[mrtg] Re: Newbie answer from newbie question

Elsie Simonton elsiels at srttel.com
Mon Nov 8 20:53:38 MET 1999

Maybe I am not finding the right stuff to read as I still do not understand this.  What I am trying to do is look at a modem rack with 8 modems on it.  When I do an snmpwalk, I end up with pages of info.  
So I went back to trying to use the numbers that we were given by the manufacture which are 
ublic at XXX.XXX.XXX
I can not get a snmpget to work on these numbers and the info is blank.  

I understand the tree that you showed me yet with those numbers snmpget did not work either.  
What reading am I missing to understand how this stuff works and where to get the numbers for our machine. 
>>> Robin Burger <robin.burger at bms.com> 11/03 8:53 AM >>>

NOTE To everyone:  If any of this is 'incorrect' let me know... I am also just trying to figure out MRTG, SNMP and a couple of other items...

 Subject:  [mrtg] Re: How do I find 'every' MIB on my machine?
    Date:  Tue, 02 Nov 1999 16:55:20 -0600
    From:  Elsie Simonton <elsiels at srttel.com>
      To:  robin.burger at bms.com, mrtg at list.ee.ethz.ch 

>> I am in training at my office (just out of college) and
>> am trying to figure out this MIB thing.
>> How do I query my device  a total control arc card
>> (for 8 modem cards) to find the mib.
>> I recently downloaded cmu then ran snmpget on
>> interfaces.ifNumber.0.  The result I got said 172.

((( 'Warning' this is for
# snmpget -V
UCD-snmp version: 4.0.1

# snmpwalk localhost public
(( will list all of the OID's that are on your local system - you can
   substitute the machine you are looking at's name in this location

# snmpwalk localhost public | grep ifNumber
interfaces.ifNumber.0 = 2
(( just so that I can find out what it is that you did... ))

# snmpget -q -f localhost public interfaces.ifNumber.0
.iso.org.dod.internet.mgmt.mib-2.interfaces.ifNumber.0 2
(( so this gives us the OID that is complete, but we do not know
    how to translate it...))

(( in your 'mrtg-2.8.6/run/' directory you will find a file
   called '''SNMP_util.pm''' that will help you translate
   the simple ones

((( .iso.org.dod.internet.mgmt.mib-2.interfaces.ifNumber.0
      1 . 3 . 6 .    1   . 2  .  1  .    2     .   1    .0

           'iso' => '1',
           'org' => '1.3',
           'dod' => '1.3.6',
      'internet' => '',
          'mgmt' => '',
         'mib-2' => '',
    'interfaces' => '',
      'ifNumber' => '',


(( if you check for a file called 'IF-MIB.txt' on your system
   you can search for 'ifNumber' and look for the line that
   looks like this...

   ifNumber  OBJECT-TYPE
   (( line 99 in IF-MIB.txt ))

   Just below it you will find out another line that looks like

       ::= { interfaces 1 }
   (( line 106))

   This means that 'ifNumber ~ interface 1' or in the translation
   from the above OID, since we know that the preceding part
   of the tree is 'interfaces', then we know we have the correct
   'ifNumber' and now we look for 'interfaces'

    interfaces   OBJECT IDENTIFIER ::= { mib-2 2 }
   (( line 43 ))

   So now we can look at it as walking the tree backwards...

                       'ifNumber' ~ interfaces.1
               'interfaces' ~ mib-2.2

   .iso.org.dod.internet.mgmt.mib-2.     2    .    1   .0

    And so far the only other place I have found the rest of
    the translation of the tree backwards is in 'SNMP_util.pm'.
    In other words, you read it from right to left.
    Makes for efficient lookup.

    NOTE:  You can modify 'SNMP_util.pm' to add in your own 'specific'
           OID's, but the better place is in the MRTG code as it actually
           has a place that calls 'SNMP_util.pm' and adds the ones included
           into MRTG into the rest that are in 'SNMP_util.pm'.


((( .iso.org.dod.internet.mgmt.mib-2.interfaces.ifNumber.0
      1 . 3 . 6 .    1   . 2  .  1  .    2     .   1    .0

So now we have a OID to use... right?

# snmpget localhost public
Error in packet
Reason: (noSuchName) There is no such variable name in this MIB.
This name doesn't exist: system.sysUpTime.
((( seems that it didn't like that OID... turn out that
    the is defaulted... so try instead

# snmpget localhost public 2.1.0
interfaces.ifNumber.0 = 2

((( Now, for MRTG you have to use the full OID ''
    but when you do, if your '.cfg' file in your configs directory
    is not done correctly - it 'Will not work'.

    1) make sure you have a WorkDir set up:

       WorkDir: /export/home/mrtg/data

    2) make sure your target has the OID twice with an '&' in between them.

 Target[localhost.fully.qualified.domain.com]: at localhost

    3) Run MRTG and Check in your data directory that the
       localhost.fully.qualified.domain.com.log file gets created.

    4) When information in the '.log' doesn't increment modify the
       '.cfg' file so that 'Options' uses 'gage absolute'.

  Options[localhost.fully.qualified.domain.com.com]: gauge absolute

    5) Re-Check '.log' file and you should see the numbers increase.

# egrep -v  '^#|^$' localhost.cfg
WorkDir: /absolute/path/name/to/your/./mrtg/data
Target[localhost.fully.qualified.domain.com]: at localhost
RouterUptime[localhost.fully.qualified.domain.com]: public at localhost
MaxBytes[localhost.fully.qualified.domain.com]: 100
AbsMax[localhost.fully.qualified.domain.com]: 400
Title[localhost.fully.qualified.domain.com]:    TBD
WithPeak[localhost.fully.qualified.domain.com]: ymw
Unscaled[localhost.fully.qualified.domain.com]: ymw
ShortLegend[localhost.fully.qualified.domain.com]: %
XSize[localhost.fully.qualified.domain.com]: 380
YSize[localhost.fully.qualified.domain.com]: 100
YLegend[localhost.fully.qualified.domain.com]: ifNumber
Legend1[localhost.fully.qualified.domain.com]: What makes sense here TBD
Legend2[localhost.fully.qualified.domain.com]: TBD To Be Determined
Legend3[localhost.fully.qualified.domain.com]: TBD
Legend4[localhost.fully.qualified.domain.com]: TBD
LegendI[localhost.fully.qualified.domain.com]: TBD
Options[localhost.fully.qualified.domain.com]: gauge absolute
PageTop[localhost.fully.qualified.domain.com]: <H1>TBD</H1>
   <TR><TD>System:</TD><TD>localhost in Look behind you</TD></TR>
   <TR><TD>Maintainer:</TD><TD>Your Name goes here <Mail.address at nice.to.givelIER ::= { mib-2 2 }
   (( line> </TD></TR>
   <TR><TD>IP:</TD><TD>localhost.fully.qualified.domain.com (ip.numbers.go.here)</TD></TR>
   <TR><TD>Filled in automatically</TD>
       <TD>filled in automatically</TD></TR>

>> When I put this info in MRTG  .
>> it doesn't like it.  What am I misreading or what else
>> do I need to read in order to understand the mibs better?
>> Thank you anyone for helping me as I am currently lost.

How does that look... make any better sense?


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