具体的可以参考这里
他的最大特点是快, 当你的系统有上万个tcp链接要了解的时候的时候, 你就知道我说什么了. netstat等常规工具变成废铁了, 这时候他的作用就非常明显了.
/proc interface is inadequate, unfortunately. When amount of sockets is enough large, netstat or even plain cat /proc/net/tcp/ cause nothing but pains and curses. In linux-2.4 the desease became worse: even if amount of sockets is small reading /proc/net/tcp/ is slow enough.
This utility presents a new approach, which is supposed to scale well. I am not going to describe technical details here and will concentrate on description of the command. The only important thing to say is that it is not so bad idea to load module tcp_diag, which can be found in directory Modules of iproute2. If you do not make this ss will work, but it falls back to /proc and becomes slow like netstat, well, a bit faster yet (see section “Some numbers”).
从技术上讲, 它主要是通过/proc来获取各种各样的统计信息. 特别是当处理tcp的时候用到了, tcp_diag功能. tcp_diag是tcp协议栈用于诊断和统计的一个模块, 用netfilter来获取第一手的信息的. ss就用到了这个技术, 保证了信息的快捷获取.
这个软件是隶属于iproute包的, 如果你的系统没有的话可以这样安装:
1 apt-get -y install iproute
用它可以了解下协议栈占用的内存, 每个链接的队列使用情况, 每个链接属于哪个进程. 而之前唯一能用的就是:
1 watch -n 1 'cat /proc/net/sockstat'
下面简单介绍下他的使用:
01 root@ubuntu:/usr/src/iproute-20090324/misc
03ss [ OPTIONS ] [ FILTER ]
04-h, --help this message
05-V, --version output version information
06-n, --numeric don't resolve service names
07-r, --resolve resolve host names
08-a, --all display all sockets
09-l, --listening display listening sockets
10-o, --options show timer information
11-e, --extended show detailed socket information
12-m, --memory show socket memory usage
13-p, --processes show process using socket
14-i, --info show internal TCP information
15-s, --summary show socket usage summary
17-4, --ipv4 display only IP version 4 sockets
18-6, --ipv6 display only IP version 6 sockets
19-0, --packet display PACKET sockets
20-t, --tcp display only TCP sockets
21-u, --udp display only UDP sockets
22-d, --dccp display only DCCP sockets
23-w, --raw display only RAW sockets
24-x, --unix display only Unix domain sockets
25 -f, --family=FAMILY display sockets of type FAMILY
28QUERY := {all|inet|tcp|udp|raw|unix|packet|netlink}[,QUERY]
30 -F, --filter=FILE read filter information from FILE
31FILTER := [ state TCP-STATE ] [ EXPRESSION ]
01 root@ubuntu:/usr/src/iproute-20090324/misc
02Total: 750 (kernel 761)
03TCP: 21 (estab 7, closed 0, orphaned 0, synrecv 0, timewait 0/0), ports 0
05Transport Total IP IPv6
01 root@ubuntu:/usr/src/iproute-20090324/misc
02State Recv-Q Send-Q Local Address:Port Peer Address:Port
03 ESTAB 0 0 192.168.235.147:ssh 192.168.235.155:4251
05CLOSE-WAIT 38 0 192.168.235.147:13910 174.36.30.67:https
07 ESTAB 0 0 192.168.235.147:ssh 192.168.235.155:4635
09ESTAB 0 0 127.0.0.1:4369 127.0.0.1:54620
11 ESTAB 0 0 192.168.235.147:ssh 192.168.235.155:1095
13ESTAB 0 0 127.0.0.1:4369 127.0.0.1:44234
15ESTAB 0 0 127.0.0.1:54620 127.0.0.1:4369
17ESTAB 0 0 127.0.0.1:44234 127.0.0.1:4369
01 root@ubuntu:/usr/src/iproute-20090324/misc
02State Recv-Q Send-Q Local Address:Port Peer Address:Port
03 ESTAB 0 0 192.168.235.147:ssh 192.168.235.155:4251 users:(("sshd",8373,3))
