1.DDOS概述
分布式拒绝服务(DDoS:Distributed Denial of Service)攻击指借助于客户/服务器技术，将多个计算机联合起来作为攻击平台，对一个或多个目标发动DDoS攻击，从而成倍地提高拒绝服务攻击的威力。
2.编写查看DDOS攻击的脚本内容
[root@ localhost ~]# vim ddos-test.sh #写入以下内容
#!/bin/bash
netstat -ntu | awk '{print $5}' | cut -d: -f4 | sort | uniq -c | sort -n
[root@ localhost ~]# chmod +x ddos-test.sh
注释：
#!/bin/bash
netstat -ntu | awk '{print $5}' | cut -d: -f1 | sort | uniq -c | sort -n
截取外网IP和端口 截取外网的IP以：为分隔符 ｜排序 ｜ 排除相同的记录 ｜ 排序并统计
注：这个脚本在不同的机器上执行时，因为 print $5 取得的结果不一样，所以需要根据实际情况，改变cut -d: -f1 中fn的值。 如果-f1 不行，就使用f4
cut -d: -f1 #以冒号为分隔符，取第一列的值。
3.模拟DDOS攻击
安装Apache
[root@ localhost ~]# yum -y install httpd
[root@ localhost ~]# systemctl start httpd
[root@ localhost ~]# ab -n 100 -c 10 http://192.168.1.63/index.html #开始攻击
[root@ localhost ~]# ./ddos-test.sh #查看已经建立的网络连接数
4.检测是否有DDOS攻击
执行：
[root@ localhost ~]# netstat -ntu | awk '{print $5}' | cut -d: -f4 | sort | uniq -c | sort -n
5.如果发现某个IP连接数据上百的链接，说明就有DDOS攻击。安装DDoS deflate
[root@ localhost ~]# wget http://www.inetbase.com/scripts/ddos/install.sh
下载DDoS deflate，保证可以上网
[root@ localhost ~]# chmod 700 install.sh #添加权限
[root@ localhost ~]# ./install.sh #执行
Installing DOS-Deflate 0.6
Downloading source files.........done
Creating cron to run script every minute.....(Default setting).....done
Installation has completed.
Config file is at /usr/local/ddos/ddos.conf
Please send in your comments and/or suggestions to [email protected]
6.修改配置文件
[root@ localhost ~]# vim /usr/local/ddos/ddos.conf
##### Paths of the script and other files
PROGDIR="/usr/local/ddos"
PROG="/usr/local/ddos/ddos.sh"
IGNORE_IP_LIST="/usr/local/ddos/ignore.ip.list"
CRON="/etc/cron.d/ddos.cron"
APF="/etc/apf/apf"
IPT="/sbin/iptables"
##### frequency in minutes for running the script
##### Caution: Every time this setting is changed, run the script with --cron
##### option so that the new frequency takes effect
FREQ=1
##### How many connections define a bad IP? Indicate that below.
NO_OF_CONNECTIONS=150
##### APF_BAN=1 (Make sure your APF version is atleast 0.96)
##### APF_BAN=0 (Uses iptables for banning ips instead of APF)
APF_BAN=1
改： APF_BAN=1
为： APF_BAN=0
##### KILL=0 (Bad IPs are'nt banned, good for interactive execution of script)
##### KILL=1 (Recommended setting)
KILL=1
##### An email is sent to the following address when an IP is banned.
##### Blank would suppress sending of mails
EMAIL_TO=[[email protected]](mailto:[email protected]) #当IP被屏蔽时给指定邮箱发送邮件报警，换成自己的邮箱即可
##### Number of seconds the banned ip should remain in blacklist.
BAN_PERIOD=600 #禁用IP时间，默认600秒，可根据情况调整
用户可根据给默认配置文件加上的注释提示内容，修改配置文件。\****
注：安装后，不需要手动运行任何软件，因为有crontab计划任务，每过一分钟，会行自动执行一次。检查是否有不正常的访问量
7.在另一台centos7上模拟安装apache，并启动DDOS
[root@ localhost ~]# yum -y install httpd
[root@ localhost ~]# systemctl start httpd
[root@ localhost ~]# ab -n 1000 -c 10 http://10.0.0.73/index.html
8.等待一分钟后，在另一台虚拟机查看结果，多了一条规则成功
返回ddos主机执行
[root@ localhost ~]# iptables -L -n
Chain INPUT (policy ACCEPT)
target prot opt source destination
DROP all -- 10.0.0.74 0.0.0.0/0
Chain FORWARD (policy ACCEPT)
target prot opt source destination
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
You have mail in /var/spool/mail/root
