linux netstat - status状态描述

【基本介绍】
这里介绍netstat命令返回的结果status列的状态说明。

【状态介绍】

[root@sparkVM script]# netstat -tunlp | head -10
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address               Foreign Address             State       PID/Program name   
tcp        0      0 0.0.0.0:22                  0.0.0.0:*                   LISTEN      1842/sshd           
tcp        0      0 127.0.0.1:631               0.0.0.0:*                   LISTEN      1727/cupsd          
tcp        0      0 127.0.0.1:25                0.0.0.0:*                   LISTEN      2180/master         

   State
       The state of the socket. Since there are no states in raw mode and usually no states used in UDP, this column may be left blank.  Nor-mally this can be one of several values:

       ESTABLISHED(已创建连接，传输数据中)
              The socket has an established connection.

       SYN_SENT（尝试创建连接）
              The socket is actively attempting to establish a connection.

       SYN_RECV（接收到请求，等待确认）
              A connection request has been received from the network.

       FIN_WAIT1（socket连接关闭）
              The socket is closed, and the connection is shutting down.

       FIN_WAIT2(socket连接关闭，等待远端关闭)
              Connection is closed, and the socket is waiting for a shutdown from the remote end.

       TIME_WAIT（等待处理的请求）
              The socket is waiting after close to handle packets still in the network.

       CLOSED The socket is not being used.（无连接）

       CLOSE_WAIT（远端关闭等待socket关闭）
              The remote end has shut down, waiting for the socket to close.

       LAST_ACK（远端关闭，等待反馈）
              The remote end has shut down, and the socket is closed. Waiting for acknowledgement.
                 
       LISTEN (服务器等待进入)
             The socket is listening for incoming connections.  Such sockets are not included in the output unless you specify the --listen-ing (-l) or --all (-a) option.

       CLOSING（两边关闭）
              Both sockets are shut down but we still don’t have all our data sent.

       UNKNOWN（未知状态）
              The state of the socket is unknown.