check-windows-port-listening.rb

check-windows-port-listening.rb

#! /usr/bin/env ruby
#
#   check-windows-port-listening.rb
#
# DESCRIPTION:
#   Check to see which ports are listening, using netstat.
#   First draft.
#
# OUTPUT:
#   plain text
#
# PLATFORMS:
#   Windows
#
# DEPENDENCIES:
#   gem: sensu-plugin
#
# USAGE:
#   check-windows-port-listening.rb -ports 80,443,3389
#
# NOTES:
#   Uses netstat binary. 
#
# LICENSE:
#   Copyright 2017 <james@absolutejam.co.uk>
#   Released under the same terms as Sensu (the MIT license); see LICENSE for details.
#
require 'sensu-plugin/check/cli'

class CheckListeningPorts < Sensu::Plugin::Check::CLI
  option :ports,
         short: '-p PORT',
         long: '--port PORT',
         :required => true,
         proc: proc { |a| a.split(',') }

  def initialize
    super
    @listening_ports = []
    @missing_ports = []
  end

  def listening_ports
    `netstat -afo`.split("\n").drop(4).each do |line|
      begin
        protocol, local, foreign, state, pid = line.chomp.lstrip.split(/\s+/)
        # Match ipv4 with port (0.0.0.0:0)
        localip, localport = local.match(/\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\:(\d+)/).to_a
        next if /\S/ !~ line
        next if !localport
        next if config[:ports] && !config[:ports].include?(localport)
        next if state != 'LISTENING'
        next if @listening_ports.include?(localport)
      rescue
        unknown "malformed line from netstat: #{line}"
      end
      @listening_ports << localport
    end

    config[:ports].each do |p|
      @missing_ports << p if !@listening_ports.include?(p)
    end
  end

  def usage_summary
    missing = (@missing_ports).join(', ')
    "The following ports are NOT listening: #{missing}"
  end

  def run
    listening_ports
    critical usage_summary unless @missing_ports.empty?
    ok "All specified ports are listening"
  end
end