code: func (p *protocol) NewRawEndpoint(stack *stack.Stack, netProto tcpip.NetworkProtocolNumber, waiterQueue *waiter.Queue) (tcpip.Endpoint, *tcpip.Error) {
  	return nil, tcpip.ErrUnknownProtocol
  }
docs: // NewRawEndpoint creates a new raw TCP endpoint. Raw TCP sockets are currently
  // unsupported. It implements stack.TransportProtocol.NewRawEndpoint.