Reference

NetSNMP::agent(3pm)

Perl extension for the net-snmp agent.

NAME

NetSNMP::agent - Perl extension for the net-snmp agent.

SYNOPSIS

  use NetSNMP::agent;
  my $agent = new NetSNMP::agent('Name' => 'my_agent_name');

DESCRIPTION

This module implements an API set to make a SNMP agent act as a snmp agent, a snmp subagent (using the AgentX subagent protocol) and/or embedded perl-APIs directly within the traditional net-snmp agent daemon.

Also see the tutorial about the genaral Net-SNMP C API, which this module implements in a perl-way, and a perl specific tutorial at:

  http://www.net-snmp.org/tutorial-5/toolkit/

EXAMPLES

Sub-agent example

        use NetSNMP::agent (':all');
        use NetSNMP::ASN qw(ASN_OCTET_STR);
        my $value = "hello world";
        sub myhandler {
            my ($handler, $registration_info, $request_info, $requests) = @_;
            my $request;
            for($request = $requests; $request; $request = $request->next()) {
                my $oid = $request->getOID();
                if ($request_info->getMode() == MODE_GET) {
                    # ... generally, you would calculate value from oid
                    if ($oid == new NetSNMP::OID(".1.3.6.1.4.1.8072.9999.9999.7375.1.0")) {
                        $request->setValue(ASN_OCTET_STR, $value);
                    }
                } elsif ($request_info->getMode() == MODE_GETNEXT) {
                    # ... generally, you would calculate value from oid
                    if ($oid < new NetSNMP::OID(".1.3.6.1.4.1.8072.9999.9999.7375.1.0")) {
                        $request->setOID(".1.3.6.1.4.1.8072.9999.9999.7375.1.0");
                        $request->setValue(ASN_OCTET_STR, $value);
                    }
                } elsif ($request_info->getMode() == MODE_SET_RESERVE1) {
                    if ($oid != new NetSNMP::OID(".1.3.6.1.4.1.8072.9999.9999.7375.1.0")) {  # do error checking here
                        $request->setError($request_info, SNMP_ERR_NOSUCHNAME);
                    }
                } elsif ($request_info->getMode() == MODE_SET_ACTION) {
                    # ... (or use the value)
                    $value = $request->getValue();
                }
            }
        }
        my $agent = new NetSNMP::agent(
                                # makes the agent read a my_agent_name.conf file
                                'Name' => "my_agent_name",
                                'AgentX' => 1
                                );
        $agent->register("my_agent_name", ".1.3.6.1.4.1.8072.9999.9999.7375",
                         \&myhandler);
        my $running = 1;
        while($running) {
                $agent->agent_check_and_process(1);
        }
        $agent->shutdown();

Embedded agent example

        # place this in a .pl file, and then in your snmpd.conf file put:
        #    perl do '/path/to/file.pl';
        use NetSNMP::agent;
        my $agent;
        sub myhandler {
            my ($handler, $registration_info, $request_info, $requests) = @_;
            # ...
        }
        $agent = new NetSNMP::agent(
                                'Name' => 'my_agent_name'
                                );
        $agent->register("my_agent_name", ".1.3.6.1.4.1.8072.9999.9999.7375",
                         \&myhandler);
        $agent->main_loop();

CONSTRUCTOR

    new ( OPTIONS )
        This is the constructor for a new NetSNMP::agent object.
    Possible options are:
        Name    - Name of the agent (optional, defaults to "perl")
                  (The snmp library will read a NAME.conf snmp
                  configuration file based on this argument.)
        AgentX  - Make us a sub-agent (0 = false, 1 = true)
                  (The Net-SNMP master agent must be running first)
        Ports   - Ports this agent will listen on (EG: "udp:161,tcp:161")
    Example:
        $agent = new NetSNMP::agent(
                                 'Name' => 'my_agent_name',
                                 'AgentX' => 1
                                 );

METHODS

    register (NAME, OID, \&handler_routine )
        Registers the callback handler with given OID.
        $agent->register();
        A return code of 0 indicates no error.
    agent_check_and_process ( BLOCKING )
        Run one iteration of the main loop.
        BLOCKING - Blocking or non-blocking call. 1 = true, 0 = false.
        $agent->agent_check_and_process(1);
    main_loop ()
        Runs the agent in a loop. Does not return.
    shutdown ()
        Nicely shuts down the agent or sub-agent.
        $agent->shutdown();

HANDLER CALLBACKS

    handler ( HANDLER, REGISTRATION_INFO, REQUEST_INFO, REQUESTS )
        The handler is called with the following parameters:
        HANDLER                 - FIXME
        REGISTRATION_INFO       - what are the correct meanings of these?
        REQUEST_INFO            -
        REQUESTS                -
    Example handler:
        sub myhandler {
            my ($handler, $reg_info, $request_info, $requests) = @_;
            # ...
        }

The handler subroutine will be called when a SNMP request received by the agent for anything below the registered OID. The handler is passed 4 arguments: $handler, $registration_info, $request_info, $requests. These match the arguments passed to the C version of the same API. Note that they are not entirely complete objects but are functional "enough" at this point in time.

