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MRTG-REFERENCE(1) mrtg MRTG-REFERENCE(1)
NAME
mrtg-reference - MRTG 2.16.4 configuration reference
OVERVIEW
The runtime behaviour of MRTG is governed by a configuration file. Run-of-the-mill configuration files can be generated
with cfgmaker. (Check cfgmaker). But for more elaborate configurations some hand-tuning is required.
This document describes all the configuration options understood by the mrtg software.
SYNTAX
MRTG configuration file syntax follows some simple rules:
o Keywords must start at the beginning of a line.
o Lines which follow a keyword line which start with a blank are appended to the keyword line
o Empty Lines are ignored
o Lines starting with a # sign are comments.
o You can add other files into the configuration file using
Include: file
Example:
Include: base-options.inc
If included files are specified with relative paths, both the current working directory and the directory containing
the main config file will be searched for the files.
GLOBAL KEYWORDS
WorkDir
WorkDir specifies where the logfiles and the webpages should be created.
Example:
WorkDir: /usr/tardis/pub/www/stats/mrtg
OPTIONAL GLOBAL KEYWORDS
HtmlDir
HtmlDir specifies the directory where the html (or shtml, but we'll get on to those later) lives.
NOTE: Workdir overrides the settings for htmldir, imagedir and logdir.
Example:
Htmldir: /www/mrtg/
ImageDir
ImageDir specifies the directory where the images live. They should be under the html directory.
Example:
Imagedir: /www/mrtg/images
LogDir
LogDir specifies the directory where the logs are stored. This need not be under htmldir directive.
Example:
Logdir: /www/mrtg/logs
Forks (UNIX only)
With system that supports 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 option is not available on NT.
Example:
Forks: 4
EnableIPv6
When set to yes, IPv6 support is enabled if the required libraries are present (see the mrtg-ipv6 manpage). When IPv6 is
enabled, mrtg can talk to routers using SNMP over IPv6 and targets may be specified by their numeric IPv6 addresses as
well as by hostname or IPv4 address.
If IPv6 is enabled and the target is a hostname, mrtg will try to resolve the hostname to an IPv6 address and, if this
fails, to an IPv4 address. Note that mrtg will only use IPv4 if you specify an IPv4 address or a hostname with no
corresponding IPv6 address; it will not fall back to IPv4 if it simply fails to communicate with the target using IPv6.
This is by design.
Note that many routers do not currently support SNMP over IPv6. Use the IPv4Only per target option for these routers.
IPv6 is disabled by default.
Example:
EnableIPv6: Yes
EnableSnmpV3
When set to yes, uses the Net::SNMP module instead of the SNMP_SESSION module for generating snmp queries. This allows
the use of SNMPv3 if other snmpv3 parameters are set.
SNMPv3 is disabled by default.
Example:
EnableSnmpV3: yes
Refresh
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).
Example:
Refresh: 600
Interval
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:
o The generated HTML page contains the right information about the calling interval ...
o 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.
Example:
Interval: 10
Note that unless you are using rrdtool you can not set Interval to less than 5 minutes. If you are using rrdtool you can
set interval in the format
Interval: MM[:SS]
Down to 1 second. Note though, setting the Interval for an rrdtool/mrtg setup will influence the initial creation of the
database. If you change the interval later, all existing databases will remain at the resolution they were initially
created with. Also note that you must make sure that your mrtg-rrd Web-frontend can deal with this kind of Interval
setting.
MaxAge
MRTG relies heavily on the real time clock of your computer. If the time is set to a wrong value, especially if it is
advanced far into the future, this will cause mrtg to expire lots of supposedly old data from the log files.
To prevent this, you can add a 'reasonability' check by specifying a maximum age for log files. If a file seems to be
older, mrtg will not touch it but complain instead, giving you a chance to investigate the cause.
Example:
MaxAge: 7200
The example above will make mrtg refuse to update log files older than 2 hours (7200 seconds).
WriteExpires
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
Example:
WriteExpires: Yes
NoMib2
Normally we ask the SNMP device for 'sysUptime' and 'sysName' properties. Some do not have these. If you want to avoid
getting complaints from mrtg about these missing properties, specify 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.
Example:
NoMib2: Yes
SingleRequest
Some SNMP implementations can not deal with requests asking for multiple snmp variables in one go. Set this in your cfg
file to force mrtg to only ask for one variable per request.
Examples
SingleRequest: Yes
SnmpOptions
Apart from the per target timeout options, you can also configure the behaviour of the snmpget process on a more profound
level. SnmpOptions accepts a hash of options. The following options are currently supported:
timeout => $default_timeout,
retries => $default_retries,
backoff => $default_backoff,
default_max_repetitions => $max_repetitions,
use_16bit_request_ids => 1,
lenient_source_port_matching => 0,
lenient_source_address_matching => 1
The values behind the options indicate the current default value. Note that these settings OVERRIDE the per target
timeout settings.
A per-target SnmpOptions[] keyword will override the global settings. That keyword is primarily for SNMPv3.
The 16bit request ids are the only way to query the broken SNMP implementation of SMC Barricade routers.
Example:
SnmpOptions: retries => 2, only_ip_address_matching => 0
Note that AS/400 snmp seems to be broken in a way which prevents mrtg from working with it unless
SnmpOptions: lenient_source_port_matching => 1
is set.
