Class: SNMP::Manager

Inherits:
Object
  • Object
show all
Defined in:
lib/snmp/manager.rb

Overview

SNMP Manager

This class provides a manager for interacting with a single SNMP agent.

Example

require 'snmp'

manager = SNMP::Manager.new(:Host => 'localhost', :Port => 1061)
response = manager.get(["1.3.6.1.2.1.1.1.0", "1.3.6.1.2.1.1.2.0"])
response.each_varbind {|vb| puts vb.inspect}
manager.close

Symbolic Object Names

Symbolic names for SNMP object IDs can be used as parameters to the APIs in this class if the MIB modules are imported and the names of the MIBs are included in the MibModules configuration parameter.

See MIB.varbind_list for a description of valid parameter formats.

The following modules are loaded by default: “SNMPv2-MIB”, “IF-MIB”, “IP-MIB”, “TCP-MIB”, “UDP-MIB”. All of the current IETF MIBs have been imported and are available for loading.

Additional modules may be imported using the MIB class. The current implementation of the importing code requires that the external ‘smidump’ tool is available in your PATH. This tool can be obtained from the libsmi website at www.ibr.cs.tu-bs.de/projects/libsmi/ .

Example

Do this once:

SNMP::MIB.import_module(MY_MODULE_FILENAME, MIB_OUTPUT_DIR)

Include your module in MibModules each time you create a Manager:

SNMP::Manager.new(:Host => 'localhost', :MibDir => MIB_OUTPUT_DIR,
                  :MibModules => ["MY-MODULE-MIB", "SNMPv2-MIB", ...])

Constant Summary collapse

DefaultConfig =

Default configuration. Individual options may be overridden when the Manager is created.

{
:Host => 'localhost',
:Port => 161,
:Community => 'public',
:WriteCommunity => nil,
:Version => :SNMPv2c,
:Timeout => 1,
:Retries => 5,
:Transport => UDPTransport,
:MaxReceiveBytes => 8000,
:MibDir => MIB::DEFAULT_MIB_PATH,
:MibModules => ["SNMPv2-MIB", "IF-MIB", "IP-MIB", "TCP-MIB", "UDP-MIB"]}
@@request_id = 
RequestId.new

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(config = {}) ⇒ Manager

Returns a new instance of Manager.



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# File 'lib/snmp/manager.rb', line 150

def initialize(config = {})
    if block_given?
        warn "SNMP::Manager::new() does not take block; use SNMP::Manager::open() instead"
    end
    @config = DefaultConfig.merge(config)
    @config[:WriteCommunity] = @config[:WriteCommunity] || @config[:Community]
    @community = @config[:Community]
    @write_community = @config[:WriteCommunity]
    @snmp_version = @config[:Version]
    @max_bytes = @config[:MaxReceiveBytes]
    @timeout = @config[:Timeout]
    @retries = @config[:Retries]
    @transport = @config[:Transport].new(@config[:Host], @config[:Port])
    @mib = MIB.new
    load_modules(@config[:MibModules], @config[:MibDir])
end

Instance Attribute Details

#config ⇒ Object (readonly)

Retrieves the current configuration of this Manager.



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# File 'lib/snmp/manager.rb', line 143

def config
  @config
end

#mib ⇒ Object (readonly)

Retrieves the MIB for this Manager.



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# File 'lib/snmp/manager.rb', line 148

def mib
  @mib
end

Class Method Details

.open(config = {}) ⇒ Object

Creates a Manager but also takes an optional block and automatically closes the transport connection used by this manager after the block completes.



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# File 'lib/snmp/manager.rb', line 172

def self.open(config = {})
    manager = Manager.new(config)
    if block_given?
        begin
            yield manager
        ensure
            manager.close
        end
    end
end

Instance Method Details

#close ⇒ Object

Close the transport connection for this manager.



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# File 'lib/snmp/manager.rb', line 186

def close
    @transport.close
end

#get(object_list) ⇒ Object

Sends a get request for the supplied list of ObjectId or VarBind objects.

Returns a Response PDU with the results of the request.



