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 -l3、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 :110014、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