[mrtg] Final: FreeBSD Ports: MRTG + Nagios + Net-SNMP + p5-*

Mike Mitchell Mike.Mitchell at sas.com
Tue Apr 10 00:22:10 CEST 2007

SNMP_util.pm is a wrapper for SNMP_Session.pm.  SNMP_util.pm will restrict source queries to a specific VIP, however it does not know about ".snmp-dis/snmp.conf".
Here is a part of the README.SNMP_util file shipped with SNMP_util.pm:

  The port parameter was recently augmented to allow the specification of
  the IP address (or hostname) and port of the machine doing the query in
  addition to the IP address (or hostname) and port of the machine being
  queried.  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 is further broken down
  into "remote_port!local_address!local_port".  Here are some examples:

    somehost:161!!4000  use and port 4000 as source
    somehost:!          use as source
    somehost:!!4000                use port 4000 as source

  Most people will only need to use the first form ("somehost"). 

In the previous text "recently" is sometime before 2001.

Over a year ago, in January of 2006, MRTG version 2.13.0 was released.  That version was the first version of MRTG to include support for SNMPv3.  The support for SNMPv3 is derived from Net::SNMP, using another wrapper (Net_SNMP_util.pm). Net_SNMP_util.pm has the same API as SNMP_util.pm.  Since it calls Net::SNMP->session directly, if Net::SNMP supports the ".snmp-dis/snmp.conf" file, then Net_SNMP_util.pm supports the ".snmp-dis/snmp.conf" file.

I do not see any reference to a "snmp.conf" file in the documentation for Net::SNMP, http://search.cpan.org/~dtown/Net-SNMP-5.2.0/lib/Net/SNMP.pm  Maybe you're confusing the Net-SNMP (http://www.net-snmp.org) suite of applications with the CPAN perl module "Net::SNMP".

Mike Mitchell
SAS Institute Inc.
Mike.Mitchell at sas.com
(919) 531-6793

-----Original Message-----
From: mrtg-bounces at lists.oetiker.ch [mailto:mrtg-bounces at lists.oetiker.ch] On Behalf Of Brian A. Seklecki
Sent: Monday, April 09, 2007 5:32 PM
To: mrtg at lists.oetiker.ch
Subject: [mrtg] Final: FreeBSD Ports: MRTG + Nagios + Net-SNMP + p5-*

Regarding original bug report in 2006:

"I can't tell the MRTG to source queries form a specific VIP on the 
utility box by setting:

# more .snmp-dis/snmp.conf

The PERL POD SNMP_Util doesn't seem to honor these the way the Net-SNMP 
CLI/lib/p5-Net-SNMP does, thus I can't create system-service abstraction. 
Plus, it complicates firewall rules!"

Conclusion: For the record, MRTG does not and can not use Net::SNMP, it 
uses SNMP::Util and SNMP::Session instead.

If one needs a network resource graphing solution and system-service 
abstraction is a priority (HA/Load Balance), then consider a system that 
uses the Net-SNMP libraries.

 	-lava (Brian A. Seklecki - Pittsburgh, PA, USA)

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