ss 命令学习

1、统计服务器并发连接数(ss性能 > netstat)
     time netstat -ant |grep EST|wc -l
     time ss -o state established | wc -l

     为什么ss比netstat快：
netstat是遍历/proc下面每个PID目录，ss直接读/proc/net下面的统计信息。所以ss执行的时候消耗资源以及消耗的时间都比netstat少很多


2、 显示本地打开的所有端口
    ss -l

3、显示每个进程具体打开的socket
    ss -pl 
   看当前机器的11001端口被谁占用了
       ss -lp src :11001

4、显示所有tcp socket
    ss -t -a 

5、显示所有的UDP Socekt    
    ss -u -a 

6、显示所有已建立的SMTP连接
    ss -o state established `( dport = :smtp or sport = :smtp )`

7、显示所有已建立的HTTP连接(包含对外提供的80，以及访问外部的80)
    ss -o state established `( dport = :http or sport = :http )`

8、显示处在FIN-WAIT-1状态的http、https连接
    ss -o state fin-wait-1 '( sport = :http or sport = :https )'

        ss常用的state状态：
        established
        syn-sent
        syn-recv
        fin-wait-1
        fin-wait-2
        time-wait
        closed
        close-wait
        last-ack
        listen
        closing
        all : All of the above states
        connected : All the states except for listen and closed
        synchronized : All the connected states except for syn-sent
        bucket : Show states, which are maintained as minisockets, i.e. time-wait and syn-recv.
        big : Opposite to bucket state.
        established
        syn-sent
        syn-recv
        fin-wait-1
        fin-wait-2
        time-wait
        closed
        close-wait
        last-ack
        listen
        closing
        all : All of the above states
        connected : All the states except for listen and closed
        synchronized : All the connected states except for syn-sent
        bucket : Show states, which are maintained as minisockets, i.e. time-wait and syn-recv.
        big : Opposite to bucket state.

9、    找出所有连接X服务器的进程
    ss -x src /tmp/.X11-unix/* 

10、列出当前socket详细信息:
    ss -s 

11、列出本地哪个进程连接到x server
    ss -x src /tmp/ X11-unix/*

12、列出来至120.33.31.1,80端口的连接
    ss src 120.33.31.1:http
    ss src 120.33.31.1:80