class 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 SNMP::MIB#varbind_list for a description of valid parameter formats.
The following modules are loaded by default: “SNMPv2-SMI”, “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', :mib_dir => MIB_OUTPUT_DIR, :mib_modules => ["MY-MODULE-MIB", "SNMPv2-MIB", ...])
Attributes
Retrieves the current configuration of this Manager.
Public Class Methods
Creates a Manager. The following are valid options and their default values.
Note: The upper-case options supported in previous versions of this library are deprecated, but still supported for now. Use at your own risk.
Option Default Value -------------------------------------- :host 'localhost' :port 161 :trap_port 162 :community 'public' :write_community Same as :community :version :SNMPv2c :timeout 1 (timeout units are seconds) :retries 5 :transport UDPTransport :max_recv_bytes 8000 bytes :mib_dir MIB::DEFAULT_MIB_PATH :mib_modules SNMPv2-SMI, SNMPv2-MIB, IF-MIB, IP-MIB, TCP-MIB, UDP-MIB :use_IPv6 false, unless :host is formatted like an IPv6 address
Use {:version => :SNMPv1} for SNMP v1. SNMP v3 is not supported.
# File lib/snmp/manager.rb, line 176 def initialize(options = {}) if block_given? warn "SNMP::Manager.new() does not take block; use SNMP::Manager.open() instead" end config = Config.new(options) @host = config.host @port = config.port @trap_port = config.trap_port @community = config.community @write_community = config.write_community @snmp_version = config.version @timeout = config.timeout @retries = config.retries @transport = config.create_transport @max_bytes = config.max_recv_bytes @mib = MIB.new load_modules(config.mib_modules, config.mib_dir) @config = config.applied_config end
Creates a Manager but also takes an optional block and automatically closes the transport connection used by this manager after the block completes.
# File lib/snmp/manager.rb, line 201 def self.open(config = {}) manager = Manager.new(config) if block_given? begin yield manager ensure manager.close end end end
Public Instance Methods
Close the transport connection for this manager.
# File lib/snmp/manager.rb, line 215 def close @transport.close end
Helper method for building VarBindList for trap and inform requests.
# File lib/snmp/manager.rb, line 376 def create_trap_vb_list(sys_up_time, trap_oid, object_list) vb_args = @mib.varbind_list(object_list, :KeepValue) uptime_vb = VarBind.new(SNMP::SYS_UP_TIME_OID, TimeTicks.new(sys_up_time.to_int)) trap_vb = VarBind.new(SNMP::SNMP_TRAP_OID_OID, @mib.oid(trap_oid)) VarBindList.new([uptime_vb, trap_vb, *vb_args]) end
Sends a get request for the supplied list of ObjectId or VarBind objects.
Returns a Response PDU with the results of the request.
# File lib/snmp/manager.rb, line 229 def get(object_list) varbind_list = @mib.varbind_list(object_list, :NullValue) request = GetRequest.new(@@request_id.next, varbind_list) try_request(request) end
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.
# File lib/snmp/manager.rb, line 275 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
Sends a get-next request for the supplied list of ObjectId or VarBind objects.
Returns a Response PDU with the results of the request.
# File lib/snmp/manager.rb, line 263 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
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
# File lib/snmp/manager.rb, line 249 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
Sends an inform request using the supplied varbind list.
sys_up_time: An integer respresenting the number of hundredths of a second that this system has been up.
trap_oid: An ObjectId or String with the OID identifier for this inform request.
object_list: A list of additional varbinds to send with the inform.
# File lib/snmp/manager.rb, line 367 def inform(sys_up_time, trap_oid, object_list=[]) vb_list = create_trap_vb_list(sys_up_time, trap_oid, object_list) request = InformRequest.new(@@request_id.next, vb_list) try_request(request, @community, @host, @trap_port) end
# File lib/snmp/manager.rb, line 219 def load_module(name) @mib.load_module(name) end
# File lib/snmp/manager.rb, line 476 def load_modules(module_list, mib_dir) module_list.each { |m| @mib.load_module(m, mib_dir) } end
Set the next request-id instead of letting it be generated automatically. This method is useful for testing and debugging.
# File lib/snmp/manager.rb, line 472 def next_request_id=(request_id) @@request_id.force_next(request_id) end
Sends a set request using the supplied list of VarBind objects.
Returns a Response PDU with the results of the request.