IconDir
If you want to keep the mrtg icons in someplace other than the working (or imagedir) directory, use the IconDir variable
for defining the url of the icons directory.
Example:
IconDir: /mrtgicons/
LoadMIBs
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.
Example:
LoadMIBs: /dept/net/mibs/netapp.mib,/usr/local/lib/ft100m.mib
Language
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).
Currently the following laguages are supported:
big5 brazilian bulgarian catalan chinese croatian czech danish dutch eucjp french galician gb gb2312 german greek
hungarian icelandic indonesia iso2022jp italian korean lithuanian malay norwegian polish portuguese romanian russian
russian1251 serbian slovak slovenian spanish swedish turkish ukrainian
Example:
Language: danish
LogFormat
Setting LogFormat to 'rrdtool' in your mrtg.cfg file enables rrdtool mode. In rrdtool mode, mrtg relies on rrdtool to do
its logging. See mrtg-rrd.
Example:
LogFormat: rrdtool
LibAdd
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.
Example:
LibAdd: /usr/local/rrdtool/lib/perl/
PathAdd
If the rrdtool executable can not be found in the normal "PATH", you can use this keyword to add a suitable directory to
your path.
Example:
PathAdd: /usr/local/rrdtool/bin/
RunAsDaemon
The RunAsDaemon keyword enables daemon mode operation. The purpose of daemon mode is that MRTG is launched once and not
repeatedly (as it is with cron). This behavior saves computing resourses as loading and parsing of configuration files
happens only 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 when using daemon mode MRTG should no longer be started from cron as each new 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 recomended 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 restarting 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 this 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.
Example
RunAsDaemon: Yes
Interval: 5
This makes MRTG run as a daemon beginning data collection every 5 minutes
If you are daemontools and still want to run mrtg as a daemon you can additionally specify
NoDetach: Yes
this will make mrtg run but without detaching it from the terminal.
ConversionCode
Some devices may produce non-numeric values that would nevertheless be useful to graph with MRTG if those values could be
converted to numbers. The ConversionCode keyword specifies the path to a file containing Perl code to perform such
conversions. The code in this file must consist of one or more Perl subroutines. Each subroutine must accept a single
string argument and return a single numeric value. When RRDtool is in use, a decimal value may be returned. When the name
of one of these subroutines is specified in a target definition (see below), MRTG calls it twice for that target, once to
convert the the input value being monitored and a second time to convert the output value. The subroutine must return an
undefined value if the conversion fails. In case of failure, a warning may be posted to the MRTG log file using Perl's
warn function. MRTG imports the subroutines into a separate name space (package MRTGConversion), so the user need not
worry about pollution of MRTG's global name space. MRTG automatically prepends this package declaration to the user-
supplied code.
Example: Suppose a particular OID returns a character string whose length is proportional to the value to be monitored.
To convert this string to a number that can be graphed by MRTG, create a file arbitrarily named "MyConversions.pl"
containing the following code:
# Return the length of the string argument
sub Length2Int {
my $value = shift;
return length( $value );
}
Then include the following global keyword in the MRTG configuration file (assuming that the conversion code file is saved
in the mrtg/bin directory along with mrtg itself):
ConversionCode: MyConversions.pl
This will cause MRTG to include the definition of the subroutine Length2Int in its execution environment. Length2Int can
then be invoked on any target by appending "|Length2Int" to the target definition as follows:
Target[myrouter]: 1.3.6.1.4.1.999.1&1.3.6.1.4.1.999.1:public@mydevice|Length2Int
See "Extended Host Name Syntax" below for complete target definition syntax information.
PER TARGET CONFIGURATION
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.
Target
With the Target keyword you tell mrtg what it should monitor. The Target keyword takes arguments in a wide range of
formats:
Basic
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.
Example:
Target[myrouter]: 2:publicATwellfleet-fddi.domain
If your community contains a "@" or a " " these characters must be escaped with a "\".
Target[bla]: 2:stu\ pi\@d@router
SNMPv2c
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, since we now use 64 bit instead of the normal 32 bit.
Example:
Target[myrouter]: 2:public@router1:::::2
SNMPv3
As an alternative to SNMPv2c, SNMPv3 provides access to the ifHC* counters, along with encryption. Not all devices
support SNMPv3, and you will also need the perl Net::SNMP library in order to use it. It is recommended that
cfgmaker be used to generate configurations involving SNMPv3, as it will check if the Net::SNMP library is loadable,
and will switch to SNMPv2c if v3 is unavailable.
SNMP v3 requires additional authentication parameters, passed using the SnmpOptions[] per-target keyword.
Example:
Target[myrouter]: 2:router1:::::3
SnmpOptions[myrouter]: username=>'user1'
noHC
Not all routers that support SNMPv2 or SNMPv3 provide the ifHC* counters on every interface. The noHC[] per-target
keyword signals that the low-speed counters ifInOctets and ifOutOctets should be queried instead. cfgmaker will
automatically insert this tag if SNMPv2 or SNMPv3 is specified but the ifHC* counters are unavailable.
Example:
Target[myrouter]: #Bri0:router1:::::3
SnmpOptions[myrouter]: username=>'user1'
noHC[myrouter]: yes
Reversing
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.
Example:
Target[ezci]: -1:publicATezci-ether.domain
Explicit OIDs
You can also explicitly define which 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.
