Jan Henning Thorsen


Mojo::SNMP - Run SNMP requests with Mojo::IOLoop




  use Mojo::SNMP;
  my $snmp = Mojo::SNMP->new;
  my @response;

  $snmp->on(response => sub {
    my($snmp, $session, $args) = @_;
    warn "Got response from $args->{hostname} on $args->{method}(@{$args->{request}})...\n";
    push @response, $session->var_bind_list;

    community => 'public', # v1, v2c
    username => 'foo', # v3
    version => 'v2c', # v1, v2c or v3

  $snmp->prepare('', get_next => ['']);
  $snmp->prepare('localhost', { version => 'v3' }, get => ['']);

  # start the IOLoop unless it is already running
  $snmp->wait unless $snmp->ioloop->is_running;


You should use this module if you need to fetch data from many SNMP servers really fast. The module does its best to not get in your way, but rather provide a simple API which allow you to extract information from multiple servers at the same time.

This module use Net::SNMP and Mojo::IOLoop to fetch data from hosts asynchronous. It does this by using a custom dispatcher, Mojo::SNMP::Dispatcher, which attach the sockets created by Net::SNMP directly into the ioloop reactor.

If you want greater speed, you should check out Net::SNMP::XS and make sure Mojo::Reactor::EV is able to load.

Mojo::SNMP is supposed to be a replacement for a module I wrote earlier, called SNMP::Effective. Reason for the rewrite is that I'm using the framework Mojolicious which includes an awesome IO loop which allow me to do cool stuff inside my web server.


Net::SNMP provide methods to retrieve data from the SNMP agent, such as get_next(). It is possible to add custom methods if you find yourself doing the same complicated logic over and over again. Such methods can be added using "add_custom_request_method".

There are two custom methods bundled to this package:

  • bulk_walk

    This method will run get_bulk_request until it receives an oid which does not match the base OID. maxrepetitions is set to 10 by default, but could be overrided by maxrepetitions inside %args.


      $self->prepare('' => { maxrepetitions => 25 }, bulk_walk => [$oid, ...]);
  • walk

    This method will run get_next_request until the next oid retrieved does not match the base OID or if the tree is exhausted.



  $self->on(error => sub {
    my($self, $str, $session, $args) = @_;

Emitted on errors which may occur. $session is set if the error is a result of a Net::SNMP method, such as get_request().

See "response" for $args description.


  $self->on(finish => sub {
    my $self = shift;

Emitted when all hosts have completed.


  $self->on(response => sub {
    my($self, $session, $args) = @_;

Called each time a host responds. The $session is the current Net::SNMP object. $args is a hash ref with the arguments given to "prepare", with some additional information:

    method => $str, # get, get_next, ...
    request => [$oid, ...],
    # ...


  $self->on(timeout => sub {
    my $self = shift;

Emitted if wait has been running for more than "master_timeout" seconds.



How many hosts to fetch data from at once. Default is 20. (The default may change in later versions)


This attribute holds a hash ref with default arguments which will be passed on to "session" in Net::SNMP. User-submitted %args will be merged with the defaults before being submitted to "prepare". prepare() will filter out and ignore arguments that don't work for the SNMP version.

NOTE: SNMP version will default to "v2c".


How long to run in total before timeout. Note: This is NOT per host but for the complete run. Default is 0, meaning run for as long as you have to.


Holds an instance of Mojo::IOLoop.



  $self->add_custom_request_method(name => sub {
    my($session, %args) = @_;
    # do custom stuff..

This method can be used to add custom Net::SNMP request methods. See the source code for an example on how to do "walk".

NOTE: This method will also replace any method, meaning the code below will call the custom callback instead of "get_next_request" in Net::SNMP.

  $self->add_custom_request_method(get_next => $custom_callback);


  $self->get($host, $args, \@oids, sub {
    my($self, $err, $res) = @_;
    # ...

Will call the callback when data is retrieved, instead of emitting the "response" event.


  $self->get_bulk($host, $args, \@oids, sub {
    my($self, $err, $res) = @_;
    # ...

Will call the callback when data is retrieved, instead of emitting the "response" event. $args is optional.


  $self->get_next($host, $args, \@oids, sub {
    my($self, $err, $res) = @_;
    # ...

Will call the callback when data is retrieved, instead of emitting the "response" event. $args is optional.


  $self = $self->prepare($host, \%args, ...);
  $self = $self->prepare(\@hosts, \%args, ...);
  $self = $self->prepare(\@hosts, ...);
  $self = $self->prepare('*' => ...);
  • $host

    This can either be an array ref or a single host. The "host" can be whatever "session" in Net::SNMP can handle; generally a hostname or IP address.

  • \%args

    A hash ref of options which will be passed directly to "session" in Net::SNMP. This argument is optional. See also "defaults".

  • dot-dot-dot

    A list of key-value pairs of SNMP operations and bindlists which will be given to "prepare". The operations are the same as the method names available in Net::SNMP, but without "_request" at end:


    The special hostname "*" will apply the given operation to all previously defined hosts.


  $self->prepare('' => { version => 'v2c' }, get_next => [$oid, ...]);
  $self->prepare('' => { version => 'v3' }, get => [$oid, ...]);
  $self->prepare(localhost => set => [ $oid => OCTET_STRING, $value, ... ]);
  $self->prepare('*' => get => [ $oid ... ]);

Note: To get the OCTET_STRING constant and friends you need to do:

  use Net::SNMP ':asn1';


  $self->set($host, $args => [ $oid => OCTET_STRING, $value, ... ], sub {
    my($self, $err, $res) = @_;
    # ...

Will call the callback when data is set, instead of emitting the "response" event. $args is optional.


  $self->walk($host, $args, \@oids, sub {
    my($self, $err, $res) = @_;
    # ...

Will call the callback when data is retrieved, instead of emitting the "response" event. $args is optional.


This is useful if you want to block your code: wait() starts the ioloop and runs until "timeout" or "finish" is reached.

  my $snmp = Mojo::SNMP->new;
  $snmp->prepare(...)->wait; # blocks while retrieving data
  # ... your program continues after the SNMP operations have finished.


This library is free software. You can redistribute it and/or modify it under the same terms as Perl itself.


Jan Henning Thorsen - jhthorsen@cpan.org

Joshua Keroes - joshua@cpan.org

Espen Tallaksen