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#!/usr/bin/env ruby


netstat_s revision 6 (Nov 2013)

This plugin shows various statistics from 'netstat -s'

Required privileges: none

  Supposed: BSD, Linux (only a few items, see netstat_multi for more)
  Tested:   FreeBSD: 8.2, 8.3, 9.1
            Linux  : Debian 6 (kernel 2.6.32), Arch (kernel 3.11.6), CentOS 6

Author: Artem Sheremet <>

#%# family=auto
#%# capabilities=autoconf suggest


# original filename
PLUGIN_NAME = 'netstat_s_'.freeze

$os = `uname -s`.strip.downcase.to_sym
$debug_mode = ARGV.first == 'debug'

class String
  def escape
    gsub(/[^\w]/, '_')

  unless method_defined? :start_with?
    def start_with?(str)
      self[0...str.size] == str

  unless method_defined? :lines
    def lines

class Graph
  def initialize(name, protocol, parse_expr)
    @name = name
    @protocol = protocol
    @parse_expr = parse_expr

  def config
    config_options = []

    # first, build a list of multigraphs (one graph per unit)
    # Hash key is unit, and the value is array of labels
    multigraphs = {}
    @parse_expr.each do |_expr, descr|
      next unless descr # no label - skip this entry

      descr.each do |entry|
        labels_array = (multigraphs[entry[0]] ||= [])
        labels_array.push [entry[1], entry[2]]

    multigraphs.each_pair do |unit, labels_and_negatives|
      # now just add options to the config

      config_options.concat [
        "multigraph #{name(unit)}",
        "graph_title Netstat: #{@protocol}: #{@name}#{" (#{unit})" if multigraphs.size > 1}",
        'graph_category network',
        "graph_order #{ { |label, _negative| label.escape }.join(' ')}"

      config_options.push 'graph_args --base 1024' if unit == :bytes
      has_negatives = false

      labels_and_negatives.each do |label, negative|
        label_esc = label.escape
        has_negatives = true unless negative.nil?

        if negative == true
          # the value has no opposite and is negative
          config_options.concat [
            "#{label_esc}.graph no",
            "#{label_esc}_neg.type DERIVE",
            "#{label_esc}_neg.min 0",
            "#{label_esc}_neg.draw LINE",
            "#{label_esc}_neg.label #{label}",
            "#{label_esc}_neg.negative #{label_esc}"
          config_options.concat [
            "#{label_esc}.type DERIVE",
            "#{label_esc}.min 0",
            "#{label_esc}.draw LINE",
            "#{label_esc}.label #{label}"

        if negative == false
          # the value has no opposite and is positive
          config_options.concat [
            "#{label_esc}_neg.graph off",
            "#{label_esc}.negative #{label_esc}_neg"
        elsif negative
          negative_esc = negative.escape
          config_options.concat [
            "#{label_esc}.negative #{negative_esc}",
            "#{negative_esc}.graph no"

      config_options.push "graph_vlabel per second#{' in (-) / out (+)' if has_negatives}"


  def fetch(data)
    output_data = []

    # first build a set of multigraphs, one per unit.
    # Hash key is unit, and the value is a hash of 'escaped label' => 'value'
    multigraphs = {}
    @parse_expr.each do |expr, descr|
      next unless descr # no label - skip this entry

      index = data.index { |line| line =~ expr }
      if index
        data.delete_at index
        $~[1..-1].zip(descr).each do |value, info|
          unit, label = info
          (multigraphs[unit] ||= {})[label.escape] = value
        warn "no line found for #{expr}, #{descr}" if $debug_mode

    multigraphs.each_pair do |unit, values|
      output_data.push "multigraph #{name(unit)}"
      output_data += { |label, value| "#{label}.value #{value}" }


  def name(unit)

def graphs_for(protocol)
  case protocol
  # Order of the graps in each section is important for parsing.
  # At the same time, it is not important for munin, so we are OK placing it in parsing order here.
  when 'tcp'
    if $os == :linux
      ['sent', protocol, [
                    # Description of the elements of arrays below:
                    # 0: regexp to parse the line
                    # 1: Array<Array[3]> for each matching group in the regular expression.
                    #    0: unit name
                    #    1: label
                    #    2 (optional): negative label
                    #    It could be reasonable to add more elements as warning and critical values.