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# File 'lib/snmp/manager.rb', line 200

def get(object_list)
    varbind_list = @mib.varbind_list(object_list, :NullValue)
    request = GetRequest.new(@@request_id.next, varbind_list)
    try_request(request)
end

#get_bulk(non_repeaters, max_repetitions, object_list) ⇒ Object

Sends a get-bulk request. The non_repeaters parameter specifies the number of objects in the object_list to be retrieved once. The remaining objects in the list will be retrieved up to the number of times specified by max_repetitions.



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# File 'lib/snmp/manager.rb', line 246

def get_bulk(non_repeaters, max_repetitions, object_list)
    varbind_list = @mib.varbind_list(object_list, :NullValue)
    request = GetBulkRequest.new(
            @@request_id.next,
            varbind_list,
            non_repeaters,
            max_repetitions)
    try_request(request)
end

#get_next(object_list) ⇒ Object

Sends a get-next request for the supplied list of ObjectId or VarBind objects.

Returns a Response PDU with the results of the request.



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# File 'lib/snmp/manager.rb', line 234

def get_next(object_list)
    varbind_list = @mib.varbind_list(object_list, :NullValue)
    request = GetNextRequest.new(@@request_id.next, varbind_list)
    try_request(request)
end

#get_value(object_list) ⇒ Object

Sends a get request for the supplied list of ObjectId or VarBind objects.

Returns a list of the varbind values only, not the entire response, in the same order as the initial object_list. This method is useful for retrieving scalar values.

For example:

SNMP::Manager.open(:Host => "localhost") do |manager|
  puts manager.get_value("sysDescr.0")
end



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# File 'lib/snmp/manager.rb', line 220

def get_value(object_list)
    if object_list.respond_to? :to_ary
        get(object_list).vb_list.collect { |vb| vb.value }
    else
        get(object_list).vb_list.first.value
    end
end

#load_module(name) ⇒ Object 



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# File 'lib/snmp/manager.rb', line 190

def load_module(name)
    @mib.load_module(name)
end

#next_request_id=(request_id) ⇒ Object

Set the next request-id instead of letting it be generated automatically. This method is useful for testing and debugging.



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# File 'lib/snmp/manager.rb', line 321

def next_request_id=(request_id)
    @@request_id.force_next(request_id)
end

#set(object_list) ⇒ Object

Sends a set request using the supplied list of VarBind objects.

Returns a Response PDU with the results of the request.



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# File 'lib/snmp/manager.rb', line 261

def set(object_list)
    varbind_list = @mib.varbind_list(object_list, :KeepValue)
    request = SetRequest.new(@@request_id.next, varbind_list)
    try_request(request, @write_community)
end

#walk(object_list) ⇒ Object

Walks a list of ObjectId or VarBind objects using get_next until the response to the first OID in the list reaches the end of its MIB subtree.

The varbinds from each get_next are yielded to the given block as they are retrieved. The result is yielded as a VarBind when walking a single object or as a VarBindList when walking a list of objects.

Normally this method is used for walking tables by providing an ObjectId for each column of the table.

For example:

SNMP::Manager.open(:Host => "localhost") do |manager|
  manager.walk("ifTable") { |vb| puts vb }
end

SNMP::Manager.open(:Host => "localhost") do |manager|
  manager.walk(["ifIndex", "ifDescr"]) do |index, descr| 
    puts "#{index.value} #{descr.value}"
  end
end

Raises:

  • (ArgumentError) 


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# File 'lib/snmp/manager.rb', line 291

def walk(object_list)
    raise ArgumentError, "expected a block to be given" unless block_given?
    varbind_list = @mib.varbind_list(object_list, :NullValue)
    start_oid = varbind_list.first.name
    last_oid = start_oid
    loop do
        varbind_list = get_next(varbind_list).varbind_list
        first_vb = varbind_list.first
        break if EndOfMibView == first_vb.value 
        stop_oid = first_vb.name
        if stop_oid <= last_oid
            warn "OIDs are not increasing, #{last_oid} followed by #{stop_oid}"
            break
        end
        break unless stop_oid.subtree_of?(start_oid)
        last_oid = stop_oid
        if object_list.respond_to?(:to_str) ||
           object_list.respond_to?(:to_varbind)
        then
            yield first_vb
        else
            yield varbind_list
        end
    end
end