带有 FIN 标志的 TCP 数据包也可以有数据吗? [英] Can a TCP packet with the FIN flag also have data?

问题描述

我正在开发一个数据包捕获程序.TCP数据包是否有可能设置了FIN标志但也有数据?

I'm working on a packet capture program. Is it possible for TCP packet to have the FIN flag set but also have data?

推荐答案

严格来说，可以将数据放入 TCP FIN 包中...引用自 RFC 793(强调我的):

Strictly speaking, it is possible to put data in a TCP FIN packet... Quoting from RFC 793 (emphasis mine):

SYN 和 FIN是唯一需要这种保护的控件，而这些控件仅在连接打开和关闭时使用.对于序列号目的，SYN 被认为发生在第一个实际数据之前它出现的段的八位字节，同时考虑 FIN在它所在的段中的最后一个实际数据八位字节之后发生发生.

The SYN and FIN are the only controls requiring this protection, and these controls are used only at connection opening and closing. For sequence number purposes, the SYN is considered to occur before the first actual data octet of the segment in which it occurs, while the FIN is considered to occur after the last actual data octet in a segment in which it occurs.

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