$request_info object functions

    getMode ()
        Returns the mode of the request. See the MODES section for
        list of valid modes.
        $mode = $request->getMode();

$registration_info object functions

    getRootOID ()
        Returns a NetSNMP::OID object that describes the registration
        point that the handler is getting called for (in case you
        register one handler function with multiple OIDs, which should
        be rare anyway)
        $root_oid = $request->getRootOID();

$request object functions

    next ()
        Returns the next request in the list or undef if there is no
        next request.
        $request = $request->next();
    getOID ()
        Returns the oid of the request (a NetSNMP::OID class).
        $oid = $request->getOID();
    setOID (new NetSNMP::OID("someoid"))
        Sets the OID of the request to a passed oid value.  This
        should generally only be done during handling of GETNEXT
        requests.
        $request->setOID(new NetSNMP::OID("someoid"));
    getValue ()
        Returns the value of the request. Used for example when
        setting values.
        $value = $request->getValue();
        FIXME: how to get the type of the value? Is it even available?
               [Wes: no, not yet.]
    setValue ( TYPE, DATA )
        Sets the data to be returned to the daemon.
        Returns 1 on success, 0 on error.
        TYPE - Type of the data. See NetSNMP::ASN for valid types.
        DATA - The data to return.
        $ret = $request->setValue(ASN_OCTET_STR, "test");
    setError ( REQUEST_INFO, ERROR_CODE )
        Sets the given error code for the request. See the ERROR CODES
        section for list of valid codes.
        $request->setError($request_info, SNMP_ERR_NOTWRITABLE);
    getProcessed ()
        The processed flag indicates that a request does not need to
        be dealt with because someone else (a higher handler) has
        dealt with it already.
        $processed = $request->getProcessed();
    setProcessed ( PROCESSED )
        Sets the processed flag flag in the request.  You generally
        should not have to set this yourself.
        PROCESSED - 0 = false, 1 = true
        $request->setProcessed(1);
    getDelegated ()
        If you can handle a request in the background or at a future
        time (EG, you're waiting on a file handle, or network traffic,
        or ...), the delegated flag can be set in the request.  When
        the request is processed in the future the flag should be set
        back to 0 so the agent will know that it can wrap up the
        original request and send it back to the manager.  This has
        not been tested within perl, but it hopefully should work.
        $delegated = $request->getDelegated();
    setDelegated ( DELEGATED )
        Sets the delegated flag.
        DELEGATED - 0 = false, 1 = true
        $request->setDelegated(1);
    getRepeat ()
        The repeat flag indicates that a getbulk operation is being
        handled and this indicates how many answers need to be
        returned.  Generally, if you didn't register to directly
        handle getbulk support yourself, you won't need to deal with
        this value.
        $repeat = $request->getRepeat();
    setRepeat ( REPEAT )
        Sets the repeat count (decrement after answering requests if
        you handle getbulk requests yourself)
        REPEAT -  repeat count FIXME
        $request->setRepeat(5);
    getSourceIp ()
        Gets the IPv4 address of the device making the request to the handler.
        use Socket;
        print "Source: ", inet_ntoa($request->getSourceIp()), "\n";
    getDestIp ()
        Gets the IPv4 address of the destination that the request was sent to.
        use Socket;
        print "Destination: ", inet_ntoa($request->getDestIp()), "\n";

MODES

        MODE_GET
        MODE_GETBULK
        MODE_GETNEXT
        MODE_SET_ACTION
        MODE_SET_BEGIN
        MODE_SET_COMMIT
        MODE_SET_FREE
        MODE_SET_RESERVE1
        MODE_SET_RESERVE2
        MODE_SET_UNDO

ERROR CODES

        SNMP_ERR_NOERROR
        SNMP_ERR_TOOBIG
        SNMP_ERR_NOSUCHNAME
        SNMP_ERR_BADVALUE
        SNMP_ERR_READONLY
        SNMP_ERR_GENERR
        SNMP_ERR_NOACCESS
        SNMP_ERR_WRONGTYPE
        SNMP_ERR_WRONGLENGTH
        SNMP_ERR_WRONGENCODING
        SNMP_ERR_WRONGVALUE
        SNMP_ERR_NOCREATION
        SNMP_ERR_INCONSISTENTVALUE
        SNMP_ERR_RESOURCEUNAVAILABLE
        SNMP_ERR_COMMITFAILED
        SNMP_ERR_UNDOFAILED
        SNMP_ERR_AUTHORIZATIONERROR
        SNMP_ERR_NOTWRITABLE

AUTHOR

Please mail the [email protected] mailing list for help, questions or comments about this module.

Module written by:
Wes Hardaker <[email protected]>

Documentation written by:
Toni Willberg <[email protected]>
Wes Hardaker <[email protected]>

SEE ALSO

NetSNMP::OID(3), NetSNMP::ASN(3), perl(1).

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