be under the html directory.


 Imagedir: /www/mrtg/images


LogDir specifies the directory where the logs are stored. This need not be under htmldir directive.


 Logdir: /www/mrtg/logs

Forks ( UNIX only)

An a system that can fork ( UNIX for example) mrtg can fork itself into multiple instances while it is acquiring data via snmp.

For situations with high latency or a great number of devices this will speed things up considerably. It will not make things faster though if you query a single switch sitting next door.

As far as I know NT can not fork so this otion is not available on NT .


 Forks: 4


How many seconds apart should the browser (Netscape) be instructed to reload the page? If this is not defined, the default is 300 seconds (5 minutes).


 Refresh: 600


How often do you call mrtg? The default is 5 minutes. If you call it less often, you should specify it here. This does two things:

the generated HTML page does contain the right information about the calling interval ...

a META header in the generated HTML page will instruct caches about the time to live of this page .....

In this example we tell mrtg that we will be calling it every 10 minutes. If you are calling mrtg every 5 minutes, you can leave this line commented out.


 Interval: 10


With this switch mrtg will generate .meta files for CERN and Apache servers which contain Expiration tags for the html and gif files. The *.meta files will be created in the same directory as the other files, so you will have to set "MetaDir ." and "MetaFiles on" in your apache.conf or .htaccess file for this to work

NOTE: If you are running Apache-1.2 or later, you can use the mod_expire to achieve the same effect ... see the file htaccess.txt


 WriteExpires: Yes


Normally we ask the SNMP device for ’sysUptime’, ’sysName’ properties some do not have these. If you want to avoid getting complaints from mrtg about these missing properties, specivy the nomib2 option.

An example of agents which do not implement base mib2 attributes are Computer Associates − Unicenter TNG Agents. CA relies on using the base OS SNMP agent in addition to its own agents to supplement the management of a system.


 NoMib2: Yes


If you want to keep the mrtg icons in some place other than the working (or imagedir) directory, use the IconDir variable for defining the url to the icons directory.


 IconDir: /mrtgicons/


Load the MIB file(s) specified and make its OIDs available as symbolic names. For better efficiancy, a cache of MIBs is maintained in the WorkDir.


 LoadMIBs: /dept/net/mibs/netapp.mib,/usr/local/lib/ft100m.mib


Switch output format to the selected Language (Check the translate directory to see which languages are supported at the moment. In this directory you can also find instructions on how to create new translations).


 Language: danish


Setting LogFormat to ’rrdtool’ in your mrtg.cfg file enables rrdtool mode. In rrdtool mode, mrtg relies on rrdtool to do its logging. Graphs and html pages will be generated on the fly by the 14all.cgi which can be found in the contrib section together with a short readme ... This feature has been contributed by Rainer.Bawidamann@informatik.uni-ulm.de. Please check his website for more information: http://www.uni-ulm.de/~rbawidam/mrtg-rrd/


 LogFormat: rrdtool


If you are using rrdtool mode and your rrdtool Perl module (RRDs.pm) is not installed in a location where perl can find it on its own, you can use LibAdd to supply an appropriate path.


 LibAdd: /usr/local/rrdtool/lib/perl/


If the rrdtool executable can not be found in the normal ’PATH’, you can use this parameter to add a suitable directory to your path.


 PathAdd: /usr/local/rrdtool/bin/


The RunAsDaemon keyword enables daemon mode operation. The purpose of daemon mode is that MRTG is launched once and not at regular basis by cron as in native mode. This behavior saves computing resourses as loading and parsing of configuration files only hapens once.

Using daemon mode MRTG itself is responible for timing the measurement intervals. Therfore its important to set the Interval keyword to an apropiate value.

Note that using daemon mode MRTG should no longer be started from cron by regular basis as each started process runs forever. Instead MRTG should be started from the command prompt or by a system startup script.

If you want mrtg to run under a particular user and group (it is not recomented to run MRTG as root) then you can use the --user=user_name and --group=group_name options on the mrtg commandline.

 mrtg --user=mrtg_user --group=mrtg_group mrtg.cfg

Also note that in daemon mode restart of the process is required in order to activate changes in the config file.