# File lib/snmp/manager.rb, line 290 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
Sends an SNMPv1 style trap.
enterprise: The enterprise OID from the IANA assigned numbers (www.iana.org/assignments/enterprise-numbers) as a String or an ObjectId.
agent_addr: The IP address of the SNMP agent as a String or IpAddress.
generic_trap: The generic trap identifier. One of :coldStart, :warmStart, :linkDown, :linkUp, :authenticationFailure, :egpNeighborLoss, or :enterpriseSpecific
specific_trap: An integer representing the specific trap type for an enterprise-specific trap.
timestamp: An integer respresenting the number of hundredths of a second that this system has been up.
object_list: A list of additional varbinds to send with the trap.
For example:
Manager.open(:Version => :SNMPv1) do |snmp| snmp.trap_v1( "enterprises.9", "10.1.2.3", :enterpriseSpecific, 42, 12345, [VarBind.new("1.3.6.1.2.3.4", Integer.new(1))]) end
# File lib/snmp/manager.rb, line 329 def trap_v1(enterprise, agent_addr, generic_trap, specific_trap, timestamp, object_list=[]) vb_list = @mib.varbind_list(object_list, :KeepValue) ent_oid = @mib.oid(enterprise) agent_ip = IpAddress.new(agent_addr) specific_int = Integer(specific_trap) ticks = TimeTicks.new(timestamp) trap = SNMPv1_Trap.new(ent_oid, agent_ip, generic_trap, specific_int, ticks, vb_list) send_request(trap, @community, @host, @trap_port) end
Sends an SNMPv2c style trap.
sys_up_time: An integer respresenting the number of hundredths of a second that this system has been up.
trap_oid: An ObjectId or String with the OID identifier for this trap.
object_list: A list of additional varbinds to send with the trap.
# File lib/snmp/manager.rb, line 350 def trap_v2(sys_up_time, trap_oid, object_list=[]) vb_list = create_trap_vb_list(sys_up_time, trap_oid, object_list) trap = SNMPv2_Trap.new(@@request_id.next, vb_list) send_request(trap, @community, @host, @trap_port) end
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
The index_column identifies the column that will provide the index for each row. This information is used to deal with “holes” in a table (when a row is missing a varbind for one column). A missing varbind is replaced with a varbind with the value NoSuchInstance.
Note: If you are getting back rows where all columns have a value of NoSuchInstance then your index column is probably missing one of the rows. Choose an index column that includes all indexes for the table.
# File lib/snmp/manager.rb, line 416 def walk(object_list, index_column=0) raise ArgumentError, "expected a block to be given" unless block_given? vb_list = @mib.varbind_list(object_list, :NullValue) raise ArgumentError, "index_column is past end of varbind list" if index_column >= vb_list.length is_single_vb = object_list.respond_to?(:to_str) || object_list.respond_to?(:to_varbind) start_list = vb_list start_oid = vb_list[index_column].name last_oid = start_oid loop do vb_list = get_next(vb_list).vb_list index_vb = vb_list[index_column] break if EndOfMibView == index_vb.value stop_oid = index_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 is_single_vb yield index_vb else vb_list = validate_row(vb_list, start_list, index_column) yield vb_list end end end
Private Instance Methods
Wait until response arrives. Ignore responses with mismatched IDs; these responses are typically from previous requests that timed out or almost timed out.
# File lib/snmp/manager.rb, line 514 def get_response(request) begin data = @transport.recv(@max_bytes) message = Message.decode(data, @mib) response = message.pdu end until request.request_id == response.request_id response end
# File lib/snmp/manager.rb, line 504 def send_request(request, community, host, port) message = Message.new(@snmp_version, community, request) @transport.send(message.encode, host, port) end
# File lib/snmp/manager.rb, line 488 def try_request(request, community=@community, host=@host, port=@port) (@retries + 1).times do |n| send_request(request, community, host, port) begin Timeout.timeout(@timeout) do return get_response(request) end rescue Timeout::Error # no action - try again rescue => e warn e.to_s end end raise RequestTimeout, "host #{config[:host]} not responding", caller end
Helper method for walk. Checks all of the VarBinds in vb_list to make sure that the row indices match. If the row index does not match the index column, then that varbind is replaced with a varbind with a value of NoSuchInstance.
# File lib/snmp/manager.rb, line 451 def validate_row(vb_list, start_list, index_column) start_vb = start_list[index_column] index_vb = vb_list[index_column] row_index = index_vb.name.index(start_vb.name) vb_list.each_index do |i| if i != index_column expected_oid = start_list[i].name + row_index if vb_list[i].name != expected_oid vb_list[i] = VarBind.new(expected_oid, NoSuchInstance).with_mib(@mib) end end end vb_list end
# File lib/snmp/manager.rb, line 482 def warn(message) trace = caller(2) location = trace[0].sub(/:in.*/, '') Kernel::warn "#{location}: warning: #{message}" end