def start(io)
      # start SSL negotiation
      ssl = OpenSSL::SSL::SSLSocket.new(io, @ctx)
      # connect to server socket
      ssl.accept
      # make sure to close also the underlying io
      ssl.sync_close = true
      # return as new io socket
      return ssl
    end
def start(io)
      # start SSL negotiation
      ssl = OpenSSL::SSL::SSLSocket.new(io, @ctx)
      # connect to server socket
      ssl.accept
      # make sure to close also the underlying io
      ssl.sync_close = true
      # return as new io socket
      return ssl
    end
start ssl connection over existing tcpserver socket