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.\" ========================================================================

.\"

.IX Title "MRTG-REFERENCE 1"

.TH MRTG-REFERENCE 1 "2018-07-13" "2.17.7" "mrtg"

.\" For nroff, turn off justification.  Always turn off hyphenation; it makes

.\" way too many mistakes in technical documents.

.if n .ad l

.nh

.SH "NAME"

mrtg\-reference \- MRTG 2.17.7 configuration reference

.SH "OVERVIEW"

.IX Header "OVERVIEW"

The runtime behaviour of \s-1MRTG\s0 is governed by a configuration file.

Run-of-the-mill configuration files can be generated with \fBcfgmaker\fR.

(Check cfgmaker). But for more elaborate configurations some hand-tuning

is required.

.PP

This document describes all the configuration options understood by

the mrtg software.

.SH "SYNTAX"

.IX Header "SYNTAX"

\&\s-1MRTG\s0 configuration file syntax follows some simple rules:

.IP "\(bu" 4

Keywords must start at the beginning of a line.

.IP "\(bu" 4

Lines which follow a keyword line which start

with a blank are appended to the keyword line

.IP "\(bu" 4

Empty Lines are ignored

.IP "\(bu" 4

Lines starting with a # sign are comments.

.IP "\(bu" 4

You can add other files into the configuration file using

.Sp

\&\fBInclude:\fR \fIfile\fR

.Sp

Example:

.Sp

.Vb 1

\& Include: base\-options.inc

.Ve

.Sp

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.

.Sp

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.

.Sp

Example:

.Sp

.Vb 1

\& Include: servers/*.cfg

.Ve

.Sp

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.

.SH "GLOBAL KEYWORDS"

.IX Header "GLOBAL KEYWORDS"

.SS "WorkDir"

.IX Subsection "WorkDir"

WorkDir specifies where the logfiles and the webpages should

be created.

.PP

Example:

.PP

.Vb 1

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

.Ve

.SH "OPTIONAL GLOBAL KEYWORDS"

.IX Header "OPTIONAL GLOBAL KEYWORDS"

.SS "HtmlDir"

.IX Subsection "HtmlDir"

HtmlDir specifies the directory where the html (or shtml,

but we'll get on to those later) lives.

.PP

\&\s-1NOTE:\s0 Workdir overrides the settings for htmldir, imagedir

and logdir.

.PP

Example:

.PP

.Vb 1

\& Htmldir: /www/mrtg/

.Ve

.SS "ImageDir"

.IX Subsection "ImageDir"

ImageDir specifies the directory where the images live. They

should be under the html directory.

.PP

Example:

.PP

.Vb 1

\& Imagedir: /www/mrtg/images

.Ve

.SS "LogDir"

.IX Subsection "LogDir"

LogDir specifies the directory where the logs are stored.

This need not be under htmldir directive.

.PP

Example:

.PP

.Vb 1

\& Logdir: /www/mrtg/logs

.Ve

.SS "Forks (\s-1UNIX\s0 only)"

.IX Subsection "Forks (UNIX only)"

With system that supports fork (\s-1UNIX\s0 for example), mrtg can fork itself into multiple

instances while it is acquiring data via snmp.

.PP

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.

.PP

As far as I know \s-1NT\s0 can not fork so this option is not available on \s-1NT.\s0

.PP

Example:

.PP

.Vb 1

\& Forks: 4

.Ve

.SS "EnableIPv6"

.IX Subsection "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 \s-1SNMP\s0 over IPv6 and targets may be specified by their

numeric IPv6 addresses as well as by hostname or IPv4 address.

.PP

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.

.PP

Note that many routers do not currently support \s-1SNMP\s0 over IPv6. Use the

\&\fIIPv4Only\fR per target option for these routers.

.PP

IPv6 is disabled by default.

.PP

Example:

.PP

.Vb 1

\& EnableIPv6: Yes

.Ve

.SS "EnableSnmpV3"

.IX Subsection "EnableSnmpV3"

When set to yes, uses the Net::SNMP module instead of the \s-1SNMP_SESSION\s0 module for

generating snmp queries.  This allows the use of SNMPv3 if other snmpv3 parameters

are set.