                    [/(\d+) segments send out$/, [[:segments, 'total']]],
                    [/(\d+) segments retransmitted$/, [[:segments, 'retransmitted']]]
                  ]),'received', protocol, [
                    [/(\d+) segments received$/, [[:segments, 'total']]],
                    [/(\d+) bad segments received.$/, [[:segments, 'bad']]]
                  ]),'connections', protocol, [
                    [/(\d+) active connections openings$/, [[:connections, 'active openings']]],
                    [/(\d+) passive connection openings$/, [[:connections, 'passive openings']]],
                    [/(\d+) failed connection attempts$/, [[:connections, 'failed attempts']]],
                    [/(\d+) connection resets received$/, [[:connections, 'RST received']]],
                    [/(\d+) connections established$/, [[:connections, 'established']]],
                    [/(\d+) resets sent$/, [[:connections, 'RST sent']]]
                  ]),'timeouts', protocol, [
                    [/(\d+) timeouts after SACK recovery$/, [[:segments, 'after SACK recovery']]],
                    [/(\d+) other TCP timeouts$/, [[:segments, 'other TCP']]],
                    [/(\d+) timeouts in loss state$/, [[:segments, 'in a loss state']]]
      ['sent', protocol, [
                    [/(\d+) packets sent$/, [[:packets, 'total']]],
                    [/(\d+) data packets \((\d+) bytes\)$/, [[:packets, 'data'], [:bytes, 'data']]],
                    [/(\d+) data packets \((\d+) bytes\) retransmitted$/, [[:packets, 'retransmitted'], [:bytes, 'retransmitted']]],
                    [/(\d+) data packets unnecessarily retransmitted$/, [[:packets, 'unnecessarily retransmitted']]],
                    [/(\d+) resends initiated by MTU discovery$/, [[:packets, 'resends initiated by MTU discovery']]],
                    [/(\d+) ack-only packets \((\d+) delayed\)$/, [[:packets, 'ack-only'], [:packets, 'ack-only delayed']]],
                    [/(\d+) URG only packets$/, [[:packets, 'URG only']]],
                    [/(\d+) window probe packets$/, [[:packets, 'window probe']]],
                    [/(\d+) window update packets$/, [[:packets, 'window update']]],
                    [/(\d+) control packets$/, [[:packets, 'control']]]
                  ]),'received', protocol, [
                    [/(\d+) packets received$/, [[:packets, 'total']]],
                    [/(\d+) acks \(for (\d+) bytes\)$/, [[:packets, 'acks'], [:bytes, 'acks']]],
                    [/(\d+) duplicate acks$/, [[:packets, 'duplicate acks']]],
                    [/(\d+) acks for unsent data$/, [[:packets, 'acks for unsent data']]],
                    [/(\d+) packets \((\d+) bytes\) received in-sequence$/, [[:packets, 'in-sequence'], [:bytes, 'in-sequence']]],
                    [/(\d+) completely duplicate packets \((\d+) bytes\)$/, [[:packets, 'completely duplicate'], [:bytes, 'completely duplicate']]],
                    [/(\d+) old duplicate packets$/, [[:packets, 'old duplicate']]],
                    [/(\d+) packets with some dup\. data \((\d+) bytes duped\)$/, [[:packets, 'some dup. data'], [:bytes, 'partial dups']]],
                    [/(\d+) out-of-order packets \((\d+) bytes\)$/, [[:packets, 'out-of-order'], [:bytes, 'out-of-order']]],
                    [/(\d+) packets \((\d+) bytes\) of data after window$/, [[:packets, 'data after window'], [:bytes, 'data after window']]],
                    [/(\d+) window probes$/, [[:packets, 'window probes']]],
                    [/(\d+) window update packets$/, [[:packets, 'window update']]],
                    [/(\d+) packets received after close$/, [[:packets, 'after close']]],
                    [/(\d+) discarded for bad checksums$/, [[:packets, 'bad checksums']]],
