TCP - 是否可以将相同的客户端端口同时用于不同应用程序的不同连接? [英] TCP - possible for same client-side port to be used for different connections by different applications simlutaneously?

问题描述

在 TCP 中，不共享相同可执行映像的不同进程是否有可能(例如，没有 fork())在 Windows、Linux 或 OSX 上使用相同的客户端端口?我相信这与使用 setsockopt() 设置的套接字选项 SO_REUSEADDR 和 SO_REUSEPORT 特别相关.

Is it possible in TCP for different processes not sharing the same executable image (so no fork() for example) to use a same client-side port on Windows, Linux or OSX? This is specifically related to the socket options SO_REUSEADDR and SO_REUSEPORT set using setsockopt() I believe.

据我所知，我相信同一个进程/映像可以执行此操作，但我还没有找到有关多个进程/映像的信息.我想这在理论上是可能的，因为每个套接字都是由 5 值元组 [IP_PROTO, src_ip:src_port, dst_ip:dst_port] 定义的.所以我会假设，只要共享一个客户端端口的多个 TCP 连接没有建立到同一个 dst_ip:dst_port，这在理论上是可能的.

As far as I've read, I believe it is possible for the same process/image to do this, but I haven't found information as to multiple processes/images. I would imagine it is theoretically possible since each socket is defined by the 5-valued tuple [IP_PROTO, src_ip:src_port, dst_ip:dst_port]. So I would assume that, as long as multiple TCP connections sharing a client-side port are not made to the same dst_ip:dst_port, this would be theoretically possible.

推荐答案

UDP 不是面向连接的，客户端和服务器之间没有真正的区别，所以对于 UDP 这个问题没有多大意义.

UDP is not connection-oriented and has no real distinction between client and server, so for UDP this question doesn't make a lot of sense.

对于 TCP，您可以使用 SO_REUSEADDR 将多个客户端绑定到同一个端口，但为什么要这样做?通常，您在建立连接之前让客户端处于未绑定状态，让内核为您选择一个未使用的端口.

For TCP, you can use SO_REUSEADDR to bind mulitple clients to the same port, but why would you want to? Normally you leave the client unbound before making a connection and let the kernel pick an unused port for you.

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