.PP

SNMPv3 is disabled by default.

.PP

Example:

.PP

.Vb 1

\& EnableSnmpV3: yes

.Ve

.SS "Refresh"

.IX Subsection "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).

.PP

Example:

.PP

.Vb 1

\& Refresh: 600

.Ve

.SS "Interval"

.IX Subsection "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:

.IP "\(bu" 4

The generated \s-1HTML\s0 page contains the right

information about the calling interval ...

.IP "\(bu" 4

A \s-1META\s0 header in the generated \s-1HTML\s0 page will instruct

caches about the time-to-live of this page .....

.PP

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.

.PP

Example:

.PP

.Vb 1

\& Interval: 10

.Ve

.PP

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

.PP

.Vb 1

\& Interval: MM[:SS]

.Ve

.PP

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.

.SS "MaxAge"

.IX Subsection "MaxAge"

\&\s-1MRTG\s0 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.

.PP

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.

.PP

Example:

.PP

.Vb 1

\& MaxAge: 7200

.Ve

.PP

The example above will make mrtg refuse to update log files older than 2

hours (7200 seconds).

.SS "WriteExpires"

.IX Subsection "WriteExpires"

With this switch mrtg will generate .meta files for \s-1CERN\s0

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 \*(L"MetaDir .\*(R" and \*(L"MetaFiles on\*(R"

in your apache.conf or .htaccess file for this to work

.PP

\&\s-1NOTE:\s0 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

.PP

Example:

.PP

.Vb 1

\& WriteExpires: Yes

.Ve

.SS "NoMib2"

.IX Subsection "NoMib2"

Normally we ask the \s-1SNMP\s0 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.

.PP

An example of agents which do not implement base mib2 attributes are

Computer Associates \- Unicenter \s-1TNG\s0 Agents.  \s-1CA\s0 relies on using the base

\&\s-1OS SNMP\s0 agent in addition to its own agents to supplement the management

of a system.

.PP

Example:

.PP

.Vb 1

\& NoMib2: Yes

.Ve

.SS "SingleRequest"

.IX Subsection "SingleRequest"

Some \s-1SNMP\s0 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.

.PP

Examples

.PP

.Vb 1

\& SingleRequest: Yes

.Ve

.SS "SnmpOptions"

.IX Subsection "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:

.PP

.Vb 7

\& 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

.Ve

.PP

The values behind the options indicate the current default value.

Note that these settings \s-1OVERRIDE\s0 the per target timeout settings.

.PP

A per-target SnmpOptions[] keyword will override the global settings.  

That keyword is primarily for SNMPv3.

.PP

The 16bit request ids are the only way to query the broken \s-1SNMP\s0

implementation of \s-1SMC\s0 Barricade routers.

.PP

Example:

.PP

.Vb 1

\& SnmpOptions: retries => 2, only_ip_address_matching => 0

.Ve

.PP

Note that \s-1AS/400\s0 snmp seems to be broken in a way which prevents mrtg from

working with it unless

.PP

.Vb 1

\& SnmpOptions: lenient_source_port_matching => 1

.Ve

.PP

is set.

.SS "IconDir"

.IX Subsection "IconDir"

If you want to keep the mrtg icons in someplace other than the

working (or imagedir) directory, use the \fIIconDir\fR variable for

defining the url of the icons directory.

.PP

Example:

.PP

.Vb 1

\& IconDir: /mrtgicons/

.Ve

.SS "LoadMIBs"

.IX Subsection "LoadMIBs"

Load the \s-1MIB\s0 file(s) specified and make its OIDs available as

symbolic names. For better efficiancy, a cache of MIBs is maintained

in the WorkDir.

.PP

Example:

.PP

.Vb 1

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

.Ve

.SS "Language"

.IX Subsection "Language"

Switch output format to the selected Language (Check the \fItranslate\fR directory

to see which languages are supported at the moment. In this directory you

can also find instructions on how to create new translations).

.PP

Currently the following laguages are supported:

.PP

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

.PP

Example:

.PP

.Vb 1

\& Language: danish

.Ve

.SS "LogFormat"

.IX Subsection "LogFormat"

Setting LogFormat to 'rrdtool' in your mrtg.cfg file enables rrdtool mode.