Under UNIX , the Daemon switch causes mrtg to fork into background after checking its config file. On Windows NT the MRTG process will detach from the console, but because the NT/2000 shell waits for its children you have to use the special start sequence when you launch the program:

 start /b perl mrtg mrtg.cfg

You may have to add path information equal to what you add when you run mrtg from the commandline.



Makes MRTG run as a daemon beginning data collection every 5 minutes


Each monitoring target must be identified by a unique name. This name must be appended to each parameter belonging to the same target. The name will also be used for naming the generated webpages, logfiles and images for this target.


With the Target keyword you tell mrtg what it should monitor. The Target keyword takes arguments in a wide range of formats:

The most basic format is "port:community@router" This will generate a traffic graph for the interface ’port’ of the host ’router’ (dns name or IP address) and it will use the community ’community’ (snmp password) for the snmp query.


 Target[ezwf]: 2:public@wellfleet-fddi.ethz.ch

If your community contains a "@" or a " " these characters mus be escaped with a "\".

 Target[bla]: 2:stu\ pi\@d@router


If you have a fast router you might want to try to poll the ifHC* counters. This feature gets activated by switching to SNMPv2c. Unfortunately not all devices support SNMPv2c yet. If it works, this will prevent your counters from wraping within the 5 minute polling interval. As we now use 64 bit instead of the normal 32 bit.


 Target[ezwf]: 2:public@router1:::::2


Sometimes you are sitting on the wrong side of the link, and you would like to have mrtg report Incoming traffic as outgoing and vice versa. This can be achieved by adding the ’−’ sign in front of the "Target" description. It flips the incoming and outgoing traffic rates.


 Target[ezci]: -1:public@ezci-ether.ethz.ch

Explicit OIDs

You can also explicitly define the OID to query by using the following syntax ’ OID_1&OID_2 :community@router’ The following example will retrieve error counts for input and output on interface 1. MRTG needs to graph two variables, so you need to specify two OID ’s such as temperature and humidity or error input and error output.



MIB Variables

MRTG knows a number of symbolical SNMP variable names. See the file mibhelp.txt for a list of known names. One example are the ifInErrors and ifOutErrors. This means you can specify the above as:


 Target[ezwf]: ifInErrors.1&ifOutErrors.1:public@myrouter

Interface by IP

Sometimes SNMP interface index can change, like when new interfaces are added or removed. This can cause all Target entries in your config file to become wrong by offset, causing MRTG to graphs wrong instances etc. MRTG supports IP address instead of ifindex in target definition. Then MRTG will query snmp device and try to map IP address to current ifindex, You can use IP address in every type of target definition, by adding IP address of the numbered interface after OID and separation char ’/’

Make sure that given IP address is used on your same target router, your same target router, especially when graphing two different OIDs and/or interface split by ’&’ delimiter.

You can tell cfgmaker to generate such references with the option --ifref=ip.


 Target[ezwf]: /
 Target[ezci]: -/
 Target[ezwf]: ifInErrors/

Interface by Description

If you can not use IP addresses you might want to use the interface names. This works similar to the IP address aproach only that the prefix to use is a \ instead of a /

You can tell cfgmaker to generate such references with the option --ifref=descr.


 Target[ezwf]: \My-Interface2:public@wellfleet-fddi.ethz.ch
 Target[ezci]: -\My-Interface2:public@ezci-ether.ethz.ch
 Target[ezwf]: ifInErrors\My-Interface2&ifOutErrors\My-Interface3:public@myrouter

If your description contains a "&", a ":", a "@" or a " " you can include them but you must escape with a backlash:

 Target[ezwf]: \fun\: \ ney\&ddd:public@hello.router

Interface by Name

The only sensible way to reference interfaces of your switches.

You can tell cfgmaker to generate such references with the option --ifref=name.


 Target[ezwf]: #2/11:public@wellfleet-fddi.ethz.ch
 Target[ezci]: -#2/11:public@ezci-ether.ethz.ch
 Target[ezwf]: ifInErrors#3/7&ifOutErrors#3/7:public@myrouter

If your description contains a "&", a ":", a "@" or a " " you can include them but you must escape with a backlash:

 Target[ezwf]: #\: \ fun:public@hello.router

Interface by Ethernet Address

When the SNMP interface index changes, you can key that interface by its ’Physical Address’, sometimes called a ’hard address’, which is the SNMP variable ’ifPhysAddress’. Internally, MRTG matches the Physical Address from the *.cfg file to its current index, and then uses that index for the rest of the session.