Example:
Target[myrouter]: 1.3.6.1.2.1.2.2.1.14.1&1.3.6.1.2.1.2.2.1.20.1:public@myrouter
MIB Variables
MRTG knows a number of symbolic 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:
Example:
Target[myrouter]: ifInErrors.1&ifOutErrors.1:public@myrouter
SnmpWalk
It may be that you want to monitor an snmp object that is only reachable by 'walking'. You can get mrtg to walk by
prepending the OID with the string WaLK or if you want a particular entry from the table returned by the walk you can
use WaLKx where x is a number starting from 0 (!).
Example:
Target[myrouter]: WaLKstrangeOid.1&WaLKstrangeOid.2:public@myrouter
Target[myrouter]: WaLK3strangeOid.1&WaLK4strangeOid.2:public@myrouter
SnmpGetNext
A special case of an snmp object that is only reachable by 'walking' occurs when a single snmpgetnext will return the
correct value, but snmpwalk fails. This may occur with snmp V2 or V3, as the snmpgetbulk method is used in these
versions. You can get mrtg to use getnext instead of getbulk by prepending the OID with the string GeTNEXT.
Example:
Target[myrouter]: GeTNEXTstrangeOid&GeTNEXTstrangeOid:public@myrouter
Counted SNMP Walk
In other situations, an snmpwalk is needed to count rows, but the actual data is uninteresting. For example,
counting the number of mac-addresses in a CAM table, or the number of simultaneous dialup sessions. You can get MRTG
to count the number of instances by prepending the OID with the string CnTWaLK. The following will retrieve the
number of simultaneous VOIP calls on some routers:
Example:
Target[myrouter]: CnTWaLK1.3.6.1.4.1.9.10.55.1.1.1.1.3&CnTWaLK1.3.6.1.4.1.9.10.55.1.1.1.1.3: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 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 the current
ifindex. You can use IP addresses in every type of target definition by adding IP address of the numbered interface
after OID and separation char '/'.
Make sure that the given IP address is used on 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.
Example:
Target[myrouter]: /1.2.3.4:publicATwellfleet-fddi.domain
Target[ezci]: -/1.2.3.4:publicATezci-ether.domain
Target[myrouter]: ifInErrors/1.2.3.4&ifOutErrors/1.2.3.4:public@myrouter
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 except that the prefix to use is a \ instead of a /
You can tell cfgmaker to generate such references with the option --ifref=descr.
Example:
Target[myrouter]: \My-Interface2:publicATwellfleet-fddi.domain
Target[ezci]: -\My-Interface2:publicATezci-ether.domain
Target[myrouter]: ifInErrors\My-If2&ifOutErrors\My-If3:public@myrouter
If your description contains a "&", a ":", a "@" or a " " you can include them but you must escape with a backlash:
Target[myrouter]: \fun\:\ ney\&ddd:publicAThello.router
Interface by Name
This is the only sensible way to reference the interfaces of your switches.
You can tell cfgmaker to generate such references with the option --ifref=name.
Example:
Target[myrouter]: #2/11:publicATwellfleet-fddi.domain
Target[ezci]: -#2/11:publicATezci-ether.domain
Target[myrouter]: 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[myrouter]: #\:\ fun:publicAThello.router
Note that the # sign will be interpreted as a comment character if it is the first non white-space character on the
line.
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
the 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 of their Interfaces 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.
Example:
Target[myrouter]: !0a-0b-0c-0d:publicATwellfleet-fddi.domain
Target[ezci]: -!0-f-bb-05-71-22:publicATezci-ether.domain
Target[myrouter]: 1.3.6.1.2.1.2.2.1.14!0a-00-10-23-44-51& *BREAK*
1.3.6.1.2.1.2.2.1.14!0a-00-10-23-44-51:public@myrouter
Target[myrouter]: ifInErrors!0a-00-10-23-44-51& *BREAK*
ifOutErrors!0a-00-10-23-44-51:public@myrouter
Join the lines at *BREAK* ...
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 mention a persistent 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.
Example:
Target[myrouter]: %13:publicATwellfleet-fddi.domain
Target[ezci]: -%13:publicATezci-ether.domain
Target[myrouter]: ifInErrors%13&ifOutErrors%14:public@myrouter
Extended positioning of ifIndex
There are OIDs that contain the interface index at some inner position within the OID. To use the above mentioned
Interface by IP/Description/Name/Type methods in the target definition the keyword 'IndexPOS' can be used to indicate
the position of ifIndex. If 'IndexPOS' is not used the ifIndex will be appended at the end of the OID.
Example:
Target[myrouter]: OID.IndexPOS.1/1.2.3.4&OID.IndexPOS.1/1.2.3.4:public@myrouter
Replace OID by your numeric OID.
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. You can also append a pipe symbol ( | ) and the name of a numeric conversion
subroutine as described under the global keyword "ConversionCode" above. The full syntax is as follows:
community@router[:[port][:[timeout][:[retries][:[backoff][:[version]][|name]]]]]
where the meaning of each parameter is as follows:
port
the UDP port under which to contact the SNMP agent (default: 161)
The complete syntax of the port parameter is
remote_port[!local_address[!local_port]]
Some machines have additional security features that only allow SNMP queries to come from certain IP addresses.
If the host doing the query has multiple interface, it may be necessary to specify the interface the query should
come from.
