Cisco CDPviaSNMP-to-Graphviz Creator

gistfile1.rb

#!/usr/bin/env ruby

require 'getoptlong'
require 'rubygems'
require 'snmp'

SNMP_COMMUNITY = 'public'
HOSTNAME_BLACKLIST = [ "that_one_switch_thats_down_but_in_dns" ]
ZONE_FILE = /path/to/dns/zone/file
HOSTNAME_REGEX = /^\s?(switch[0-9]+)/i

$QUICK_TEST = false

opts = GetoptLong.new( ['--quick-test', '-q', GetoptLong::NO_ARGUMENT ] )
opts.each do |opt,val|
  case opt
  when '--quick-test'
    $QUICK_TEST = true
  end
end

def snmp_get(oid, host)
  oid = SNMP::ObjectId.new(oid)
  manager = SNMP::Manager.new(:Host => host, :Community => SNMP_COMMUNITY)
  vb = manager.get(oid).varbind_list.first
  return vb.value
end

def snmp_get_tree(oid, host, index_distance_from_end)
  index_distance_from_end += 1
  oid = SNMP::ObjectId.new(oid)
  manager = SNMP::Manager.new(:Host => host, :Community => SNMP_COMMUNITY)
  results = []
  manager.walk(oid) do |varbind|
    results << [ varbind.name, varbind.value ]
  end
  results.map! do |tuple|
    [ tuple[0].to_s.split('.')[-index_distance_from_end], tuple[1] ]
  end

  result_hash = {}

  results.each do |name, value|
    result_hash[name.to_s] = value
  end

  return result_hash
end

raw_lines = open(ZONE_FILE, 'r').readlines
switch_like_records = raw_lines.select { |line| line.match(HOSTNAME_REGEX) }
switch_like_hostnames = switch_like_records.map { |record| record.match(HOSTNAME_REGEX).captures.first }

if $QUICK_TEST then
  switch_like_hostnames = switch_like_hostnames[0..10]
end

HOSTNAME_BLACKLIST.each { |b| switch_like_hostnames.delete(b) }

if_mib_ifdescr = '1.3.6.1.2.1.2.2.1.2'
cdpGlobalDeviceId = '1.3.6.1.4.1.9.9.23.1.3.4.0'
cdpInterfaceEntry = '1.3.6.1.4.1.9.9.23.1.1.1.1.6'
cdpCacheVersion = '1.3.6.1.4.1.9.9.23.1.2.1.1.5'
cdpCacheDeviceId = '1.3.6.1.4.1.9.9.23.1.2.1.1.6'
cdpCacheDevicePort = '1.3.6.1.4.1.9.9.23.1.2.1.1.7'

#inter_switch_links = {}
inter_switch_links = []

switch_like_hostnames.each do |switch|
  STDERR.puts "Scanning #{switch}..."
  cdp_host_name = snmp_get(cdpGlobalDeviceId, switch).to_s
  idb_list = snmp_get_tree(if_mib_ifdescr, switch, 0)
  cdp_neighbor_switches = snmp_get_tree(cdpCacheDeviceId, switch, 1)
  cdp_neighbor_ports = snmp_get_tree(cdpCacheDevicePort, switch, 1)
  cdp_neighbor_software = snmp_get_tree(cdpCacheVersion, switch, 1)

  links = [] # e.g. [ ["switch1", "GigabitEthernet0/1"], ["switch2", "GigabitEthernet0/1"] ]
  cdp_neighbor_switches.each do |ifindex, remote_hostname|
    local_port_name = idb_list[ifindex]
    remote_port_name = cdp_neighbor_ports[ifindex] || Unknown

    links << [ [cdp_host_name, local_port_name], [remote_hostname, remote_port_name] ]
  end

  inter_switch_links.concat(links)
end

# Remove cycles in the graph.
inter_switch_links.each do |side_a_one, side_b_one|
  inter_switch_links.reject! { |side_a_two, side_b_two| side_a_two == side_b_one }
end

# Pretty-printer.
#inter_switch_links.each do |local, remote|
#  puts "#{local[0]}:#{local[1]}  -->  #{remote[0]}:#{remote[1]}"
#end

# Generate a dot file.
graph_host_names = inter_switch_links.map{ |link| [ link[0][0], link[1][0] ] }.flatten.sort.uniq

puts "graph hosts {"
graph_host_names.each do |node|
puts "  \"#{node}\" [label=\"#{node}\"];"
end
inter_switch_links.each do |link|
puts "  \"#{link[0][0]}\" -- \"#{link[1][0]}\";"
end
puts "}"