04 CLOSE-WAIT 38 0 192.168.235.147:13910 174.36.30.67:https users:(("dropbox",2674,13))
05 ESTAB 0 0 192.168.235.147:ssh 192.168.235.155:4635 users:(("sshd",350,3))
06 ESTAB 0 0 127.0.0.1:4369 127.0.0.1:54620 users:(("epmd",28338,5))
07 ESTAB 0 0 192.168.235.147:ssh 192.168.235.155:1095 users:(("sshd",29044,3))
08 ESTAB 0 0 127.0.0.1:4369 127.0.0.1:44234 users:(("epmd",28338,4))
09 ESTAB 0 0 127.0.0.1:54620 127.0.0.1:4369 users:(("beam.smp",25947,11))
10 ESTAB 0 0 127.0.0.1:44234 127.0.0.1:4369 users:(("inet_gethost",23783,8),("inet_gethost",23784,8))
11 root@ubuntu:/usr/src/iproute-20090324/misc
12State Recv-Q Send-Q Local Address:Port Peer Address:Port
13 ESTAB 0 0 192.168.235.147:ssh 192.168.235.155:4251
14cubic rto:396 rtt:124.5/66 ato:40 cwnd:4 send 375.3Kbps rcv_rtt:296456 rcv_space:66472
15CLOSE-WAIT 38 0 192.168.235.147:13910 174.36.30.67:https
16cubic wscale:7,9 rto:612 rtt:256/52 ato:40 cwnd:5 send 213.8Kbps rcv_rtt:259 rcv_space:5840
17 ESTAB 0 0 192.168.235.147:ssh 192.168.235.155:4635
18cubic rto:356 rtt:144/33 ato:40 cwnd:4 send 324.4Kbps rcv_rtt:511258 rcv_space:46760
19ESTAB 0 0 127.0.0.1:4369 127.0.0.1:54620
20cubic wscale:9,9 rto:204 rtt:4/2 ato:40 cwnd:3 send 98.3Mbps rcv_space:32768
21 ESTAB 0 0 192.168.235.147:ssh 192.168.235.155:1095
22cubic rto:232 rtt:21/18 ato:40 cwnd:5 ssthresh:4 send 2.8Mbps rcv_rtt:173516 rcv_space:118904
23ESTAB 0 0 127.0.0.1:4369 127.0.0.1:44234
24cubic wscale:9,9 rto:204 rtt:4/2 ato:40 cwnd:3 send 98.3Mbps rcv_space:32768
25ESTAB 0 0 127.0.0.1:54620 127.0.0.1:4369
26cubic wscale:9,9 rto:204 rtt:4/2 ato:40 cwnd:3 send 98.3Mbps rcv_space:32792
27ESTAB 0 0 127.0.0.1:44234 127.0.0.1:4369
28cubic wscale:9,9 rto:204 rtt:4/2 ato:40 cwnd:3 send 98.3Mbps rcv_space:32792
01 root@ubuntu:/usr/src/iproute-20090324/misc
02State Recv-Q Send-Q Local Address:Port Peer Address:Port
03 ESTAB 0 0 192.168.235.147:ssh 192.168.235.155:4251 timer:(keepalive,50min,0) ino:1843366 sk:c2ea2600
04CLOSE-WAIT 38 0 192.168.235.147:13910 174.36.30.67:https ino:12200 sk:c2ea2140
05 ESTAB 0 0 192.168.235.147:ssh 192.168.235.155:4635 timer:(keepalive,2min59sec,0) ino:1101514 sk:c2ea4740
06ESTAB 0 0 127.0.0.1:4369 127.0.0.1:54620 ino:2309430 sk:c2ea2ac0
07 ESTAB 0 0 192.168.235.147:ssh 192.168.235.155:1095 timer:(keepalive,6min59sec,0) ino:379842 sk:c2f4af80
08ESTAB 0 0 127.0.0.1:4369 127.0.0.1:44234 ino:2044745 sk:c2ea3440
09ESTAB 0 0 127.0.0.1:54620 127.0.0.1:4369 ino:2309429 sk:c2ea7200
10ESTAB 0 0 127.0.0.1:44234 127.0.0.1:4369 ino:2044744 sk:c2ea1300
01 root@ubuntu:/usr/src/iproute-20090324/misc
02State Recv-Q Send-Q Local Address:Port Peer Address:Port
03 ESTAB 0 0 192.168.235.147:ssh 192.168.235.155:4251 timer:(keepalive,50min,0)
04CLOSE-WAIT 38 0 192.168.235.147:13910 174.36.30.67:https
05 ESTAB 0 0 192.168.235.147:ssh 192.168.235.155:4635 timer:(keepalive,2min50sec,0)
06ESTAB 0 0 127.0.0.1:4369 127.0.0.1:54620
07 ESTAB 0 0 192.168.235.147:ssh 192.168.235.155:1095 timer:(keepalive,6min50sec,0)
08ESTAB 0 0 127.0.0.1:4369 127.0.0.1:44234
09ESTAB 0 0 127.0.0.1:54620 127.0.0.1:4369
10ESTAB 0 0 127.0.0.1:44234 127.0.0.1:4369
Have fun!!!