如果你的日常搬砖工作不是与底层协议栈紧密相关， 知道这些也没有什么用，并且很快就会忘记，其中任何一个分支领域都不容易，关联的知识也会非常多。

连接

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连接的洪水攻击

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断开

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TCP/IP状态图详解

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TCP socket 状态表

State Endpoint Description
LISTEN Server Waiting for a connection request from any remote TCP end-point.
SYN-SENT Client Waiting for a matching connection request after having sent a connection request.
SYN-RECEIVED Server Waiting for a confirming connection request acknowledgment after having both received and sent a connection request.
ESTABLISHED Server and client An open connection, data received can be delivered to the user. The normal state for the data transfer phase of the connection.
FIN-WAIT-1 Server and client Waiting for a connection termination request from the remote TCP, or an acknowledgment of the connection termination request previously sent.
FIN-WAIT-2 Server and client Waiting for a connection termination request from the remote TCP.
CLOSE-WAIT Server and client Waiting for a connection termination request from the local user.
CLOSING Server and client Waiting for a connection termination request acknowledgment from the remote TCP.
LAST-ACK Server and client Waiting for an acknowledgment of the connection termination request previously sent to the remote TCP (which includes an acknowledgment of its connection termination request).
TIME-WAIT Server or client Waiting for enough time to pass to be sure the remote TCP received the acknowledgment of its connection termination request.[e]
CLOSED Server and client No connection state at all.

Linux查看连接状态

  1. [java@node101 ~]$ netstat -anp
  2. (Not all processes could be identified, non-owned process info
  3.  will not be shown, you would have to be root to see it all.)
  4. Active Internet connections (servers and established)
  5. Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name    
  6. tcp        0      0 0.0.0.0:111             0.0.0.0:*               LISTEN      -                   
  7. tcp        0      0 192.168.122.1:53        0.0.0.0:*               LISTEN      -                   
  8. tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      -                   
  9. tcp        0      0 127.0.0.1:631           0.0.0.0:*               LISTEN      -                   
  10. tcp6       0      0 :::111                  :::*                    LISTEN      -                   
  11. tcp6       0      0 :::22                   :::*                    LISTEN      -                   
  12. tcp6       0      0 ::1:631                 :::*                    LISTEN      -                   
  13. udp        0      0 0.0.0.0:111             0.0.0.0:*                           -                   
  14. udp        0      0 0.0.0.0:5353            0.0.0.0:*                           -                   
  15. udp        0      0 0.0.0.0:37142           0.0.0.0:*                           -                   
  16. udp        0      0 192.168.122.1:53        0.0.0.0:*                           -                   
  17. udp        0      0 0.0.0.0:67              0.0.0.0:*                           -                   
  18. udp6       0      0 :::111                  :::*                                -                   
  19. udp6       0      0 :::5353                 :::*                                -                   
  20. udp6       0      0 :::43914                :::*                                -                   
  21. Active UNIX domain sockets (servers and established)
  22. Proto RefCnt Flags       Type       State         I-Node   PID/Program name     Path
  23. unix  2      [ ACC ]     STREAM     LISTENING     19622    -                    /run/rpcbind.sock
  24. unix  2      [ ACC ]     STREAM     LISTENING     41131    1999/gnome-session-  @/tmp/.ICE-unix/1999
  25. unix  2      [ ACC ]     STREAM     LISTENING     20718    -                    @/org/kernel/linux/storage/multipathd
  26. unix  2      [ ACC ]     STREAM     LISTENING     42515    2134/ibus-daemon     @/tmp/dbus-Dhv0BQv6
  27. unix  2      [ ACC ]     STREAM     LISTENING     26396    -                    /var/run/vmware/guestServicePipe
  28. unix  2      [ ACC ]     STREAM     LISTENING     25367    -                    @irqbalance789.sock
  29. unix  2      [ ACC ]     STREAM     LISTENING     29726    -                    /run/gssproxy.sock
  30. unix  2      [ ACC ]     STREAM     LISTENING     41223    2106/Xwayland        @/tmp/.X11-unix/X0
  31. unix  2      [ ACC ]     STREAM     LISTENING     42033    -                    /run/user/1001/keyring/ssh
  32. unix  2      [ ACC ]     STREAM     LISTENING     25434    -                    /var/lib/sss/pipes/private/sbus-monitor
  33. unix  2      [ ACC ]     STREAM     LISTENING     26993    -                    /var/lib/sss/pipes/private/sbus-dp_implicit_files.834

什么是IP分片

IP数据途径较小传输负载网络时的不断分片示意图

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参考资料