upnp.rb

require 'socket'
require 'thread'

query = <<QUERY
M-SEARCH * HTTP/1.1
HOST: 239.255.255.250:1900
MAN: "ssdp:discover"
MX: 3
ST: urn:schemas-upnp-org:device:InternetGatewayDevice:1
QUERY

sock = UDPSocket.open
sock.bind("0.0.0.0",1900)

thread = Thread.new do
  loop do
    puts sock.recv(65535)
  end
end

sock.send(query, 0, "239.255.255.250", 1900)
sleep 1
thread.kill
sock.close