You can use the Physical Address in every type of target definition, by adding the Physical Address after the OID and separation char ’!’ (analogous to the IP address option). The Physical address is specified as ’−’ delimited octets, such as "0a-0−f1−5−23−18" (omit the double quotes). Note that some routers use the same Hardware Ethernet Address for all their Interface which prevents unique interface identification. Mrtg will notice such problems and alert you.

You can tell cfgmaker to generate configuration files with hardware ethernet address references by using the option --ifref=eth.


 Target[ezwf]: !0a-0b-0c-0d:public@wellfleet-fddi.ethz.ch
 Target[ezci]: -!0-f-bb-05-71-22:public@ezci-ether.ethz.ch
 Target[ezwf]: ifInErrors!0a-00-10-23-44-51&ifOutErrors!0a-00-10-23-44-51:public@myrouter

Interface by Type

It seems that there are devices that try to defy all monitoring efforts, the interesting interfaces have neither ifName nor a constant ifDescr not to think of a persistant ifIndex. The only way to get a constant mapping is by looking at the interface type, because the interface you are interested in is unique in the device you are looking at ...

You can tell cfgmaker to generate such references with the option --ifref=type.


 Target[ezwf]: %13:public@wellfleet-fddi.ethz.ch
 Target[ezci]: -%13:public@ezci-ether.ethz.ch
 Target[ezwf]: ifInErrors%13&ifOutErrors%14:public@myrouter

Extended Host Name Syntax

In all places where ’’community@router’’ is accepted, you can add additional parameters for the SNMP communication using colon-separated suffixes. The full syntax is as follows:


where the meaning of each parameter is as follows:

the UDP port under which to contact the SNMP agent (default: 161)


initial timeout for SNMP queries, in seconds (default: 2.0)


number of times a timed-out request will be retried (default: 5)


factor by which the timeout is multiplied on every retry (default: 1.0).


for SNMP version if you have a fast router you might want to put a ’2’ here. This will make mrtg try to poll the 64 bit counters. And thus prevent excessive counter wrapping. Not all routers support this though.



A value that equals the default value can be omitted. Trailing colons can be omitted, too.


  Target[ezci]: 1:public@ezci-ether.ethz.ch:9161::4

This would refer to the input/output octet counters for the interface with ifIndex 1 on ezci-ether.ethz.ch, as known by the SNMP agent listening on UDP port 9161. The standard initial timeout (2.0 seconds) is used, but the number of retries is set to four. The backoff value is the default.

External Monitoring Scripts

if you want to monitor something which does not provide data via snmp you can use some external program to do the data gathering.

The external command must return 4 lines of output:
Line 1

current state of the first variable, normally ’incoming bytes count’

Line 2

current state of the second variable, normally ’outgoing bytes count’

Line 3

string (in any human readable format), telling the uptime of the target.

Line 4

string, telling the name of the target.

Depending on the type of data your script returns you might want to use the ’gauge’ or ’absolute’ arguments for the Options keyword.


 Target[ezwf]: ’/usr/local/bin/df2mrtg /dev/dsk/c0t2d0s0’

Note the use of the backticks (’), not apostrophes (’) around the command.

If you want to use a backtick in the command name this can be done but you must escape it with a backslash ...

Multi Target Syntax

You can also use several statements in a mathematical expression. This could be used to aggregate both B channels in an ISDN connection or multiple T1s that are aggregated into a single channel for greater bandwidth. Note the whitespace arround the target definitions.


 Target[ezwf]: 2:public@wellfleetA + 1:public@wellfleetA
              * 4:public@ciscoF


In cases where you calculate the used bandwidth from several interfaces you normaly don’t get the router uptime and router name displayed on the web page.

If these interfaces are on the same router and the uptime and name should be displayed nevertheless you have to specify its community and address again with the RouterUptime keyword.


 Target[kacisco.comp.edu]: 1:public@ + 2:public@
 RouterUptime[kacisco.comp.edu]: public@


The maximum value either of the two variables monitored are allowed to reach. For monitoring router traffic this is normally specified in bytes per second this interface port can carry.