The port parameter allows the specification of the port of the machine being queried. In addition, the IP address
(or hostname) and port of the machine doing the query may be specified.
Examples:
somehost
somehost:161
somehost:161!192.168.2.4!4000 use 192.168.2.4 and port 4000 as source
somehost:!192.168.2.4 use 192.168.2.4 as source
somehost:!!4000 use port 4000 as source
timeout
initial timeout for SNMP queries, in seconds (default: 2.0)
retries
number of times a timed-out request will be retried (default: 5)
backoff
factor by which the timeout is multiplied on every retry (default: 1.0).
version
for SNMP version. If you have a fast router you might want to put a '2' here. For authenticated or encrypted
SNMP, you can try to put a '3' here. This will make mrtg try to poll the 64 bit counters and thus prevent
excessive counter wrapping. Not all routers support this though. SNMP v3 requires additional setup, see
SnmpOptions[] for full details.
Example:
3:public@router1:::::2
name
the name of the subroutine that MRTG will call to convert the input and output values to integers. See the
complete example under the global keyword "ConversionCode" above.
Example:
1.3.6.1.4.1.999.1&1.3.6.1.4.1.999.2:public@mydevice:161::::2|Length2Int
This would retrieve values from the OID 1.3.6.1.4.1.999.1 for input and .2 for output on mydevice using UDP port
161 and SNMP version 2, and would execute the user-defined numeric conversion subroutine Length2Int to convert
those values to integers.
A value that equals the default value can be omitted. Trailing colons can be omitted, too. The pipe symbol followed
by the name parameter, if present, must come at the end. There must be no spaces around the colons or pipe symbol.
Example:
Target[ezci]: 1:publicATezci-ether.domain:9161::4
This would refer to the input/output octet counters for the interface with ifIndex 1 on ezci-ether.domain, 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.
Numeric IPv6 addresses
If IPv6 is enabled you may also specify a target using its IPv6 address. To avoid ambiguity with the port number,
numeric IPv6 addresses must be placed in square brackets.
Example:
Target[IPv6test]: 2:public@[2001:760:4::]:6161::4
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.
Example:
Target[myrouter]: `/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 ...
If your script does not have any data to return but does not want mrtg to complain about invalid data, it can return
'UNKNOWN' instead of a number. Note though that only rrdtool is realy equipped to handle unknown data well.
Multi Target Syntax
You can also combine several target definitions in a mathematical expression. Any syntactically correct expression
that the Perl interpreter can evaluate to will work. An expression could be used, for example, to aggregate both B
channels in an ISDN connection or to calculate the percentage hard disk utilization of a server from the absolute
used space and total capacity.
Examples:
Target[myrouter]: 2:public@wellfleetA + 1:public@wellfleetA
Target[myrouter]: .1.3.6.1.4.1.999.1&.1.3.6.1.4.1.999.2:public@mydevice /
.1.3.6.1.4.1.999.3&.1.3.6.1.4.1.999.4:public@mydevice * 100
Note that whitespace must surround each target definition in the expression. Target definitions themselves must not
contain whitespace, except in interface descriptions and interface names, where each whitespace character is escaped
by a backslash.
MRTG automatically rounds the result of the expression to an integer unless RRDTool logging is in use and the gauge
option is in effect for the target. Internally MRTG uses Perl's Math::BigFloat package to calculate the result of
the expression with 40 digits of precision. Even in extreme cases, where, for example, you take the difference of two
64-bit integers, the result of the expression should be accurate.
SNMP Request Optimization
MRTG is designed to economize on its SNMP requests. Where a target definition appears more than once in the
configuration file, MRTG requests the data from the device only once per round of data collection and uses the
collected data for each instance of a particular target. Recognition of two target definitions as being identical is
based on a simple string match rather than any kind of deeper semantic analysis.
Example:
Target[Targ1]: 1:public@CiscoA
Target[Targ2]: 2:public@CiscoA
Target[Targ3]: 1:public@CiscoA + 2:public@CiscoA
Target[Targ4]: 1:public@CISCOA
This results in a total of three SNMP requests. Data for 1:public@CiscoA and 2:public@CiscoA are requested only once
each, and used for Targ1, Targ2, and Targ3. Targ4 causes another SNMP request for 1:public@CISCOA, which is not
recognized as being identical to 1:public@CiscoA.
MaxBytes
The maximum value either of the two variables monitored are allowed to reach. For monitoring router traffic this is
normally the 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, 10 MB Ethernet = 1250000, 100 MB Ethernet = 12500000. 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.
Example:
MaxBytes[myrouter]: 1250000
Title
Title for the HTML page which gets generated for the graph.
Example:
Title[myrouter]: Traffic Analysis for Our Nice Company
OPTIONAL PER TARGET KEYWORDS
PageTop
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.
Example:
PageTop[myrouter]: <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
Second.
RouterUptime
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 you have to specify its community
and address again with the RouterUptime keyword.
If you want to use a special OID for queriing the router uptime, use prepend the oid.
Example:
Target[kacisco.comp.edu]: 1:publicAT194.250 + 2:publicAT194.250
RouterUptime[kacisco.comp.edu]: publicAT194.250
RouterUptime[kacisco.comp.edu]: hrSystemUptime.0:publicAT194.250
RouterName
If the default name of the router is incorrect/uninformative, you can use RouterName to specify a different OID on either
the same or a different host.
