SNMP Library for EventMachine¶ ↑

Summary¶ ↑

This gem extends Ruby-SNMP to use the asynchronous EventMachine library for added performance and scalability. This allows code to scale monitoring applications to access a very high number of devices without the need for complex asynchronous I/O handling.

Features¶ ↑

Version 0.2.1 supports:

• SNMP v1 and v2 only

• SNMP Get, GetNext, GetBulk (v2 only), Set, and Walk requests.

• Ability to query/set/walk multiple OIDs in parallel.

Future revisions of this library may support:

• Ability to act as an SNMP agent, responding to external queries.

• Ability to send/receive SNMP traps

There are no plans to support SNMP v3.

Acknowledgements¶ ↑

• The SNMP packet processing is handled by the Ruby-SNMP library, by David Halliday

• EventMachine, by Francis Cianfrocca and Aman Gupta

• All the helpful folks on the Freenode #eventmachine channel

Examples¶ ↑

A few definitions:

OID_SYSTEM = "1.3.6.1.2.1.1"
OID_SYSNAME = "1.3.6.1.2.1.1.5.0"
OID_SYSLOCATION = "1.3.6.1.2.1.1.6.0"

A simple SNMP-GET:

EM.run {
  snmp = SNMP4EM::Manager.new(:host => "192.168.1.1", :version => :SNMPv1)

  request = snmp.get([OID_SYSNAME, OID_SYSLOCATION])

  request.callback do |response|
    puts "System name = #{response[OID_SYSNAME]}"
    puts "System location = #{response[OID_SYSLOCATION]}"
  end

  request.errback do |error|
    puts "GET got error #{error}"
  end
}

A simple SNMP-GETNEXT:

EM.run {
  snmp = SNMP4EM::Manager.new(:host => "192.168.1.1")

  request = snmp.getnext(OID_SYSNAME)

  request.callback do |response|
    r = response[OID_SYSNAME]
    puts "The next OID is #{r[0]}, the next value is #{r[1]}"
  end

  request.errback do |error|
    puts "GETNEXT got error #{error}"
  end
}

A simple SNMP-SET:

EM.run {
  snmp = SNMP4EM::Manager.new(:host => "192.168.1.1")

  request = snmp.set({OID_SYSNAME => "My System Name", OID_SYSLOCATION => "My System Location"})

  request.callback do |response|
    if (response[OID_SYSNAME] == true)
      puts "System name set successful"
    else
      puts "System name set unsuccessful: #{response[OID_SYSNAME]}"
    end

    if (response[OID_SYSLOCATION] == true)
      puts "System location set successful"
    else
      puts "System location set unsuccessful: #{response[OID_SYSLOCATION]}"
    end
  end

  request.errback do |error|
    puts "SET got error #{error}"
  end
}

A simple SNMP-WALK:

EM.run {
  snmp = SNMP4EM::Manager.new(:host => "192.168.1.1")

  request = snmp.walk(OID_SYSTEM)

  request.callback do |response|
    if (response[OID_SYSTEM].is_a? Array)
      response[OID_SYSTEM].each do |vb|
        puts "#{vb[0]} = #{vb[1]}"
      end
    else
      puts "Got error: #{response[OID_SYSTEM]}"
    end
  end

  request.errback do |error|
    puts "WALK got error #{error}"
  end
}

A simple SNMP-GET-BULK:

EM.run {
  snmp = SNMP4EM::Manager.new(:host => "192.168.1.1")

  request = snmp.getbulk(OID_SYSTEM)

  request.callback do |response|
    if (response[OID_SYSTEM].is_a? Array)
      response[OID_SYSTEM].each do |vb|
        puts "#{vb[0]} = #{vb[1]}"
      end
    else
      puts "Got error: #{response[OID_SYSTEM]}"
    end
  end

  request.errback do |error|
    puts "GET-BULK got error #{error}"
  end
}

Change Log¶ ↑

Version 0.2.1:

• Code cleanups, speed boosts

Version 0.2.0:

• Added support for SNMPv2, including GET-BULK operations

Version 0.1.0:

• Initial deployment, ability to run get/getnext/set/walk requests in parallel

Credits¶ ↑

Author: Norman Elton normelton@gmail.com