In rrdtool mode, mrtg relies on \fBrrdtool\fR to do its logging. See mrtg-rrd.

.PP

Example:

.PP

.Vb 1

\& LogFormat: rrdtool

.Ve

.SS "LibAdd"

.IX Subsection "LibAdd"

If you are using rrdtool mode and your \fBrrdtool\fR 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.

.PP

Example:

.PP

.Vb 1

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

.Ve

.SS "PathAdd"

.IX Subsection "PathAdd"

If the \fBrrdtool\fR executable can not be found in the normal \f(CW\*(C`PATH\*(C'\fR, you can

use this keyword to add a suitable directory to your path.

.PP

Example:

.PP

.Vb 1

\& PathAdd: /usr/local/rrdtool/bin/

.Ve

.SS "RRDCached"

.IX Subsection "RRDCached"

If you are running RRDTool 1.4 or later with \fBrrdcached\fR, then you can 

configure \s-1MRTG\s0 to take advantage of this for updates, either by using the 

\&\s-1RRDCACHED_ADDRESS\s0 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.

.PP

Only \s-1UNIX\s0 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 \s-1MRTG. \s0 Appropriate warning messages will be printed if

necessary.

.PP

Examples:

.PP

.Vb 1

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

\& 

\& RRDCached: localhost:42217

.Ve

.SS "RunAsDaemon"

.IX Subsection "RunAsDaemon"

The RunAsDaemon keyword enables daemon mode operation. The purpose of daemon

mode is that \s-1MRTG\s0 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.

.PP

Using daemon mode \s-1MRTG\s0 itself is responible for timing the measurement

intervals. Therfore its important to set the Interval keyword to an

apropiate value.

.PP

Note that when using daemon mode \s-1MRTG\s0 should no longer be started from cron

as each new process runs forever. Instead \s-1MRTG\s0 should be

started from the command prompt or by a system startup script.

.PP

If you want mrtg to run under a particular user and group (it is not

recomended to run \s-1MRTG\s0 as root) then you can use the \fB\-\-user=\fR\fIuser_name\fR

and \fB\-\-group=\fR\fIgroup_name\fR options on the mrtg commandline.

.PP

.Vb 1

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

.Ve

.PP

Also note that in daemon mode restarting the process is required in order to

activate changes in the config file.

.PP

Under \s-1UNIX,\s0 the Daemon switch causes mrtg to fork into background after

checking its config file. On Windows \s-1NT\s0 the \s-1MRTG\s0 process will detach from

the console, but because the \s-1NT/2000\s0 shell waits for its children you have to

use this special start sequence when you launch the program:

.PP

.Vb 1

\& start /b perl mrtg mrtg.cfg

.Ve

.PP

You may have to add path information equal to what you add when you run mrtg

from the commandline.

.PP

Example

.PP

.Vb 2

\& RunAsDaemon: Yes

\& Interval:    5

.Ve

.PP

This makes \s-1MRTG\s0 run as a daemon beginning data collection every 5 minutes

.PP

If you are daemontools and still want to run mrtg as a daemon you can

additionally specify

.PP

.Vb 1

\& NoDetach:     Yes

.Ve

.PP

this will make mrtg run but without detaching it from the terminal.

.PP

If the modification date on the configuration file changes during operation,

then \s-1MRTG\s0 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.

.SS "ConversionCode"

.IX Subsection "ConversionCode"

Some devices may produce non-numeric values that would nevertheless

be useful to graph with \s-1MRTG\s0 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), \s-1MRTG\s0 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 \s-1MRTG\s0 log file using

Perl's warn function. \s-1MRTG\s0 imports the subroutines into a separate name space

(package MRTGConversion), so the user need not worry about pollution of \s-1MRTG\s0's

global name space. \s-1MRTG\s0 automatically prepends this package declaration to

the user-supplied code.