                    [/(\d+) discarded for bad header offset fields?$/, [[:packets, 'bad header offset flds']]],
                    [/(\d+) discarded because packet too short$/, [[:packets, 'too short']]],
                    [/(\d+) discarded due to memory problems$/, [[:packets, 'discarded: memory problems']]],
                    [/(\d+) ignored RSTs in the windows$/, [[:packets, 'ignored RSTs in windows']]],
                    [/(\d+) segments updated rtt \(of (\d+) attempts\)$/, [[:packets, 'RTT: updated'], [:packets, 'RTT: attempts to update']]]
                  ]),'connections', protocol, [
                    [/(\d+) connection requests$/, [[:connections, 'requests']]],
                    [/(\d+) connection accepts$/, [[:connections, 'accepts']]],
                    [/(\d+) bad connection attempts$/, [[:connections, 'bad attempts']]],
                    [/(\d+) listen queue overflows$/, [[:connections, 'listen queue overflows']]],
                    [/(\d+) connections established \(including accepts\)$/, [[:connections, 'established']]],
                    [/(\d+) connections closed \(including (\d+) drops\)$/, [[:connections, 'closed'], [:connections, 'dropped']]],
                    [/(\d+) connections updated cached RTT on close$/, [[:connections, 'closed & upd cached RTT']]],
                    [/(\d+) connections updated cached RTT variance on close$/, [[:connections, 'closed & upd cached RTT variance']]],
                    [/(\d+) connections updated cached ssthresh on close$/, [[:connections, 'closed & upd cached ssthresh']]],
                    [/(\d+) embryonic connections dropped$/, [[:connections, 'embryonic dropped']]]
                  ]),'timeouts', protocol, [
                    [/(\d+) retransmit timeouts$/, [[:connections, 'retransmit']]],
                    [/(\d+) connections dropped by rexmit timeout$/, [[:connections, 'retransmit: dropped']]],
                    [/(\d+) persist timeouts$/, [[:connections, 'persist']]],
                    [/(\d+) connections dropped by persist timeout$/, [[:connections, 'persist: dropped']]],
                    [/(\d+) Connections \(fin_wait_2\) dropped because of timeout$/, [[:connections, 'fin_wait_2: dropped']]],
                    [/(\d+) keepalive timeouts$/, [[:connections, 'keepalive']]],
                    [/(\d+) keepalive probes sent$/, [[:connections, 'keepalive: probes sent']]],
                    [/(\d+) connections dropped by keepalive$/, [[:connections, 'keepalive: dropped']]]
                  ]),'correct predictions', protocol, [
                    [/(\d+) correct ACK header predictions$/, [[:predictions, 'ACK header']]],
                    [/(\d+) correct data packet header predictions$/, [[:predictions, 'data packet header']]]
                  ]),'SYN', protocol, [
                    [/(\d+) syncache entries added$/, [[:entries, 'cache added']]],
                    [/(\d+) cookies sent$/, [[:entries, 'cookies sent']]],
                    [/(\d+) cookies received$/, [[:entries, 'cookies received']]],
                    [/(\d+) retransmitted$/, [[:entries, 'retransmitted']]],
                    [/(\d+) dupsyn$/, [[:entries, 'duplicates']]],
                    [/(\d+) dropped$/, [[:entries, 'dropped']]],
                    [/(\d+) completed$/, [[:entries, 'completed']]],
                    [/(\d+) bucket overflow$/, [[:entries, 'bucket overflow']]],
                    [/(\d+) cache overflow$/, [[:entries, 'cache overflow']]],
                    [/(\d+) reset$/, [[:entries, 'reset']]],
                    [/(\d+) stale$/, [[:entries, 'stale']]],
                    [/(\d+) aborted$/, [[:entries, 'aborted']]],
