SNMP::Effective - An effective SNMP-information-gathering module

1.0801

    use SNMP::Effective;

    my $snmp = SNMP::Effective->new(
        max_sessions => $NUM_POLLERS,
        master_timeout => $TIMEOUT_SECONDS,
    );

    $snmp->add(
        dest_host => $ip,
        callback => sub { store_data() },
        get => [ '1.3.6.1.2.1.1.3.0', 'sysDescr' ],
    );

    # lather, rinse, repeat

    # retrieve data from all hosts
    $snmp->execute;

This module collects information, over SNMP, from many hosts and many OIDs, really fast.

It is a wrapper around the facilities of SNMP.pm, which is the Perl interface to the C libraries in the SNMP package. Advantages of using this module include:

Simple configuration

The data structures required by SNMP are complex to set up before polling, and parse for results afterwards. This module provides a simpler interface to that configuration by accepting just a list of SNMP OIDs or leaf names.

Parallel execution

Many users are not aware that SNMP can poll devices asynchronously using a callback system. By specifying your callback routine as in the "SYNOPSIS" section above, many network devices can be polled in parallel, making operations far quicker. Note that this does not use threads.

It's fast

To give one example, SNMP::Effective can walk, say, eight indexed OIDs (port status, errors, traffic, etc) for around 300 devices (that's 8500 ports) in under 30 seconds. Storage of that data might take an additional 10 seconds (depending on whether it's to RAM or disk). This makes polling/monitoring your network every five minutes (or less) no problem at all.

The interface to this module is simple, with few options. The sections below detail everything you need to know.

The method arguments are very flexible. Any of the below acts as the same:

    $obj->method(MyKey => $value);
    $obj->method(my_key => $value);
    $obj->method(My_Key => $value);
    $obj->method(mYK__EY => $value);

Get/Set the master timeout

Get/Set the number of max session

Returns a list containing all the hosts.

Returns a hash with the default args

Returns a ref to the default callback sub-routine.

Returns a value for the default heap.

This is the object constructor, and returns a SNMP::Effective object.

max_sessions

Maximum number of simultaneous SNMP sessions.

master_timeout

Maximum number of seconds before killing execute.

All other arguments are passed on to $snmp_effective->add( ... ).

Adding information about what SNMP data to get and where to get it.

dest_host

Either a single host, or an array-ref that holds a list of hosts. The format is whatever SNMP can handle.

arg

A hash-ref of options, passed on to SNMP::Session.

callback

A reference to a sub which is called after each time a request is finished.

heap

This can hold anything you want. By default it's an empty hash-ref.

get / getnext / walk

Either "oid object", "numeric oid", SNMP::Varbind SNMP::VarList or an array-ref containing any combination of the above.

set

Either a single SNMP::Varbind or a SNMP::VarList or an array-ref of any of the above.

This can be called with many different combinations, such as:

dest_host / any other argument

This will make changes per dest_host specified. You can use this to change arg, callback or add OIDs on a per-host basis.

get / getnext / walk / set

The OID list submitted to add will be added to all dest_host, if no dest_host is specified.

arg / callback

This can be used to alter all hosts' SNMP arguments or callback method.

This method starts setting and/or getting data. It will run as long as necessary, or until master_timeout seconds has passed. Every time some data is set and/or retrieved, it will call the callback-method, as defined globally or per host.

Takes two arguments: One OID to match against, and the OID to match.

    match_oid("1.3.6.10",   "1.3.6");    # return 10
    match_oid("1.3.6.10.1", "1.3.6");    # return 10.1
    match_oid("1.3.6.10",   "1.3.6.11"); # return undef

Inverse of make_numeric_oid: Takes a list of mib-object strings, and turns them into numeric format.

 make_numeric_oid("sysDescr"); # return .1.3.6.1.2.1.1.1

Takes a list of numeric OIDs and turns them into an mib-object string.

    make_name_oid("1.3.6.1.2.1.1.1"); # return sysDescr

When SNMP is done collecting data from a host, it calls a callback method, provided by the Callback => sub{} argument. Here is an example of a callback method:

 sub my_callback {
     my($host, $error) = @_

     if($error) {
         warn "$host failed with this error: $error"
         return;
     }

     my $data = $host->data;

     for my $oid (keys %$data) {
         print "$host returned oid $oid with this data:\n";

         print join "\n\t",
               map { "$_ => $data->{$oid}{$_}" }
                   keys %{ $data->{$oid}{$_} };
         print "\n";
     }
 }

Debugging is enabled through setting the environment variable

    SNMP_EFFECTIVE_DEBUG=1 perl myscript.pl

It will print the debug information to STDERR.

walk

SNMP::Effective doesn't really do a SNMP native "walk". It makes a series of "getnext", which is almost the same as SNMP's walk.

set

If you want to use SNMP SET, you have to build your own varbind:

 $varbind = SNMP::VarBind($oid, $iid, $value, $type);
 $effective->add( set => $varbind );

Jan Henning Thorsen, <pm at flodhest.net>

Please report any bugs or feature requests to bug-snmp-effective at rt.cpan.org, or through the web interface at http://rt.cpan.org/NoAuth/ReportBug.html?Queue=SNMP-Effective. I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.

Various contributions by Oliver Gorwits.

Sigurd Weisteen Larsen contributed with a better locking mechanism.

Copyright 2007 Jan Henning Thorsen, all rights reserved.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.