SNMP Library for Ruby

Summary

This library implements SNMP (the Simple Network Management Protocol). It is implemented in pure Ruby, so there are no dependencies on external libraries like net-snmp. You can run this library anywhere that Ruby can run.

See snmplib.rubyforge.org for more info.

This release supports the following:

The GetRequest, GetNextRequest, GetBulkRequest, SetRequest, Response SNMPv1_Trap, SNMPv2_Trap, and Inform PDUs
All of the ASN.1 data types defined by SNMPv1 and SNMPv2c
Sending informs and v1 and v2 traps
Trap handling for informs and v1 and v2 traps
Symbolic OID values (ie. “ifTable” instead of “1.3.6.1.2.1.2.2“) as parameters to the SNMP::Manager API
Includes symbol data files for all current IETF MIBs
Compatibility with both Ruby 1.8 and Ruby 1.9

See the SNMP::Manager, SNMP::TrapListener, and SNMP::MIB classes and the examples below for more details.

Changes

Changes for version 1.1.0:

Added MIB support to ObjectId and Varbind, so that to_s can return symbolic information
Added to_str method to ObjectId to return a numeric OID string (old to_s behavior)
TrapListener can now support multiple community strings

Changes for version 1.0.4:

New option handling and added lower-case versions of all options
Added SNMP::VERSION constant
Experimental support for IPv6
Removed support for installation with setup.rb

Changes for version 1.0.3:

Minor changes to Manager class. The :Transport option may now be an object or a class. Explicity call Timeout.timeout so that a timeout method may be defined in subclasses. Thanks to Eric Monti.

Changes for version 1.0.2:

Internal code changes to make this library compatible with both Ruby 1.8 and Ruby 1.9. Note that an ord() method is now added to the Fixnum class for Ruby 1.8. See the ber.rb file for details.

Changes for version 1.0.1:

Made the host configurable for the TrapListener. Previously defaulted to ‘localhost’.

Changes for version 1.0.0:

Added to_s method to TimeTicks. Displays time in human-readable form instead of just a number. The to_i method can still be used to get the number of ticks.

Installation

You can use RubyGems [rubygems.org/] to install the latest version of the SNMP library.

  gem install snmp

Testing

This library has received limited testing:

The unit tests have been executed with both Ruby 1.8.7 and Ruby 1.9.2 on Mac OS X 10.7.
Basic interoperability testing has been done with the net-snmp tools.

I’m very interested in hearing about successes or failures on other platforms.

Send me an email at hallidave at gmail.com.

Examples

Get Request

Retrieve a system description.

  require 'snmp'
  
  SNMP::Manager.open(:host => 'localhost') do |manager|
      response = manager.get(["sysDescr.0", "sysName.0"])
      response.each_varbind do |vb|
          puts "#{vb.name.to_s}  #{vb.value.to_s}  #{vb.value.asn1_type}"
      end
  end

Set Request

Create a varbind for setting the system name.

  require 'snmp'
  include SNMP

  manager = Manager.new(:host => 'localhost')
  varbind = VarBind.new("1.3.6.1.2.1.1.5.0", OctetString.new("My System Name"))
  manager.set(varbind)
  manager.close

Table Walk

Walk the ifTable.

  require 'snmp'

  ifTable_columns = ["ifIndex", "ifDescr", "ifInOctets", "ifOutOctets"]
  SNMP::Manager.open(:host => 'localhost') do |manager|
      manager.walk(ifTable_columns) do |row|
          row.each { |vb| print "\t#{vb.value}" }
          puts
      end
  end

Get-Next Request

A more difficult way to walk the ifTable.

 
  require 'snmp'
  include SNMP

  Manager.open(:host => 'localhost') do |manager|
      ifTable = ObjectId.new("1.3.6.1.2.1.2.2")
      next_oid = ifTable
      while next_oid.subtree_of?(ifTable)
          response = manager.get_next(next_oid)
          varbind = response.varbind_list.first
          next_oid = varbind.name
          puts varbind.to_s
      end
  end

Get-Bulk Request

Get interface description and admin status for 10 rows of the ifTable.

  require 'snmp'
  include SNMP

  ifDescr_OID = ObjectId.new("1.3.6.1.2.1.2.2.1.2")
  ifAdminStatus_OID = ObjectId.new("1.3.6.1.2.1.2.2.1.7")
  MAX_ROWS = 10
  Manager.open(:host => 'localhost') do |manager|
      response = manager.get_bulk(0, MAX_ROWS, [ifDescr_OID, ifAdminStatus_OID])
      list = response.varbind_list
      until list.empty?
          ifDescr = list.shift
          ifAdminStatus = list.shift
          puts "#{ifDescr.value}    #{ifAdminStatus.value}"
      end
  end

Trap Handling

Log traps to STDOUT.

  require 'snmp'
  require 'logger'

  log = Logger.new(STDOUT)
  m = SNMP::TrapListener.new do |manager|
      manager.on_trap_default do |trap|
          log.info trap.inspect
      end
  end
  m.join

License

This SNMP Library is Copyright © 2004-2011 by David R. Halliday. It is free software. Redistribution is permitted under the same terms and conditions as the standard Ruby distribution. See the COPYING file in the Ruby distribution for details.