If a number higher than MaxBytes is returned, it is ignored. Also read the section on AbsMax for further info. The MaxBytes value is also used in calculating the Y range for unscaled graphs (see the section on Unscaled).

Since most links are rated in bits per second, you need to divide their maximum bandwidth (in bits) by eight (8) in order to get bytes per second. This is very important to make your unscaled graphs display realistic information. T1 = 193000, 56K = 7000, Ethernet = 1250000. The MaxBytes value will be used by mrtg to decide whether it got a valid response from the router.

If you need two different MaxBytes values for the two monitored variables, you can use MaxBytes1 and MaxBytes2 instead of MaxBytes.


 MaxBytes[ezwf]: 1250000


Same as MaxBytes, for variable 1.


Same as MaxBytes, for variable 2.


Title for the HTML page which gets generated for the graph.


 Title[ezwf]: Traffic Analysis for Our Nice Company


Things to add to the top of the generated HTML page. Note that you can have several lines of text as long as the first column is empty.

Note that the continuation lines will all end up on the same line in the html page. If you want linebreaks in the generated html use the ’\n’ sequence.


 PageTop[ezwf]: <H1>Traffic Analysis for ETZ C95.1</H1>
   Our Campus Backbone runs over an FDDI line\n
   with a maximum transfer rate of 12.5 megabytes per



Things to add to the bottom of the generated HTML page. Note that you can have several lines of text as long as the first column is empty.

Note that the continuation lines will all end up on the same line in the html page. If you want linebreaks in the generated html use the ’\n’ sequence.

The material will be added just before the </BODY> tag:


 PageFoot[ezwf]: Contact <A HREF="mailto:peter@x.yz">Peter</A>
  if you have questions regarding this page


Use this tag like the PageTop header, but its contents will be added between </TITLE> and </HEAD>.


 AddHead[ezwf]: <link rev="made" href="mailto:mrtg@blabla.edu">


BodyTag lets you supply your very own <body ...> tag for the generated webpages.


 BodyTag[ezwf]: <BODY LEFTMARGIN="1" TOPMARGIN="1"


If you are monitoring a link which can handle more traffic than the MaxBytes value. Eg, a line which uses compression or some frame relay link, you can use the AbsMax keyword to give the absolute maximum value ever to be reached. We need to know this in order to sort out unrealistic values returned by the routers. If you do not set AbsMax, rateup will ignore values higher than MaxBytes.


 AbsMax[ezwf]: 2500000


By default each graph is scaled vertically to make the actual data visible even when it is much lower than MaxBytes. With the Unscaled variable you can suppress this. It’s argument is a string, containing one letter for each graph you don’t want to be scaled: d=day w=week m=month y=year. In the example scaling for the yearly and the monthly graph are suppressed.


 Unscaled[ezwf]: ym


By default the graphs only contain the average values of the monitored variables − normally the transfer rates for incoming and outgoing traffic. The following option instructs mrtg to display the peak 5 minute values in the [w]eekly, [m]onthly and [y]early graph. In the example we define the monthly and the yearly graph to contain peak as well as average values.


 WithPeak[ezwf]: ym


By default mrtg produces 4 graphs. With this option you can suppress the generation of selected graphs. The option value syntax is analogous to the above two options. In this example we suppress the yearly graph as it is quite empty in the beginning.


 Suppress[ezwf]: y


By default, mrtg creates .html files. Use this option to tell mrtg to use a different extension. For example you could set the extension to php3, then you will be able to enclose PHP tags into the output (usefull for getting a router name out of a database).


 Extension[ezwf]: phtml


By default, mrtg puts all the files that it generates for each target (the GIFs, the HTML page, the log file, etc.) in WorkDir.

If the Directory option is specified, the files are instead put into a directory under WorkDir or Log-, Image- and HtmlDir). (For example the Directory option below would cause all the files for a target ezwf to be put into directory /usr/tardis/pub/www/stats/mrtg/ezwf/ .)

The directory must already exist; mrtg will not create it.


 WorkDir: /usr/tardis/pub/www/stats/mrtg
 Directory[ezwf]: ezwf

NOTE: the Directory option must always be ’relative’ or bad things will happen.

