【探索Linux】P.38（传输层 —— TCP协议通信连接管理机制简介 | TCP连接状态转换）

TCP协议为了管理通信连接，定义了一系列的状态转换图，这些状态转换图描绘了TCP连接从开始到结束的生命周期中所经历的各种状态。以下是TCP连接状态转换图的核心部分：

                                   +----------+
                                   |  CLOSED  |
                                   +----------+
                                      |     ^
                                      v     |
                                   +----------+
                                   |  LISTEN  |
                                   +----------+
                                      |     ^
                                      v     |
                                   +----------+
                                   |  SYN_RCVD|
                                   +----------+
                                      |     ^
                                      v     |
                 +------------------+-----------+
                 |                  |           |
                 v                  v           v
           +----------+          +----------+    +----------+
           |  SYN_SENT|          | SYN_SENT|    |  CLOSED  |
           +----------+          +----------+    +----------+
                |                    |               |     ^
                v                    v               v     |
         +---------------+          +---------------+      |
         |     ESTAB     |          |     ESTAB     |      |
         |               |          |               |      |
         |               |          |               |      |
         +---------------+          +---------------+      |
                |                    |               |      |
                v                    v               v      |
         +---------------+          +---------------+      |
         |    FIN_WAIT1  |          |    FIN_WAIT2  |      |
         +---------------+          +---------------+      |
                |                    |               |      |