                    [/(\d+) badack$/, [[:entries, 'bad ACK']]],
                    [/(\d+) unreach$/, [[:entries, 'unreachable']]],
                    [/(\d+) zone failures$/, [[:entries, 'zone failures']]],
                    [/(\d+) hostcache entries added$/, [[:entries, 'hostcache added']]],
                    [/(\d+) bucket overflow$/, [[:entries, 'hostcache overflow']]]
                  ]),'SACK', protocol, [
                    [/(\d+) SACK recovery episodes$/, [[:packets, 'recovery episodes']]],
                    [/(\d+) segment rexmits in SACK recovery episodes$/, [[:packets, 'segment rexmits']]],
                    [/(\d+) byte rexmits in SACK recovery episodes$/, [[:bytes, 'bytes rexmitted']]],
                    [/(\d+) SACK options \(SACK blocks\) received$/, [[:packets, 'options blocks rcvd']]],
                    [/(\d+) SACK options \(SACK blocks\) sent$/, [[:packets, 'options blocks sent']]],
                    [/(\d+) SACK scoreboard overflow$/, [[:packets, 'scoreboard overflow']]]
                  ]),'ECN', protocol, [
                    [/(\d+) packets with ECN CE bit set$/, [[:packets, 'CE bit']]],
                    [/(\d+) packets with ECN ECT\(0\) bit set$/, [[:packets, 'ECT(0) bit']]],
                    [/(\d+) packets with ECN ECT\(1\) bit set$/, [[:packets, 'ECT(1) bit']]],
                    [/(\d+) successful ECN handshakes$/, [[:packets, 'successful handshakes']]],
                    [/(\d+) times ECN reduced the congestion window$/, [[:packets, 'congestion window reduced']]]
  when 'udp'
    if $os == :linux
      ['received', protocol, [
                    [/(\d+) datagrams received$/, [[:packets, 'total']]],
                    [/(\d+) with incomplete header$/, [[:packets, 'incomplete header']]],
                    [/(\d+) with bad data length field$/, [[:packets, 'bad data length field']]],
                    [/(\d+) with bad checksum$/, [[:packets, 'bad checksum']]],
                    [/(\d+) with no checksum$/, [[:packets, 'no checksum']]],
                    [/(\d+) dropped due to no socket$/, [[:packets, 'dropped: no socket']]],
                    [%r{(\d+) broadcast/multicast datagrams undelivered$}, [[:packets, '*cast undelivered']]],
                    [/(\d+) dropped due to full socket buffers$/, [[:packets, 'dropped: no buffers']]],
                    [/(\d+) not for hashed pcb$/, [[:packets, 'not for hashed pcb']]],
                    [/(\d+) delivered$/, [[:packets, 'delivered']]]
                  ]),'sent', protocol, [
                    [/(\d+) datagrams output$/, [[:packets, 'total']]],
                    [/(\d+) times multicast source filter matched$/, [[:packets, 'multicast src filter match']]]
  when 'ip'
    if $os == :linux
      ['received', protocol, [
                    [/(\d+) total packets received$/, [[:packets, 'total']]],
                    [/(\d+) bad header checksums$/, [[:packets, 'bad header checksum']]],
                    [/(\d+) with size smaller than minimum$/, [[:packets, 'size smaller than min']]],
                    [/(\d+) with data size < data length$/, [[:packets, 'data size < data length']]],
                    [/(\d+) with ip length > max ip packet size$/, [[:packets, 'ip length > max ip packet sz']]],
                    [/(\d+) with header length < data size$/, [[:packets, 'header length < data size']]],
                    [/(\d+) with data length < header length$/, [[:packets, 'data length < header length']]],
                    [/(\d+) with bad options$/, [[:packets, 'bad options']]],
                    [/(\d+) with incorrect version number$/, [[:packets, 'incorrect version']]],
                    [/(\d+) fragments? received$/, [[:packets, 'fragments']]],