XSize and YSize

By default mrtgs graphs are 100 by 400 pixels wide (plus some more for the labels. In the example we get almost square graphs ...

Note: XSize must be between 20 and 600; YSize must be larger than 20


 XSize[ezwf]: 300
 YSize[ezwf]: 300

XZoom and YZoom

If you want your graphs to have larger pixels, you can "Zoom" them.


 XZoom[ezwf]: 2.0
 YZoom[ezwf]: 2.0

XScale and YScale

If you want your graphs to be actually scaled use XScale and YScale. (Beware while this works, the results look ugly (to be frank) so if someone wants to fix this: patches are welcome.


 XScale[ezwf]: 1.5
 YScale[ezwf]: 1.5

YTics and YTicsFactor

If you want to show more than 4 lines per graph, use YTics. If you want to scale the value used for the YLegend of these tics, use YTicsFactor. The default value for YTics is 4 and the default value for YTicsFactor is 1.0 .


  Suppose you get values ranging from 0 to 700.
  You want to plot 7 lines and want to show
  0, 1, 2, 3, 4, 5, 6, 7 instead of 0, 100, 200,
  300, 400, 500, 600, 700.  You should write then:
  YTics[ezwf]: 7
  YTicsFactor[ezwf]: 0.01


If you want to multiply all numbers shown below the graph with a constant factor, use this directive to define it ..


  Factor[as400]: 4096


Change the default step from 5 * 60 seconds to something else (I have not tested this well ...)


 Step[ezwf]: 60


The Options Keyword allows you to set some boolean switches:

The graph grows to the left by default. This option flips the direction of growth causing the current time to be at the right edge of the graph and the history values to the left of it.


All the monitored variable values are multiplied by 8 (i.e. shown in bits instead of bytes) ... looks much more impressive :−) It also affects the ’factory default’ labeling and units for the given target.


All the monitored variable values are multiplied by 60 (i.e. shown in units per minute instead of units per second) in case of small values more accurate graphs are displayed. It also affects the ’factory default’ labeling and units for the given target.


All the monitored variable values are multiplied by 3600 (i.e. shown in units per hour instead of units per second) in case of small values more accurate graphs are displayed. It also affects the ’factory default’ labeling and units for the given target.


Suppress the information about uptime and device name in the generated webpage.


Don’t print usage percentages


make the background of the generated gifs transparent ...


Print summary lines below graph as integers without comma


The relative percentage of IN-traffic to OUT-traffic is calculated and displayed in the graph as an additional line. Note: Only a fixed scale is available (from 0 to 100%). Therefore for IN-traffic greater than OUT-traffic also 100% is displayed. If you suspect that your IN-traffic is not always less than or equal to your OUT-traffic you are urged to not use this options. Note: If you use this option in combination with the Colours options, a fifth colour-name colour-value pair is required there.


Treat the values gathered from target as ’current status’ measurements and not as ever incrementing counters. This would be useful to monitor things like disk space, processor load, temperature, and the like ...

In the absence of ’gauge’ or ’absolute’ options, MRTG treats variable as a counter and calculates the difference between the current and the previous value and divides that by the elapsed time between the last two readings to get the value to be plotted.


This is for counter type data sources which reset their value when they are read. This means that rateup does not have to build the difference between the current and the last value read from the data source. The value obtained is still divided by the elapsed time between the current and the last reading, which makes it different from the ’gauge’ option. Useful for external data gatherers.


Log unknown data as zero instead of the default behaviour of repeating the last value seen. Be careful with this, often a flat line in the graph is much more obvious than a line at 0.


Normally we ignore all values which are zero when calculating the average transfer rate on a line. If this is not desirable use this option.


 Options[ezwf]: growright, bits


Use this option to change the multiplier value for building prefixes. Defaultvalue is 1000. This tag is for the special case that 1kB = 1024B, 1MB = 1024kB and so far.


 kilo[ezwf]: 1024


Change the default multiplier prefixes (,k,M,G,T,P). In the tag ShortLegend define only the basic units. Format: Comma seperated list of prefixed. Two consecutive commas or a comma at start or end of the line gives no prefix on this item. Note: If you do not want prefixes, then leave this line blank.