A practical example: sysName on BayTech DS72 units always display "ds72", no matter what you set the Unit ID to be.
Instead, the Unit ID is stored at 1.3.6.1.4.1.4779.1.1.3.0, so we can have MRTG display this instead of sysName.
Example:
RouterName[kacisco.comp.edu]: 1.3.6.1.4.1.4779.1.1.3.0
A different OID on a different host can also be specified:
RouterName[kacisco.comp.edu]: 1.3.6.1.4.1.4779.1.1.3.0:publicAT194.251
MaxBytes1
Same as MaxBytes, for variable 1.
MaxBytes2
Same as MaxBytes, for variable 2.
IPv4Only
Many IPv6 routers do not currently support SNMP over IPv6 and must be monitored using IPv4. The IPv4Only option forces
mrtg to use IPv4 when communicating with the target, even if IPv6 is enabled. This is useful if the target is a hostname
with both IPv4 and IPv6 addresses; without the IPv4Only keyword, monitoring such a router will not work if IPv6 is
enabled.
If set to no (the default), mrtg will use IPv6 unless the target has no IPv6 addresses, in which case it will use IPv4.
If set to yes, mrtg will only use IPv4.
Note that if this option is set to yes and the target does not have an IPv4 address, communication with the target will
fail.
This option has no effect if IPv6 is not enabled.
Example:
Target[v4onlyrouter_1]: 1:public@v4onlyrouter
IPv4Only[v4onlyrouter_1]: Yes
SnmpOptions (V3)
SNMPv3 requires a fairly rich set of options. This per-target keyword allows access to the User Security Model of
SNMPv3. Options are listed in the same syntax as a perl hash.
Security Modes
SNMPv3 has three security modes, defined on the device being polled. For example, on Cisco routers the security mode is
defined by the snmp-server group global configuration command.
NoAuthNoPriv
Neither Authentication nor Privacy is defined. Only the Username option is specified for this mode.
Example:
SnmpOptions[myrouter]: username=>'user1'
AuthNoPriv
Uses a Username and a password. The password can be hashed using the snmpkey application, or passed in plain text
along with the ContextEngineID
Example:
SnmpOptions[myrouter]: username=>'user1',authpassword=>'example',
contextengineid=>'80000001110000004000000'
Priv
Both Authentication and Privacy is defined. The default privacy protocol is des.
Example:
SnmpOptions[myrouter]: authkey=>'0x1e93ab5a396e2af234c8920e61cfe2028072c0e2',
authprotocol=>'sha',privprotocol=>'des',username=>'user1',
privkey=>'0x498d74940c5872ed387201d74b9b25e2'
snmp options
The following option keywords are recognized:
username
The user associated with the User Security Model
contextname
An SNMP agent can define multiple contexts. This keyword allows them to be polled.
contextengineid
A unique 24-byte string identifying the snmp-agent.
authpassword
The plaintext password for a user in either AuthNoPriv or Priv mode.
authkey
A md5 or sha hash of the plain-text password, along with the engineid. Use the snmpkey commandline program to
generate this hash, or use Net::SNMP::Security::USM in a script.
authprotocol {sha|md5}
The hashing algorithm defined on the SNMP client. Defaults to md5.
privpassword
A plaintext pre-shared key for encrypting snmp packets in Priv mode.
privkey
A hash of the plain-text pre-shared key, along with the engineid. Use the snmpkey commandline program to generate
this hash, or use Net::SNMP::Security::USM in a script.
privprotocol {des|3desede|aescfb128|aescfb192|aescfb256}
Specifies the encryption method defined on the snmp agent. The default is des.
PageFoot
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:
Example:
PageFoot[myrouter]: Contact <A HREF="mailto:peterATx.yz">Peter</A>
if you have questions regarding this page
AddHead
Use this tag like the PageTop header, but its contents will be added between </TITLE> and </HEAD>.
Example:
AddHead[myrouter]: <link rev="made" href="mailto:mrtgATblabla.edu">
BodyTag
BodyTag lets you supply your very own <body ...> tag for the generated webpages.
Example:
BodyTag[myrouter]: <BODY LEFTMARGIN="1" TOPMARGIN="1"
BACKGROUND="/stats/images/bg.neo2.gif">
AbsMax
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.
Example:
AbsMax[myrouter]: 2500000
Unscaled
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. There is also a special case to unset the variable completely:
n=none. This could be useful in the event you need to override a global configuration. In the example scaling for the
yearly and the monthly graph are suppressed.
Example:
Unscaled[myrouter]: ym
WithPeak
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.
Examples:
WithPeak[myrouter]: ym
Suppress
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.
Example:
Suppress[myrouter]: y
Extension
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 (useful for getting a router name
out of a database).
Example:
Extension[myrouter]: phtml
Directory
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 myrouter to be put into
directory /usr/tardis/pub/www/stats/mrtg/myrouter/ .)
The directory must already exist; mrtg will not create it.
Example:
WorkDir: /usr/tardis/pub/www/stats/mrtg
Directory[myrouter]: myrouter
NOTE: the Directory option must always be 'relative' or bad things will happen.
Clonedirectory
If the Directory option is specified, the Clonedirectory option will copy all the contents of Directory to the
Clonedirectory.
Example:
WorkDir: /usr/tardis/pub/www/stats/mrtg
Directory[myrouter]: myrouter
Clonedirectory[myrouter]: myclonedirectory
Optionally the target name can be changed in the cloning process.
