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.

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
Compatible with Ruby 1.9 and higher

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

Installation

You can use RubyGems to install the latest version of the SNMP library.

gem install snmp

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 released under the terms of the MIT License.