probe_ips.rb

#!/usr/bin/env ruby
 
# multithreaded script that probes a subnet for used/unused ip addresses
# command line usage:
#
# ./probe_ips.rb [options] [subnet]
#
# subnet defaults to 192.168.1
# -u lists used ips rather than unused
#
# should work on Mac, Linux, and Windows
 
class IPProber
  
  WAIT = 3 # seconds
  MAX_THREADS = 50
  
  def initialize(subnet)
    @subnet = subnet
    @available = []
    @used = []
    @threads = []
  end
  
  def probe
    (1..254).each do |index|
      ip = @subnet + index.to_s
      print ip + " \r"; $stdout.flush
      @threads << Thread.new do
        if (result = `ping -#{RUBY_PLATFORM =~ /mswin/i ? 'n' : 'c'} 1 -#{RUBY_PLATFORM =~ /darwin|mswin/i ? 'i' : 'w'} #{WAIT} #{ip}`) =~ /100% (packet )?loss/
          @available << ip
        else
          @used << ip
        end
      end
      if @threads.length >= MAX_THREADS
        @threads.shift.join
      end
    end
    @threads.each { |t| t.join }
    puts # clear line on console
  end
  
  def available
    @available.sort_by { |ip| ip.split('.').last.to_i }
  end
  
  def used
    @used.sort_by { |ip| ip.split('.').last.to_i }
  end
  
  def all
    (@available + @used).sort_by { |ip| ip.split('.').last.to_i }
  end
 
end
 
if $0 == __FILE__
  puts "probing ips..."
  used = ARGV.delete('-u') || ARGV.delete('--used')
  subnet = ARGV.first.dup rescue '192.168.1'
  subnet << '.' unless subnet =~ /\.$/
  prober = IPProber.new(subnet)
  prober.probe
  if used
    puts 'Used IPs:'
    puts prober.used
    puts "#{prober.used.length}/#{prober.all.length}"
  else
    puts 'Available IPs:'
    puts prober.available
    puts "#{prober.available.length}/#{prober.all.length}"
  end
end