Example:
WorkDir: /usr/tardis/pub/www/stats/mrtg
Directory[myrouter]: myrouter
Clonedirectory[myrouter]: myclonedirectory mynewtarget
NOTE1: The clone directory must already exist; mrtg will not create it.
NOTE2: The Clonedirectory option must also always be 'relative' or bad things will happen.
NOTE3: This requires the File::Copy module
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
Example:
XSize[myrouter]: 300
YSize[myrouter]: 300
XZoom and YZoom
If you want your graphs to have larger pixels, you can "Zoom" them.
Example:
XZoom[myrouter]: 2.0
YZoom[myrouter]: 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.
Example:
XScale[myrouter]: 1.5
YScale[myrouter]: 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 .
Example:
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[myrouter]: 7
YTicsFactor[myrouter]: 0.01
Factor
If you want to multiply all numbers shown below the graph with a constant factor, use this directive to define it ..
Example:
Factor[as400]: 4096
Step
Change the default step from 5 * 60 seconds to something else (I have not tested this much ...)
Example:
Step[myrouter]: 60
PNGTitle
When using rateup for graph generation, this will print the given title in the graph it generates.
Example:
PNGTitle[myrouter]: WAN Link UK-US
Options
The Options Keyword allows you to set some boolean switches:
growright
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.
bits
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.
perminute
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.
perhour
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.
noinfo
Suppress the information about uptime and device name in the generated webpage.
nopercent
Don't print usage percentages.
transparent
Make the background of the generated gifs transparent.
integer
Print summary lines below graph as integers without commas.
dorelpercent
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 if IN-traffic is greater than OUT-traffic then 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.
avgpeak
There are some ISPs who use the average Peak values to bill their customers. Using this option MRTG displays these
values for each graph. The value is built by averaging the max 5 minute traffic average for each 'step' shown in the
graph. For the Weekly graph this means that it builds the average of all 2 hour intervals 5 minute peak values.
(Confused? Thought so!)
gauge
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 variables as a counters 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.
absolute
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.
derive
If you are using rrdtool as logger/grapher you can use a third type of data source. Derive is like counter, except
that it is not required to go UP all the time. It is useful for situations where the change of some value should be
graphed.
unknaszero
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.
withzeroes
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.
noborder
If you are using rateup to log data, MRTG will create the graph images. Normally these images have a shaded border
around them. If you do not want the border to be drawn, enable this option. This option has no effect if you are not
using rateup.
noarrow
As with the option above, this effects rateup graph generation only. Normally rateup will generate graphs with a
small arrow showing the direction of the data. If you do not want this arrow to be drawn, enable this option. This
option has no effect if you are not using rateup.
noi When using rateup for graph generation, you can use this option to stop rateup drawing a graph for the 'I' or first
variable. This also removes entries for this variable in the HTML page MRTG generates, and will remove the peaks for
this variable if they are enabled. This allows you to hide this data, or can be very useful if you are only graphing
one line of data rather than two. This option is not destructive - any data received for the the variable continued
to be logged, it just isn't shown.
noo Same as above, except relating to the 'O' or second variable.
nobanner
When using rateup for graph generation, this option disables MRTG adding the MRTG banner to the HTML pages it
generates.
nolegend
When using rateup for graph generation, this option will stop MRTG from creating a legend at the bottom of the HTML
pages it generates.
printrouter
When using rateup for graph generation, this option will print the router name in the graph it generates. This
option is overridden by the value of PNGTitle if one is given
pngdate
When using rateup for graph generation, this option will print a timestamp in the graph it generates, including a
timezone if one is specified by the 'Timezone' parameter.
logscale
The logscale option causes rateup to display the data with the Y axis scaled logarithmically. Doing so allows the
normal traffic to occupy the majority of the vertical range, while still showing any spikes at their full height.
logscale displays all the available data and will always produce well-behaved graphs. People often consider a
logarithmically scaled graph counterintuitive, however, and thus hard to interpret.
expscale
The expscale option causes rateup to display the data with the Y axis scaled exponentially. Doing so emphasizes
small changes at the top of the scale; this can be useful when graphing values that fluctuate by a small amount near
the top of the scale, such as line voltage.
expscale is essentially the inverse of logscale.
secondmean
The secondmean option sets the maximum value on the graph to the mean of the data greater than the mean of all data.
This produces a graph that focuses more on the typical data, while clipping large peaks.
Using secondmean will give a more intutive linearly scaled graph, but can result in a uselessly high or low scale in
some rare situations (specifically, when the data includes a large portion of values far from the actual mean)
If a target includes both logscale and secondmean in the options, the secondmean takes precedence.
Example:
Options[myrouter]: growright, bits
kilo
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.
Example:
kilo[myrouter]: 1024
kMG
Change the default multiplier prefixes (,k,M,G,T,P). In the tag ShortLegend define only the basic units. Format: Comma
separated list of prefixed. Two consecutive commas or a comma at start or end of the line gives no prefix on this item.
If you do not want prefixes, just put two consecutive commas. If you want to skip a magnitude select '-' as value.
Example: velocity in nm/s (nanometers per second) displayed in nm/h.