                    [/(\d+) fragments? dropped \(dup or out of space\)$/, [[:packets, 'frags dropped: dup/out of spc']]],
                    [/(\d+) fragments? dropped after timeout$/, [[:packets, 'frags dropped: timeout']]],
                    [/(\d+) packets? reassembled ok$/, [[:packets, 'reassembled ok']]],
                    [/(\d+) packets? for this host$/, [[:packets, 'for this host']]],
                    [%r{(\d+) packets? for unknown/unsupported protocol$}, [[:packets, 'for unknown/unsup protocol']]],
                    [/(\d+) packets? forwarded \((\d+) packets fast forwarded\)$/, [[:packets, 'forwarded'], [:packets, 'fast forwarded']]],
                    [/(\d+) packets? not forwardable$/, [[:packets, 'not forwardable']]],
                    [/(\d+) packets? received for unknown multicast group$/, [[:packets, 'unknown multicast grp']]]
                  ]),'sent', protocol, [
                    [/(\d+) packets? sent from this host$/, [[:packets, 'total']]],
                    [/(\d+) redirects? sent$/, [[:packets, 'redirect']]],
                    [/(\d+) packets? sent with fabricated ip header$/, [[:packets, 'fabricated IP head']]],
                    [/(\d+) output packets? dropped due to no bufs, etc\.$/, [[:packets, 'dropped: no bufs, etc']]],
                    [/(\d+) output packets? discarded due to no route$/, [[:packets, 'discarded: no route']]],
                    [/(\d+) output datagrams? fragmented$/, [[:packets, 'fragmented']]],
                    [/(\d+) fragments? created$/, [[:packets, 'fragments created']]],
                    [/(\d+) datagrams? that can't be fragmented$/, [[:packets, "can't be fragmented"]]],
                    [/(\d+) tunneling packets? that can't find gif$/, [[:packets, 'tunneling, gif not found']]],
                    [/(\d+) datagrams? with bad address in header$/, [[:packets, 'bad address in header']]]
  when 'arp'
    if $os == :linux
      ['packets', protocol, [
                    # This is just a total, so ignore the value but keep regexp to avoid 'not parsed' warning.
                    [/(\d+) ARP packets? received$/],
                    [/(\d+) ARP requests? received$/, [[:packets, 'requests received']]],
                    [/(\d+) ARP repl(?:y|ies) received$/, [[:packets, 'replies received']]],
                    [/(\d+) ARP requests? sent$/, [[:packets, 'requests', 'requests received']]],
                    [/(\d+) ARP repl(?:y|ies) sent$/, [[:packets, 'replies', 'replies received']]],
                    [/(\d+) total packets? dropped due to no ARP entry$/, [[:packets, 'no entry']]]
                  ]),'entries', protocol, [
                    [/(\d+) ARP entrys? timed out$/, [[:entries, 'timed out']]],
                    [/(\d+) Duplicate IPs seen$/, [[:entries, 'duplicate IPs seen']]]

proto_name = File.basename($0, '.*').escape
proto_name.slice! 0, PLUGIN_NAME.size if proto_name.start_with? PLUGIN_NAME

proto_name = 'tcp' if proto_name.empty?

def netstat_s(protocol)
  if $os == :linux
    if %w[tcp udp].include?(protocol)
      `netstat -s --#{protocol}`
      `netstat -s --raw`
    `netstat -sp #{protocol}`
  end.lines.reject { |line| line =~ /^\w+:/ }

case ARGV.first
when 'autoconf'
  puts %i[linux freebsd].include?($os) ? 'yes' : 'no'
when 'suggest'
  puts $os == :linux ? %w[tcp] : %w[tcp udp ip arp]
when 'config'
  graphs_for(proto_name).each do |graph|
    puts graph.config.join $/
  data = netstat_s(proto_name)
  graphs_for(proto_name).each do |graph|
    puts graph.fetch(data).join $/

  if $debug_mode
    warn "not parsed:\n#{data.join}" unless data.empty?

# awful performance when scrolling through those regexps above
# vim: syntax=none