client.rb

require 'drb'

host = "localhost"
port = 9876

uri = "druby://#{host}:#{port}"

10.times do
  local_ip = UDPSocket.open {|s| s.connect(host, 1); s.addr.last}
  DRb.start_service "druby://#{local_ip}:0"
  obj = DRbObject.new(nil, uri)
  puts "Our waiter is #{obj.name}"
  obj.thread = Thread.current
  sleep
  puts "Goodbye!"
  DRb.stop_service
end

server.rb

require 'drb'
host = "0.0.0.0"
port = 9876
uri = "druby://#{host}:#{port}"

Waiter = Struct.new(:name, :thread)

%w[John Dylan Bob Sylvia Anna].cycle do |name|
  DRb.start_service uri, w=Waiter.new(name)
  puts "#{w.name} is waiting"
  sleep 0.1 until w.thread
  puts "got client!"
  sleep 1
  w.thread.run
  DRb.stop_service
end