ShortLegend[myrouter]: m/h
kMG[myrouter]: n,u,m,,k,M,G,T,P
options[myrouter]: perhour
Colours
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: Col1#RRGGBB,Col2#RRGGBB,Col3#RRGGBB,Col4#RRGGBB
Important: If you use the dorelpercent options tag a fifth colour name colour value pair is required:
Col1#RRGGBB,Col2#RRGGBB,Col3#RRGGBB,Col4#RRGGBB,Col5#RRGGBB
Colour1
First variable (normally Input) on default graph.
Colour2
Second variable (normally Output) on default graph.
Colour3
Max first variable (input).
Colour4
Max second variable (output).
RRGGBB
2 digit hex values for Red, Green and Blue.
Example:
Colours[myrouter]: GREEN#00eb0c,BLUE#1000ff,DARK GREEN#006600,VIOLET#ff00ff
Background
With the Background tag you can configure the background colour of the generated HTML page.
Example:
Background[myrouter]: #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:
YLegend
The Y-axis label of the graph. Note that a text which is too long to fit in the graph will be silently ignored.
ShortLegend
The units string (default 'b/s') used for Max, Average and Current
Legend[1234IO]
The strings for the colour legend.
Example:
YLegend[myrouter]: Bits per Second
ShortLegend[myrouter]: b/s
Legend1[myrouter]: Incoming Traffic in Bits per Second
Legend2[myrouter]: Outgoing Traffic in Bits per Second
Legend3[myrouter]: Maximal 5 Minute Incoming Traffic
Legend4[myrouter]: Maximal 5 Minute Outgoing Traffic
LegendI[myrouter]: In:
LegendO[myrouter]: Out:
Note, if LegendI or LegendO are set to an empty string with
LegendO[myrouter]:
The corresponding line below the graph will not be printed at all.
Timezone
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.
Example:
Timezone[myrouter]: Japan
The Timezone is the standard timezone of your system, ie Japan, Hongkong, GMT, GMT+1 etc etc.
Weekformat
By default, mrtg (actually rateup) uses the strftime(3) '%V' 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 correspond to the
widely used ISO 8601 week numbering standard. The week format character should be specified as a single letter; either
W, V, or U.
The UNIX version of rateup uses the libc implementation of strftime. On Windows, the native strftime implementation does
not know about %V. So there we use a different implementation of strftime that does support %V.
Example:
Weekformat[myrouter]: W
RRDRowCount
This affects the creation of new rrd files. By default rrds are created to hold about 1 day's worth of high resolution
data. (plus 1 week of 30 minute data, 2 months of 2 hour data and 2 years of 1 day data). With this Keyword you can
change the number of base interval entries configured for new rrds as they get created. Note that you must take the
interval time into account.
Example:
RRDRowCount[myrouter]: 1600
RRDRowCount30m
As per RRDRowCount, but for the RRA's -typically- used for 30 minute data. Even so, you must still take the base
interval into account. Leaving out this keyword will force the old default of 800 rows.
Example:
RRDRowCount30m[myrouter]: 800
RRDRowCount2h
As per RRDRowCount, but for the RRA's -typically- used for 2 hour data. Even so, you must still take the base interval
into account. Leaving out this keyword will force the old default of 800 rows.
Example:
RRDRowCount2h[myrouter]: 400
RRDRowCount1d
As per RRDRowCount, but for the RRA's -typically- used for 1 day data. Even so, you must still take the base interval
into account. Leaving out this keyword will force the old default of 800 rows.
Example:
RRDRowCount1d[myrouter]: 200
RRDHWRRAs
Normally the RRDs created by MRTG will just contain the information gathered directly from the respective target. With
this option you can tap into rrdtools advanced aberrant behaviour detection module based on Holt-Winters forecasting. The
RRDHWRRAs property specifies the Holt-Winters RRAs as described in the rrdcreate manual page.
Note, this setting will only affect newly created RRDs (targets).
Example:
RRDHWRRAs[myrouter]: RRA:HWPREDICT:1440:0.1:0.0035:288
TimeStrPos
This defines placement of the timestamp string on the image. Possible values are RU, LU, RL, LL (which stand,
respectively, for RightUpper, LeftUpper, RightLower and LeftLower corner) and NO (for no timestamp). By default, no
timestamp is placed on the image.
Example:
TimeStrPos[myrouter]: RU
TimeStrFmt
Using this keyword you may specify format of the timestamp to be placed on the image (if enabled by the TimeStrPos
keyword). Specified string will be used by the strftime() function - see strftime(3) documentation for conversion
specifiers available on your system. Default format: %Y-%m-%d %H:%M
Example:
TimeStrFmt[myrouter]: %H:%M:%S
THRESHOLD CHECKING
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 (e.g. send email or a page to an administrator).
Threshold checking is configured through the following parameters:
ThreshDir (GLOBAL)
By defining ThreshDir to point to a writable directory, MRTG will only alert you when a threshold boundery has been
crossed.
Example:
ThreshDir: /var/mrtg/thresh
ThreshHyst (GLOBAL)
If a threshold is broken, and you have a threshdir defined, then mrtg will send mail once the threshold becomes
'unborken' to avoid situations where broken and un-broken messages get sent in close succession, we only send an unbroken
message once the curent value is 0.1 (10%) away from the threshold. using the ThreshHyst config variable you can
customize this value.