.PP

Example: Suppose a particular \s-1OID\s0 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 \s-1MRTG,\s0 create a file arbitrarily named

\&\*(L"MyConversions.pl\*(R" containing the following code:

.PP

.Vb 5

\& # Return the length of the string argument

\& sub Length2Int {

\&   my $value = shift;

\&   return length( $value );

\& }

.Ve

.PP

Then include the following global keyword in the \s-1MRTG\s0 configuration file

(assuming that the conversion code file is saved in the mrtg/bin directory

along with mrtg itself):

.PP

.Vb 1

\& ConversionCode: MyConversions.pl

.Ve

.PP

This will cause \s-1MRTG\s0 to include the definition of the subroutine Length2Int

in its execution environment. Length2Int can then be invoked on any target

by appending \*(L"|Length2Int\*(R" to the target definition as follows:

.PP

.Vb 1

\& Target[myrouter]: 1.3.6.1.4.1.999.1&1.3.6.1.4.1.999.1:public@mydevice|Length2Int

.Ve

.PP

See \*(L"Extended Host Name Syntax\*(R" below for complete target definition syntax

information.

.SS "SendToGraphite"

.IX Subsection "SendToGraphite"

If you want to send a copy of the collected data into a Graphite database in addition

to storing it in the RRDfile, you can provide your Graphite database name/ip and port

number here.

.PP

This requires the Net::Graphite perl module which is available from \s-1CPAN.\s0

.PP

Examples:

.PP

.Vb 2

\& # If your Graphite receiver is running on the same host as the MRTG daemon and using the default port 

\& SendToGraphite: 127.0.0.1,2003

\&

\& # If your Graphite receiver is running on 192.168.100.50 port 5000

\& SendToGraphite: 192.168.100.50,5000

\&

\& # If your Graphite receiver is running on graphite.mydomain.com port 2003

\& SendToGraphite: graphite.mydomain.com,2003

.Ve

.PP

Graphite's namespace has a number of restrictions on what characters are 

allowed. The SendToGraphite functionality makes an attempt to convert the \s-1MRTG \s0

target name and, if specified, the Legendi and Legendo values to Graphite namespace

friendly values. Specifically, the following conversion rules apply:

.IP "\(bu" 4

Underscores in the target_name are converted to periods which are Graphite namespace delimiters.

.IP "\(bu" 4

Comma characters are not allowed so they are removed.

.IP "\(bu" 4

The string \*(L"m2g\*(R" for \s-1MRTG\s0 to Graphite is prepended onto the Graphite namespace variable.

.PP

Example \s-1MRTG\s0 target to Graphite namespace conversion:

.PP

.Vb 2

\& # Our MRTG target name from mrtg.cfg is as follows

\& Target[switch_GigabitEthernet0_5]: \eGigabitEthernet0/5:public1@switch:::::2

.Ve

.PP

After the conversion you will end up with these Graphite namespace values

.PP

.Vb 2

\& m2g.switch.gigabitethernet0.5.in

\& m2g.switch.gigabitethernet0.5.out

.Ve

.PP

Next is a more complicated example because Legendi and Legendo are in use to denote min and max

voltage values that pertain to some \s-1APC UPS SNMP\s0 OIDs

.PP

.Vb 4

\& # Target, Legendi, and Legendo are specified in mrtg.cfg as follows

\& Target[apc_minmaxline]: 1.3.6.1.4.1.318.1.1.1.3.2.3.0&1.3.6.1.4.1.318.1.1.1.3.2.2.0:public@apc:

\& LegendI[apc_minmaxline]: upsAdvInputMinLineVoltage

\& LegendO[apc_minmaxline]: upsAdvInputMaxLineVoltage

.Ve

.PP

After the conversion you will end up with these Graphite namespace values

.PP

.Vb 2

\& m2g.apc.minmaxline.upsAdvInputMinLineVoltage

\& m2g.apc.minmaxline.upsAdvInputMaxLineVoltage

.Ve

.PP

If you don't see the data showing up in Graphite, chances are there are invalid characters in

the namespace. To debug this, use the DEBUG=qw(log) directive at the top of the \s-1MRTG\s0 script 

to find out what is happening with the \s-1MRTG\s0 to Graphite namespace conversion.

