snmp__if plugin does not work if server only supports 32 bit counters

[pneu]

The plugin actually supports 32 bit counter as well as 64 bit counter. However, if the snmp server you are connecting to does not support 64 bit byte counters, snmp__if fails.

When I tried to the snmp server which supports only 32 bit counter, the plugin returned as follows:
#munin-run snmp_hostname_if_1
recv.value noSuchObject
send.value noSuchObject

Here is an example of problems I found in the code.

# from line 244
if (defined ($response = $session->get_single($ifEntryIn64Octets) ||
                  $session->get_single($ifEntryInOctets))) {
    print "recv.value ", $response, "\n";
}

In these lines, "$session->get_single($ifEntryIn64Octets" is supposed to return undefined value if the server doesn't support 64 bit counter. However, it actually returns "noSuchObject".

So, these lines should be fixed like this:

if (defined($response = $session->get_single($ifEntryIn64Octets))){
 if ($response eq 'noSuchObject'){
  # 64 bit counter is not supported
  $response = $session->get_single($ifEntryInOctets);
 }
} else {
 # No response
 $response = 'U';
}
print "recv.value ", $response, "\n";

# The information about my environment

Description: Ubuntu 10.04.3 LTS
Release: 10.04

munin-node:
  Installed: 1.4.4-1ubuntu1
  Candidate: 1.4.4-1ubuntu1
  Version table:
 *** 1.4.4-1ubuntu1 0

[pneu (pneu)]

I found this topic should be discussed at the original munin site. So, I'll work on this bug there.

[Dave Walker (davewalker)]

@tome, please can you link to where it is being discussed upstream?

Thanks.

[pneu (pneu)]

Here's the link to the thread I posted in Munin site.
http://munin-monitoring.org/ticket/1143

I also drafted a patch and posted it.

[Stefan Leitner (sleitner-i)]

There is a second bug, if the snmp server doesn't support the alias name entry (1.3.6.1.2.1.31.1.1.1.18.x) of the SNMPv2 , the function returns "noSuchObject"

# from line 162
my $alias = $session->get_single($ifEntryAlias) ||
    $session->get_single($ifEntryDescr) ||
    "Interface $iface";

# a possible fix:
my $alias = $session->get_single($ifEntryAlias);
if ($alias eq 'noSuchObject'){
    $alias = $session->get_single($ifEntryDescr) ||
    "Interface $iface";
}

[Stefan Leitner (sleitner-i)]

I have to correct myself, the fix should be:

    my $alias = $session->get_single($ifEntryAlias);
    if ((!(defined ($alias))) or ($alias eq 'noSuchObject')){
        $alias = $session->get_single($ifEntryDescr) || "Interface $iface";
    }

[Clint Byrum (clint-fewbar)]

Excerpts from Stefan Leitner's message of Thu Mar 01 11:28:55 UTC 2012:
> There is a second bug, if the snmp server doesn't support the alias name
> entry (1.3.6.1.2.1.31.1.1.1.18.x) of the SNMPv2 , the function returns
> "noSuchObject"
>

Stefan, perhaps you should report this bug separately?