View source for TUT:Using and loading MIBS

== Using local MIBs ==

The net-snmp tools can translate numeric object identifies
(OIDs) into textual object identifiers using the MIB description
files.  The net-snmp toolkit provides a few of the standard
MIBs, but certainly doesn't contain all the MIBs known to man.

First off, you should know about the paths that the tools load
MIBs from.  By default, it loads things from the following list
of directories:

# $HOME/.snmp/mibs
# /usr/local/share/snmp/mibs

So, lets say you have a MIB called
[ftp://ftp.cisco.com/pub/mibs/v2/CISCO-RHINO-MIB.my  CISCO-RHINO-MIB]
that you want parsed (it really exists, and I particularly liked
the name so I'm using it in the tutorial).  Place the file in
one of the above two directories.  If you pulled it from another
file (like an RFC), make sure it doesn't contain anything
non-MIB related (like the text leading up to it, and the page
separators).  The very first line in the file should begin with
something like "CISCO-RHINO-MIB DEFINITIONS ::= BEGIN", and the
very last line of the file should be "END"

Now, pick a node in the file that you want to translate that
currently isn't being translated.  From the CISCO-RHINO-MIB, I'll
pick the <i>ciscoLS1010ChassisFanLed</i> node.

First, lets verify that our handy snmptranslate command
(discussed [[TUT:snmptranslate|snmptranslate]]) doesn't
yet know about this node:

  % '''snmptranslate -IR -On ciscoLS1010ChassisFanLed'''
  Unknown object identifier: ciscoLS1010ChassisFanLed

Nope, it doesn't.  So, first we need to download the [ftp://ftp.cisco.com/pub/mibs/v2/CISCO-RHINO-MIB.my  CISCO-RHINO-MIB]
file and place it in a directory that our snmp tools can find it
in.  So, I'm going to place the file in $HOME/.snmp/mibs.

Now, lets use the ''-m'' flag to snmptranslate to tell it to
load that mib.  We'll use ''"-m +CISCO-RHINO-MIB"'' to indicate that
we want the tool to load not only the default set of mibs, but the
CISCO-RHINO-MIB as well (the leading '+' plus means "also").

  '''% snmptranslate -m +CISCO-RHINO-MIB -IR -On ciscoLS1010ChassisFanLed'''
  Cannot find module (CISCO-SMI): At line 31 in $HOME/.snmp/mibs/CISCO-RHINO-MIB.my
  Unlinked OID in CISCO-RHINO-MIB: ciscoLS1010ChassisMIB ::= { workgroup 11 }
  Cannot adopt OID in CISCO-RHINO-MIB: ciscoAtmSwitchInvalidCellHeader ::= { ciscoAtmSwitchInvalidCellHeaderEntry 2 }
  ''... rest of output truncated ...</i>''

Wait a minute...  What the heck is all that stuff?  Errors!  Well,
the first line is the most important and it's telling us that we're
missing the CISCO-SMI MIB as well.  So, if we go
[ftp://ftp.cisco.com/pub/mibs/v2/CISCO-SMI.my  download that MIB file]
and place it in our $HOME/.snmp/mibs directory as
well the command should suddenly work:

  % '''snmptranslate -m +CISCO-RHINO-MIB -IR -On ciscoLS1010ChassisFanLed'''
  .1.3.6.1.4.1.9.5.11.1.1.12

'''Success!'''

One last comment: You can also force loading of a given MIB and
its node in one fell swoop (and this method is the one most highly
recommended by Niels Baggesen, one of our primary core
developers):

  % '''snmptranslate -On CISCO-RHINO-MIB::ciscoLS1010ChassisFanLed'''
  .1.3.6.1.4.1.9.5.11.1.1.12

So, there you have it.  A complete example for how to get your
own ''insert-spiffy-mib-here'' loaded into the net-snmp tools.


=== Yes, but how do I make it happen all the time? ===

Good question.  And of course, we have multiple options for you.
We support a number of ways of doing this.


* First, you can put the following lines in a snmp.conf file.  This file can be placed in a system-wide location (EG, ''/usr/local/share/snmp.conf'') or in a personal file (EG, $HOME/.snmp/snmp.conf):

  mibs +CISCO-RHINO-MIB
  mibs +SOME-OTHER-SPIFFY-MIB

* You can also use the MIBS environment variable to specify things (example assumes a /bin/sh style shell):

  MIBS=+CISCO-RHINO-MIB:SOME-OTHER-SPIFFY-MIB
  export MIBS

* For the brave you can load all MIB files in your system-wide location - This can save you time, but may give you errors as shown below.

To snmp.conf:  
  
  mibs +ALL

And to run it: 
  
  '''% snmpwalk -v2c public 192.168.1.100'''
  Warning: Module MAU-MIB was in /usr/share/snmp/mibs//DOT3-MAU-MIB.txt now is /usr/share/snmp/mibs//RFC2668-MIB.txt
  Warning: Module DISMAN-EVENT-MIB was in /usr/share/snmp/mibs//EVENT-MIB.txt now is /usr/share/snmp/mibs//DISMAN-EVENT-MIB.txt
  Warning: Module P-BRIDGE-MIB was in /usr/share/snmp/mibs//P-BRIDGE-MIB.txt now is /usr/share/snmp/mibs//P-BRIDGE.txt

Although, with enabling so many SNMP MIBs at once comes a consequence as seen above.  Pipe the stdout to null for cleaner output.

  '''% snmpwalk -v2c public 192.168.1.100 2>/dev/null'''
  SNMPv2-MIB::sysDescr.0 = STRING: Linux server1 2.4.34-pre2 #170 Fri Sep 15 20:10:21 CEST 2006 mips
  SNMPv2-MIB::sysObjectID.0 = OID: NET-SNMP-TC::linux
  DISMAN-EVENT-MIB::sysUpTimeInstance = Timeticks: (706980) 1:57:49.80

==== Ethereal/Wireshark Notes ====

Note to [http://www.wireshark.org/ Wireshark] users (previously known as ''Ethereal''):

You must use one of these methods in this section for Wireshark
since it won't support the -m and -M options discussed previously.

== See Also ==

Please note the following sections of the FAQ as well:
* [http://www.net-snmp.org/FAQ.html#How_do_I_add_a_MIB_ How do I add a MIB]
* [http://www.net-snmp.org/FAQ.html#How_do_I_add_a_MIB_to_the_tools_ How do I add a MIB to the tools?]
* [http://www.net-snmp.org/FAQ.html#I_m_getting_answers__but_they_re_all_numbers__Why_ I'm getting answers, but they're all numbers. Why?]
* ... (Read the entire [http://www.net-snmp.org/FAQ.html FAQ] Please!)

{{TUT:LIST}}