.PP

DEBUG=qw(log) will generate some output similar to what appears below

.PP

.Vb 2

\& 2016\-10\-13 06:08:39 \-\- \-\-log: RRDs::update(/var/www/mrtg/switch/switch_gigabitethernet0_5.rrd, \*(Aq1476356919:2738746035:2927936327\*(Aq)

\& 2016\-10\-13 06:08:39 \-\- \-\-log: graphite\->send(m2g.switch.gigabitethernet0.5.in,2738746035,1476356919)

\&

\& 2016\-10\-13 06:08:39 \-\- \-\-log: graphite\->send(m2g.switch.gigabitethernet0.5.out,2927936327,1476356919)

\&

\& 2016\-10\-13 06:09:25 \-\- \-\-log: RRDs::update(/var/www/mrtg/apc/apc_minmaxline.rrd, \*(Aq1476356965:122:123\*(Aq)

\& 2016\-10\-13 06:09:25 \-\- \-\-log: graphite\->send(m2g.apc.minmaxline.upsAdvInputMinLineVoltage,122,1476356965)

\&

\& 2016\-10\-13 06:09:25 \-\- \-\-log: graphite\->send(m2g.apc.minmaxline.upsAdvInputMaxLineVoltage,123,1476356965)

.Ve

.PP

If the \s-1MRTG\s0 log output looks reasonable, then take a look at Graphite's carbon-cache logs.

.SH "PER TARGET CONFIGURATION"

.IX Header "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.

.SS "Target"

.IX Subsection "Target"

With the \fITarget\fR keyword you tell mrtg what it should

monitor. The \fITarget\fR keyword takes arguments in a wide

range of formats:

.IP "Basic" 4

.IX Item "Basic"

The most basic format is \*(L"port:community@router\*(R"

This will generate a traffic graph for the interface 'port'

of the host 'router' (dns name or \s-1IP\s0 address)

and it will use the community 'community' (snmp password)

for the snmp query.

.Sp

Example:

.Sp

.Vb 1

\& Target[myrouter]: 2:public@wellfleet\-fddi.domain

.Ve

.Sp

If your community contains a \*(L"@\*(R" or a \*(L" \*(R" these characters

must be escaped with a \*(L"\e\*(R".

.Sp

.Vb 1

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

.Ve

.IP "SNMPv2c" 4

.IX Item "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.

.Sp

Example:

.Sp

.Vb 1

\& Target[myrouter]: 2:public@router1:::::2

.Ve

.IP "SNMPv3" 4

.IX Item "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.

.Sp

\&\s-1SNMP\s0 v3 requires additional authentication parameters, passed using the 

SnmpOptions[] per-target keyword.

.Sp

Example:

  Target[myrouter]: 2:router1:::::3

  SnmpOptions[myrouter]: username=>'user1'

.IP "noHC" 4

.IX Item "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.

.Sp

Example:

  Target[myrouter]: #Bri0:router1:::::3

  SnmpOptions[myrouter]: username=>'user1'

  noHC[myrouter]: yes

.IP "Reversing" 4

.IX Item "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 \*(L"Target\*(R"

description. It flips the incoming and outgoing traffic rates.

.Sp

Example:

.Sp

.Vb 1

\& Target[ezci]: \-1:public@ezci\-ether.domain

.Ve

.IP "Explicit OIDs" 4

.IX Item "Explicit OIDs"

You can also explicitly define which \s-1OID\s0 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.  \s-1MRTG\s0 needs to graph two variables,

so you need to specify two \s-1OID\s0's such as temperature and humidity

or error input and error output.

.Sp

Example:

.Sp

.Vb 1

\& 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

.Ve

.IP "\s-1MIB\s0 Variables" 4

.IX Item "MIB Variables"

\&\s-1MRTG\s0 knows a number of symbolic \s-1SNMP\s0 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:

.Sp

Example:

.Sp

.Vb 1

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

.Ve

.IP "SnmpWalk" 4

.IX Item "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 \s-1OID\s0 with the string

\&\fBWaLK\fR or if you want a particular entry from the table returned by the walk

you can use \fBWaLK\fR\fIx\fR where \fIx\fR is a number starting from 0 (!).

.Sp

Example:

.Sp

.Vb 1

\&  Target[myrouter]: WaLKstrangeOid.1&WaLKstrangeOid.2:public@myrouter

\&

\&  Target[myrouter]: WaLK3strangeOid.1&WaLK4strangeOid.2:public@myrouter