server.rb

require "socket"  
echo_server = TCPServer.new('localhost', 2200)  
loop do  
  Thread.start(echo_server.accept) do |client|  
    puts "#{client.peeraddr[2]}:#{client.peeraddr[1]} is connected"
    loop do
      data = client.recvfrom( 20 )[0].chomp
      if data =="exit"
        client.puts "bye!"
        puts "#{client.peeraddr[2]}:#{client.peeraddr[1]} is disconnect"
        break
      end
      puts "I only received 20 bytes '#{data}' from #{client.peeraddr[2]}:#{client.peeraddr[1]}"
      client.puts "You said: #{data}"
    end
    client.close
  end  
end