Netstat 命令用于显示各种网络相关信息,如网络连接,路由表,接口状态 (Interface Statistics),masquerade 连接,多播成员 (Multicast Memberships) 等等。
[root@localhost ~]# netstat
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 52 192.168.220.129:ssh 192.168.220.1:11774 ESTABLISHED
Active UNIX domain sockets (w/o servers)
Proto RefCnt Flags Type State I-Node Path
unix 2 [ ] DGRAM 7580 /run/systemd/notify
unix 5 [ ] DGRAM 7591 /run/systemd/journal/socket
unix 26 [ ] DGRAM 7593 /dev/log
从命令的执行结果上看,netstat分为了两部分:
一个是Active Internet connections,称为有源TCP连接,其中"Recv-Q"和"Send-Q"指%0A的是接收队列和发送队列。这些数字一般都应该是0。如果不是则表示软件包正在队列中堆积。
另一个是Active UNIX domain sockets,称为有源Unix域套接口(和网络套接字一样,但是只能用于本机通信,性能可以提高一倍)。
Proto:连接使用的协议,RefCnt:连接到本套接口上的进程号,Types:套接口的类型,State:套接口当前的状态,Path:连接到套接口的其它进程使用的路径名。
常用参数
-a (all)显示所有选项,默认不显示LISTEN相关
-t (tcp)仅显示tcp相关选项
-u (udp)仅显示udp相关选项
-n 拒绝显示别名,能显示数字的全部转化成数字。
-l 仅列出有在 Listen (监听) 的服務状态
-p 显示建立相关链接的程序名
-r 显示路由信息,路由表
-e 显示扩展信息,例如uid等
-s 按各个协议进行统计
-c 每隔一个固定时间,执行该netstat命令。
提示:LISTEN和LISTENING的状态只有用-a或者-l才能看到
常用参数组合:
1.列出所有端口
[root@localhost ~]# netstat -a
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 192.168.122.1:domain 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:ssh 0.0.0.0:* LISTEN
tcp 0 0 localhost:ipp 0.0.0.0:* LISTEN
tcp 0 0 localhost:smtp 0.0.0.0:* LISTEN
tcp 0 0 localhos:x11-ssh-offset 0.0.0.0:* LISTEN
tcp 0 52 192.168.220.129:ssh 192.168.220.1:11774 ESTABLISHED
tcp6 0 0 [::]:ssh [::]:* LISTEN
tcp6 0 0 localhost:ipp [::]:* LISTEN
tcp6 0 0 localhost:smtp [::]:* LISTEN
tcp6 0 0 localhos:x11-ssh-offset [::]:* LISTEN
udp 0 0 192.168.122.1:domain 0.0.0.0:*
udp 0 0 0.0.0.0:bootps 0.0.0.0:*
udp 0 0 0.0.0.0:bootpc 0.0.0.0:*
udp 0 0 0.0.0.0:bootpc 0.0.0.0:*
udp 0 0 0.0.0.0:mdns 0.0.0.0:*
udp 0 0 0.0.0.0:55575 0.0.0.0:*
udp 0 0 0.0.0.0:13621 0.0.0.0:*
udp 0 0 0.0.0.0:48475 0.0.0.0:*
udp6 0 0 [::]:10347 [::]:*
udp6 0 0 [::]:13776 [::]:*
(-at 列出所有tcp端口,-au列出所有udp端口)
2.列出LISTEN端口
[root@localhost ~]# netstat -l
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 192.168.122.1:domain 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:ssh 0.0.0.0:* LISTEN
tcp 0 0 localhost:ipp 0.0.0.0:* LISTEN
tcp 0 0 localhost:smtp 0.0.0.0:* LISTEN
tcp 0 0 localhos:x11-ssh-offset 0.0.0.0:* LISTEN
tcp6 0 0 [::]:ssh [::]:* LISTEN
tcp6 0 0 localhost:ipp [::]:* LISTEN
tcp6 0 0 localhost:smtp [::]:* LISTEN
tcp6 0 0 localhos:x11-ssh-offset [::]:* LISTEN
udp 0 0 192.168.122.1:domain 0.0.0.0:*
udp 0 0 0.0.0.0:bootps 0.0.0.0:*
udp 0 0 0.0.0.0:bootpc 0.0.0.0:*
udp 0 0 0.0.0.0:bootpc 0.0.0.0:*
udp 0 0 0.0.0.0:mdns 0.0.0.0:*
udp 0 0 0.0.0.0:55575 0.0.0.0:*
udp 0 0 0.0.0.0:13621 0.0.0.0:*
udp 0 0 0.0.0.0:48475 0.0.0.0:*
udp6 0 0 [::]:10347 [::]:*
udp6 0 0 [::]:13776 [::]:*
(-lt 列出所有tcp的监听端口,-lu 列出所有udp的监听端口)
3.列出协议的统计信息
[root@localhost ~]# netstat -s
Ip:
1878 total packets received
0 forwarded
0 incoming packets discarded
1696 incoming packets delivered
1351 requests sent out
65 dropped because of missing route
Icmp:
0 ICMP messages received
0 input ICMP message failed.
ICMP input histogram:
16 ICMP messages sent
0 ICMP messages failed
ICMP output histogram:
destination unreachable: 16
...
4.显示PID和进程名称
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 192.168.220.129:ssh 192.168.220.1:11774 ESTABLISHED 3737/sshd: root@pts
5.显示不支持的地址组
netstat: no support for `AF IPX' on this system.
netstat: no support for `AF AX25' on this system.
netstat: no support for `AF X25' on this system.
netstat: no support for `AF NETROM' on this system.
例:输出访问tcp 22端口的客户机的ip和其访问的次数,并且输出前十
第一步通过netstat -ant查看当前tcp信息
[root@localhost ~]# netstat -ant
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 192.168.122.1:53 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:631 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:25 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:6010 0.0.0.0:* LISTEN
tcp 0 52 192.168.220.129:22 192.168.220.1:11774 ESTABLISHED
tcp6 0 0 :::22 :::* LISTEN
tcp6 0 0 ::1:631 :::* LISTEN
tcp6 0 0 ::1:25 :::* LISTEN
tcp6 0 0 ::1:6010 :::* LISTEN
第二步过滤出访问tcp 22端口的客户机ip
[root@localhost ~]# netstat -ant | awk '$1=="tcp"&&/:22/{print $5}'
0.0.0.0:*
192.168.220.1:11774
第三步过滤出输出结果的ip地址
[root@localhost ~]# netstat -ant | awk '$1=="tcp"&&/:22/{split($5,clients,":");print clients[1]}'
0.0.0.0
192.168.220.1
第四步进行统计
[root@localhost ~]# netstat -ant | awk '$1=="tcp"&&/:22/{split($5,clients,":");IPS[clients[1]]++}END{for(i in IPS)print i,IPS[i]}'
0.0.0.0 1
192.168.220.1 1
最终代码:
[root@localhost ~]# netstat -ant | awk '$1=="tcp"&&/:22/{split($5,clients,":");IPS[clients[1]]++}END{for(i in IPS) print i,IPS[i]}' | sort -nr |head -n 10