Example: velocity in nm/s (nanometers per second) displayed in nm/h.

 ShortLegend[ezwf]: m/min
 kMG[ezwf]: n,u,m,,k,M,G,T,P
 options[ezwf]: perhour


The Colours tag allows you to override the default colour scheme. Note: All 4 of the required colours must be specified here. The colour name (’Colourx’ below) is the legend name displayed, while the RGB value is the real colour used for the display, both on the graph and in the html doc.

Format is: Colour1#RRGGBB,Colour2#RRGGBB,Colour3#RRGGBB,Colour4#RRGGBB

Important: If you use the dorelpercent options tag a fifth colour name colour value pair is required: Colour1#RRGGBB,Colour2#RRGGBB,Colour3#RRGGBB,Colour4#RRGGBB,Colour5#RRGGBB

First variable (normally Input) on default graph


Second variable (normally Output) on default graph


Max first variable (input)


Max second variable (output)


2 digit hex values for Red, Green and Blue


 Colours[ezwf]: GREEN#00eb0c,BLUE#1000ff,DARK GREEN#006600,VIOLET#ff00ff


With the Background tag you can configure the background colour of the generated HTML page


 Background[ezwf]: #a0a0a0a

YLegend, ShortLegend, Legend[1234]

The following keywords allow you to override the text displayed for the various legends of the graph and in the HTML document

The Y-axis label of the graph. Note that a text which is too long to fit in the graph will be silently ignored.


The units string (default ’b/s’) used for Max, Average and Current


The strings for the colour legend


  YLegend[ezwf]: Bits per Second
  ShortLegend[ezwf]: b/s
  Legend1[ezwf]: Incoming Traffic in Bits per Second
  Legend2[ezwf]: Outgoing Traffic in Bits per Second
  Legend3[ezwf]: Maximal 5 Minute Incoming Traffic
  Legend4[ezwf]: Maximal 5 Minute Outgoing Traffic
  LegendI[ezwf]: &nbsp;In:
  LegendO[ezwf]: &nbsp;Out:

Note, if LegendI or LegendO are set to an empty string with


The corresponding line below the graph will not be printed at all.


If you live in an international world, you might want to generate the graphs in different timezones. This is set in the TZ variable. Under certain operating systems like Solaris, this will provoke the localtime call to give the time in the selected timezone ...


 Timezone[ezwf]: Japan

The Timezone is the standard Solaris timezone, ie Japan, Hongkong, GMT , GMT+1 etc etc.


By default, mrtg (actually rateup) uses the strftime(3) ’%W’ option to format week numbers in the monthly graphs. The exact semantics of this format option vary between systems. If you find that the week numbers are wrong, and your system’s strftime(3) routine supports it, you can try another format option. The POSIX ’%V’ option seems to correspond to a widely used week numbering convention. The week format character should be specified as a single letter; either W, V, or U.


 Weekformat[ezwf]: V


When calling external scrits from withing your cfg file (Threshold or script targets) you might want to pass some data on to the script. This can be done with the SetEnv configuration option ... it takes a series of environment variable assignments. Note that the quotes are mandatory.


 SetEnv[myrouter]:  EMAIL="contact_email@someplace.net"


Through its threshold checking functionality mrtg is able to detect threshold problems for the various targets and can call external scripts to handle those problems (send email or a page to an administrator).

Threshold checking is configured through the following parameters:

ThreshDir ( GLOBAL )

If you want to be able to detect when a parameter is OK again (back within threshold), you must define this directory. Temporary files will be stored here between runnings to indicate which parameters had threshold problems on the previous running.

ThreshMinI ( PER TARGET )

This is the minimum acceptable value for the Input (first) parameter. If the parameter falls below this value, the program specified in ThreshProgI will be run. If the value ends in ’%’ then the threshold is defined relative to MaxBytes.

ThreshMaxI ( PER TARGET )

This is the maximum acceptable value for the Input (first) parameter. If the parameter falls above this value, the program specified in ThreshProgI will be run. If the value ends in ’%’ then the threshold is defined relative to MaxBytes.

ThreshDesc ( PER TARGET )

Its value will be assigned to the environment variable THRESH_DESC before any of the programs mentioned below are called. The programms can use the value of this variable to produce more userfriendly output.

