#!/usr/bin/env ruby
#
# Wildcard-script to monitor network port usage using netstat. To monitor a
# port, link port_<service> to this file. E.g. This plugin shall run by root user
#
#    ln -s /usr/share/munin/node/plugins-auto/port_ /etc/munin/node.d/port_www
#
# ...will monitor www connections. Services are those listed in
# /etc/services. Case service is not listed the numeric value shall be passed
#
# Author: Luis García Acosta
# V 1.0
# Date Tue April 12 09:20:21 CET 2011

require 'rubygems'
require 'munin'

SERVICE   = $0.split('_').last
SERVICE_F = '/etc/services'.freeze
PORT      = SERVICE =~ /^\d+(\.\d+){0,1}$/ ? SERVICE : `grep #{SERVICE} #{SERVICE_F}`.split("\t\t")[1].split('/')[0]

class PortMonit < Munin::Plugin
  graph_attributes "#{SERVICE} port usage, known as #{PORT}",
                   category: 'network',
                   info: 'This graph shows connection split by the state of the socket.',
                   vlabel: 'Current connections'

  declare_field :ESTABLISHED,
                label: 'Established', draw: :AREA,
                type: :GAUGE, min: 0

  declare_field :CLOSE_WAIT,
                label: 'Waiting close', draw: :STACK,
                type: :GAUGE, min: 0

  declare_field :TIME_WAIT,
                label: 'Waiting after close', draw: :STACK,
                type: :GAUGE, min: 0

  declare_field :CLOSING,
                label: 'Closing', draw: :STACK,
                type: :GAUGE, min: 0

  declare_field :LAST_ACK,
                label: 'Waiting for acknowledgement', draw: :STACK,
                type: :GAUGE, min: 0

  declare_field :FIN_WAIT_1,
                label: 'Socket closed, connection shutting down', draw: :STACK,
                type: :GAUGE, min: 0

  declare_field :FIN_WAIT_2,
                label: 'Connection closed, Socket still waiting', draw: :STACK,
                type: :GAUGE, min: 0

  def retrieve_values
    @_netstat = `netstat -n -P tcp | egrep "\.#{PORT} "`.split("\n")

    { ESTABLISHED: count(@_netstat, 'ESTABLISHED'),
      CLOSE_WAIT: count(@_netstat, 'CLOSE_WAIT'),
      CLOSING: count(@_netstat, 'CLOSING'),
      LAST_ACK: count(@_netstat, 'LAST_ACK'),
      FIN_WAIT_1: count(@_netstat, 'FIN_WAIT_1'),
      FIN_WAIT_2: count(@_netstat, 'FIN_WAIT_2'),
      TIME_WAIT: count(@_netstat, 'TIME_WAIT') }
  end

  private

  def count(source, regex)
    @_result = 0

    source.each { |obj| @_result += 1 if obj.match(regex) }

    @_result
  end
end

PortMonit.new.run