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PROGRAM:

NAME


mrtg-reference - MRTG 2.17.4 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:

· Keywords must start at the beginning of a line.

· Lines which follow a keyword line which 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

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. The current working directory will be searched first.

If the included filename contains an asterisk, then this is taken as a wildcard for
zero or more characters, and all matching files are included. Thus, you can use this
statement to include all files in a specified subdirectory.

Example:

Include: servers/*.cfg

In this case, you should be very careful that your wildcard pattern does not find a
match relative to the current working directory if you mean it to be relative to the
main config file directory, since the working directory is checked for a match first
(as with a normal Include directive). Therefore, use of something like '*/*' is
discouraged.

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:

· The generated HTML page contains 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.

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/

RRDCached
If you are running RRDTool 1.4 or later with rrdcached, then you can configure MRTG to
take advantage of this for updates, either by using the RRDCACHED_ADDRESS environment
variable, or by setting the RRDCached keyword in the configuration file. Note that, if
both are set, the configuration file keyword will take precedence.

Only UNIX domain sockets are fully supported prior to RRDTool v1.5, and you should note
that using RRDCached mode will disable all Threshold checking normally done by MRTG.
Appropriate warning messages will be printed if necessary.

Examples:

RRDCached: unix:/var/tmp/rrdcached.sock

RRDCached: localhost:42217

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 on
startup, and if the configuration file is modified.

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.

If the modification date on the configuration file changes during operation, then MRTG
will re-read the configuration on the next polling cycle. Note that sub-files which are
included from the main configuration do not have their modification times monitored, only
the top-level file is so checked.

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:[email protected]

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:[email protected]

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:[email protected]
Target[ezci]: -/1.2.3.4:[email protected]
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:[email protected]
Target[ezci]: -\My-Interface2:[email protected]
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:[email protected]

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:[email protected]
Target[ezci]: -#2/11:[email protected]
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:[email protected]

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:[email protected]
Target[ezci]: -!0-f-bb-05-71-22:[email protected]
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:[email protected]
Target[ezci]: -%13:[email protected]
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:[email protected]: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 normally 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 querying the router uptime, use prepend the oid.

Example:

Target[kacisco.comp.edu]: 1:[email protected] + 2:[email protected]
RouterUptime[kacisco.comp.edu]: [email protected]

RouterUptime[kacisco.comp.edu]: hrSystemUptime.0:[email protected]

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:[email protected]

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:[email protected]">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:[email protected]">

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. This is aequivalent to setting TimeStrPost[x]: RU

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]: &nbsp;In:
LegendO[myrouter]: &nbsp;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 boundary 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 unbroken 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: [email protected]

ThreshMailAddress (PER TARGET)
Email address for Threshold related Mails. This will only work if a mailserver has been
configured.

Example:

ThreshMailAddress[_]: [email protected]
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="[email protected]"
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:[email protected]
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:[email protected]
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:[email protected]

Title[backb]: our Campus Backbone
PageTop[backb]: our Campus Backbone</H1>
Target[backb]: 1:[email protected]
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:[email protected]

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