require 'snmp'

module SNMP
  class OctetString
    def to_date_time
      raise ArgumentError, "not DateAndTime format" if size != 8 and size != 11
      year = self[0].ord * 256 + self[1].ord
      month = self[2].ord
      day = self[3].ord
      hour = self[4].ord
      minutes = self[5].ord
      seconds = self[6].ord
      tenths = self[7].ord
      sprintf("%d-%d-%d,%02d:%02d:%02d.%d", year, month, day, hour, minutes, seconds, tenths)
    end
  end
end

SNMP::Manager.open(:Host => 'localhost', :MibModules => ["HOST-RESOURCES-MIB"]) do |snmp|
  response = snmp.get_value("hrSystemDate.0")
  puts response.to_date_time
end