Mike Mitchell wrote:
As the author of SNMP_util.pm I strongly disagree that the problem
lies with the SNMP_util module.
The SNMP_util.pm module does not do any SNMP queries on its own,
rather it calls Simon Leinen's SNMP_Session module to do all socket
I/O. In private email I suggested Brandon Miller use 16-bit SNMP
request IDs (--use-16bit on cfgmaker) and to enable
'avoid_negative_request_ids', but he did not respond.
Mike Mitchell
*From:* [email protected]
[mailto:[email protected]] *On Behalf Of *Brandon Miller
*Sent:* Friday, January 22, 2010 10:32 AM
*To:* Steve Shipway
*Cc:* [email protected]
*Subject:* Re: [mrtg] SNMPWALK Problem for 1.3.6.1.2.1.1 on
cross-compiled mrtg (openwrt mipsbe)
Steve Shipway wrote:
I'm attempting to cross-compile mrtg for openwrt on a mipsbe processor.
...
SNMPv1_Session (remote host: "10.255.255.253" [10.255.255.253].161)
community: "public"
request ID: -552632565
PDU bufsize: 8000 bytes
timeout: 2s
retries: 5
backoff: 1)
at /usr/share/mrtg/bin/../lib/mrtg2/SNMP_util.pm line 631
SNMPWALK Problem for 1.3.6.1.2.1.1 on [email protected]:::::1:v4only
<mailto:[email protected]:::::1:v4only>
at ./cfgmaker line 950
...
r...@openwrt:/usr/share/mrtg/lib/mrtg2# snmpwalk -c public -v 1
10.255.255.253 1.3.6.1.2.1.1
...
iso.3.6.1.2.1.1.1.0 = STRING: "router"
iso.3.6.1.2.1.1.2.0 = OID: iso.3.6.1.4.1.14988.1
iso.3.6.1.2.1.1.3.0 = Timeticks: (46821500) 5 days, 10:03:35.00
iso.3.6.1.2.1.1.4.0 = STRING: "test-box"
iso.3.6.1.2.1.1.5.0 = STRING: "wrtName"
iso.3.6.1.2.1.1.6.0 = STRING: "here"
iso.3.6.1.2.1.1.7.0 = INTEGER: 78
Sounds as if the problem lies in the SNMP_util module, which is part of the MRTG installation. I have no familiarity with your OS but it may be that this module is making some assumptions about SNMP - maybe there are permissions issues on who can listen the UDP responses, for example.
Since snmpwalk works we know the issue is not the agent, but snmpwalk uses different code to SNMP_util.pm.
I'd suggest you direct your investigations to this module, maybe make a small Perl script to use it to make a single SNMP lookup and see if that works?
Steve
Thanks for the responses. I took the easy way out and decided to use
a different monitoring tool. Found that rrd was a pre-compiled
package for my openwrt install. Gave that a try and got it working.
Unfortunately, this project is short-fused and I don't have much time
to troubleshoot the mrtg install...even though I got this far :) I
agree, the problem was probably in SNMP_util.pm. I didn't get too far
in examining that or the packet dumps that I captured. I'm also
wondering if running the perl code on a big endian machine vs a little
endian machine made a difference?
Thanks again
Brandon
I stand corrected. I was debugging late at night. Looking over the
debugging that I managed to do, it seemed to be stuck in SNMP_Session.pm
and not in SNMP_util.pm. Also, while I was just in there looking at it,
I tried cfgmaker again with the fix Mike suggested. I changed
avoid_negative_request_ids as suggested, but didn't seem to help.
Thanks for the suggestion though. I have a feeling that SNMP_Session or
something that it uses is doing something weird with integers that is
different on a big-endian machine....
Brandon
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