ThreshProgI ( PER TARGET )

This defines a program to be run if ThreshMinI or ThreshMaxI is broken. (It currently passes 3 arguments: the $router variable, the threshold value broken, and the current parameter value. This can be changed as required.)

ThreshProgOKI ( PER TARGET )

This defines a program to be run if the parameter is currently OK (based on ThreshMinI and ThreshMaxI), but wasn’t OK on the previous running -- based on the files found in ThreshDir.

ThreshMinO, ThreshMaxO, ThreshProgO, and ThreshProgOKO

They work the same as their *I counterparts, except on the Output (second) parameter.


Pre- and Postfix

To save yourself some typing you can define a target called ’^’. The text of every Keyword you define for this target will be PREPENDED to the corresponding Keyword of all the targets defined below this line. The same goes for a Target called ’$’ but its text will be APPENDED .

Note that a space is inserted between the prepended text and the Keyword value, as well as between the Keyword value and the appended text. This works well for text-valued Keywords, but is not very useful for other Keywords. See the "default" target description below.

The example will make mrtg use a common header and a common contact person in all the pages generated from targets defined later in this file.


 PageTop[^]: <H1>NoWhere Unis Traffic Stats</H1><HR>
 PageTop[$]: Contact Peter Norton if you have any questions<HR>

To remove the prepend/append value, specify an empty value, e.g.:


NOTE: With PREPEND and APPEND there is normally a space inserted between the local value and the PRE- or APPEND value. Sometimes this is not desirable. You can use the NoSpaceChar config option to define a character which can be mentioned at the end of a $ or ^ definition in order to supress the space.


  NoSpaceChar: ~
  Target[a]: a.tolna.net
  Target[b]: b.tolna.net
  Target[c]: c.tolna.net
  Target[d]: d.tolna.net

Default Values

The target name ’_’ specifies a default value for that Keyword. In the absence of explicit Keyword value, the prepended and the appended keyword value, the default value will be used.


 YSize[_]: 150
 Options[_]: growright,bits,nopercent
 WithPeak[_]: ymw
 Suppress[_]: y
 MaxBytes[_]: 1250000

To remove the default value and return to the ’factory default’, specify an empty value, e.g.:


There can be several instances of setting the default/prepend/append values in the configuration file. The later setting replaces the previous one for the rest of the configuration file. The default/prepend/append values used for a given keyword/target pair are the ones that were in effect at the point in the configuration file where the target was mentioned for the first time.


 MaxBytes[_]: 1250000
 Target[myrouter.somplace.edu.2]: 2:public@myrouter.somplace.edu
 MaxBytes[_]: 8000
 Title[myrouter.somplace.edu.2]: Traffic Analysis for myrouter.somplace.edu IF 2

The default MaxBytes for the target myrouter.somplace.edu.2 in the above example will be 1250000, which was in effect where the target name myrouter.somplace.edu.2 first appeared in the config file.


Minimal mrtg.cfg

 WorkDir: /usr/tardis/pub/www/stats/mrtg
 Target[r1]: 2:public@myrouter.somplace.edu
 MaxBytes[r1]: 8000
 Title[r1]: Traffic Analysis ISDN
 PageTop[r1]: <H1>Stats for our ISDN Line</H1>

Cfg for several Routers.

 WorkDir: /usr/tardis/pub/www/stats/mrtg
 Title[^]: Traffic Analysis for
 PageTop[^]: <H1>Stats for
 PageTop[$]: Contact The Chief if you notice anybody<HR>
 MaxBytes[_]: 8000
 Options[_]: growright
 Title[isdn]: our ISDN Line
 PageTop[isdn]: our ISDN Line</H1>
 Target[isdn]: 2:public@router.somplace.edu
 Title[backb]: our Campus Backbone
 PageTop[backb]: our Campus Backbone</H1>
 Target[backb]: 1:public@router.somplace.edu
 MaxBytes[backb]: 1250000
 # the following line removes the default prepend value
 # defined above

 Title[isdn2]: Traffic for the Backup ISDN Line
 PageTop[isdn2]: our ISDN Line</H1>
 Target[isdn2]: 3:public@router.somplace.edu


Tobias Oetiker <oetiker@ee.ethz.ch> and many contributors