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如果客户端的端口在服务器发现期间已被占用，如何更改服务器中的UDP广播端口？

[英]How to change UDP broadcast port in the server if client's port is already occupied during server discovery?

原文 2019-04-03 07:47:28 8 1 java/ android/ udp/ broadcast/ service-discovery

I am trying to implement a server discovery between a PC (server) and an android phone, broadcasting a message from the server on a common port (8888). 我正在尝试在PC（服务器）和Android手机之间实现服务器发现，在公共端口（8888）上从服务器广播消息。 I wonder what should I do if the port is already taken in the client, how can I change port on both, so that the client receives the broadcast message? 我想知道如果端口已经在客户端中，我应该怎么做，如何更改端口，以便客户端接收广播消息？ Should I use any specific network discovery protocol (UPnP or similar)? 我应该使用任何特定的网络发现协议（UPnP或类似的）吗？

Sorry if it is a basic question but I am not familiar with network programming. 对不起，如果这是一个基本问题，但我不熟悉网络编程。 I will edit my question according to your observations. 我会根据你的观察编辑我的问题。

I could only find this, but it has no answer: How to listen for a UDP broadcast when the default port could be already taken 我只能找到这个，但它没有答案：如何在已经采用默认端口时监听UDP广播

1 个解决方案

Ideally, use an existing service discovery protocol like SSDP. 理想情况下，使用现有的服务发现协议，如SSDP。 There is some prior work on this for Android you may be able to build from: https://github.com/resourcepool/ssdp-client 有一些关于Android的先前工作，您可以从以下构建： https ： //github.com/resourcepool/ssdp-client

The reasons to use SSDP: 使用SSDP的原因：

You're not going to run into any conflicts since the ports are properly reserved. 由于端口已正确保留，因此您不会遇到任何冲突。
It uses multicast rather than broadcast. 它使用多播而不是广播。 This may not matter much for you on your network, but IPv6 doesn't support broadcast, so it's already compatible. 这可能对您的网络没什么影响，但IPv6不支持广播，因此它已经兼容。
It's a standard protocol, so network administrators know what it is and can handle the traffic. 它是一种标准协议，因此网络管理员知道它是什么并且可以处理流量。