Example for 5%:
ThreshHyst: 0.05
ThreshMailServer (GLOBAL)
Adderss of an SMTP server which is going to accept mail about Thresholds being broken and unbroken.
ThreshMailSender (GLOBAL)
What is the sender address of the threshold mail.
Example:
ThreshMailSender: mrtgATexample.com
ThreshMailAddress (PER TARGET)
Email address for Threshold related Mails. This will only work if a mailserver has been configured.
Example:
ThreshMailAddress[_]: adminATexample.com
ThreshMailAddress[router]:
This would bring threshold releaed mail to all but the target called 'router'.
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 and a mail will be sent to the ThreshMailAddress if specified. If the value
ends in '%' then the threshold is defined relative to MaxBytes.
ThreshMaxI (PER TARGET)
Works the same as TheshMinI but it acts when the value is higher than ThreshMaxI.
ThreshDesc (PER TARGET)
Its value will be assigned to the environment variable THRESH_DESC before any of the programs mentioned below are called.
The programs can use the value of this variable to produce more user-friendly output.
ThreshProgI (PER TARGET)
This defines a program to be run if ThreshMinI or ThreshMaxI is broken. MRTG passes 3 arguments: the $router variable,
the threshold value broken, and the current parameter value.
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. MRTG passes 3 arguments: the $router variable the unbroken
threshold value, and the current parameter value.
ThreshMinO, ThreshMaxO, ThreshProgO, and ThreshProgOKO
These work the same as their *I counterparts, except on the Output (second) parameter.
SetEnv
When calling threshold scripts from within your cfg file you might want to pass some data on to the script. This can be
done with the SetEnv configuration option which takes a series of environment variable assignments. Note that the quotes
are mandatory. This does not work for external scripts. It is not possible to set environment variables per target.
Example:
SetEnv[myrouter]: EMAIL="contact_emailATsomeplace.net"
HOST="www.some_server.net"
HW Failure Bassed Threshold Checking
When using rrd based logging with HW RRAs defined. You can use the confidence bounds violations stored in the FAILURES
RRA for threshold based alerts.
There the all target specific threshold variables have a Hold-Winters counterpart:
ThreshMailAddress -> HWThreshMailAddress
ThreshMinI -> HWThreshMinI
...
The global variables for threshold checking are shared except for the
ThreshHyst -> HWThreshHyst
And HWThreshDesc sets the HWTHRESH_DESC variable.
PER TARGET DEFAULT VALUES
Pre- and Postfix
To save yourself some typing you can define a target called '^'. The text of every Keyword you define for this target
will be PREPENDED to the corresponding Keyword of all the targets defined below this line. The same goes for a Target
called '$' 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.
Example:
PageTop[^]: <H1>NoWhere Unis Traffic Stats</H1><HR>
PageTop[$]: Contact Peter Norton if you have any questions<HR>
To remove the prepend/append value, specify an empty value, e.g.:
PageTop[^]:
PageTop[$]:
NoSpaceChar
With PREPEND and APPEND (see below) 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 global option NoSpaceChar to define a character which can be
mentioned at the end of a $ or ^ definition in order to supress the space.
Example:
NoSpaceChar: ~
Target[^]: 1.3.6.1.4.1.482.50.2.4.20.0&1.3.6.1.4.1.482.50.2.4.21.0:get@~
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.
Example:
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.:
YLegend[_]:
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.
Example:
MaxBytes[_]: 1250000
Target[myrouter.somplace.edu.2]: 2:publicATmyrouter.edu
MaxBytes[_]: 8000
Title[myrouter.somplace.edu.2]: Traffic Analysis for myrouter.somplace.edu IF 2
The default MaxBytes for the target myrouter.someplace.edu.2 in the above example will be 1250000, which was in effect
where the target name myrouter.someplace.edu.2 first appeared in the config file.
COMMAND LINE OPTIONS
--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 included with 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 you go to the mrtg contrib download area (on the website) you will find the mrtg-message-dll.zip
which does contain such a thing.
--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; http://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
--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
coca - confcache operations
fork - forking view
time - some timing info
log - logging of data via rateup or rrdtool
eval - print eval strings before evaluting them
prof - add hires timing info the rrd calls
Example:
--debug="cfg,snpo"
EXIT CODES
An exit code of 0 indicates that all targets were successful. Generally speaking, most codes greater than 0 indicate
that there was an unrecoverable problem. One exception to this is code 91, which indicates that at least one of the
targets was successful. A partial listing of the codes follows:
0: All targets sucessful
2: Config error (can't read, fatal error in config, etc)
17: Another MRTG process is processing config
91: At least one target sucessful
92: No targets were sucessful
EXAMPLES
Minimal mrtg.cfg
WorkDir: /usr/tardis/pub/www/stats/mrtg
Target[r1]: 2:publicATmyrouter.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:publicATrouter.edu
Title[backb]: our Campus Backbone
PageTop[backb]: our Campus Backbone</H1>
Target[backb]: 1:publicATrouter.edu
MaxBytes[backb]: 1250000
# the following line removes the default prepend value
# defined above
Title[^]:
Title[isdn2]: Traffic for the Backup ISDN Line
PageTop[isdn2]: our ISDN Line</H1>
Target[isdn2]: 3:publicATrouter.edu
AUTHOR
Tobias Oetiker <tobiAToetiker.ch> and many contributors
2.16.4 2010-05-17 MRTG-REFERENCE(1)
