netstat -ntu | awk '{print $5}' | cut -d: -f1 | sort | uniq -c | sort -n 

DDos-defalte
DDOS defalte是一款免费的用来防御和减轻DDoS攻击。它通过netstat监测跟踪创建大量网络连接的IP地址，在检测到某个结点超过预设的限制时，该程序会通过APF或iptables禁止或阻挡这些IP.

#该版对原版进行了错误修复，而且进行了本地化不需要安装的时候下载文件。

#安装步骤

下载 ddos-defalte.tar.gz
tar zxfv ddos-defalte.tar.gz
cd ddos-defalte
./install.sh
安装完毕。
配置文件位于 /usr/local/ddos/ddos.conf
ip白名单文件位于 /usr/local/ddos/ignore.ip.list ，格式：一行一个ip
配置完毕之后执行命令 ddos 可以看到一行行的输出，每行：第一个是连接数 第二个是对应ip
/usr/local/sbin/ddos命令是脚本/usr/local/ddos/ddos.sh的一个软链接
安装完毕。 然后只需要计划任务周执 ddos 命令即可。ddos每执行一次都会检测配置里面的设置监测系统网络连接情况封ip。
比如root帐号下，执crontab -e 可以这样执行计划任务 */1 * * * * /usr/local/ddos/ddos.sh >/dev/null 2>&1
命令ddos有一些带参数的用法，可以通过ddos -h 了解用法。
配置文件/usr/local/ddos/ddos.conf的一些简要说明：

PROGDIR="/usr/local/ddos" 
PROG="/usr/local/ddos/ddos.sh" 
IGNORE_IP_LIST="/usr/local/ddos/ignore.ip.list"  #ip的白名单 
APF="/etc/apf/apf" 
IPT="/sbin/iptables" 

##### How many connections define a bad IP? Indicate that below. 
NO_OF_CONNECTIONS=100 #一个ip超过100个连接数,自动封掉 

##### 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=0 #这里我使用iptables封ip 

##### 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 ,设置为 root 则不发邮件
EMAIL_TO="root"  #封ip,自动发送邮件 

##### Number of seconds the banned ip should remain in blacklist. 
BAN_PERIOD=600 

import os
import time
def fyddos():
    IGNORE_IP_LIST = "/usr/local/ddos/ignore.ip.list"
    PGOPDIR="/usr/local/ddos/ddos.conf"
    PROG = "/usr/local/ddos/ddos.sh"
    if os.path.exists(PROG):
     print '[+]The execution file exists to continue the program.'
    else:
        print '[-]The execution file does not exist, the closing procedure.'
        exit()
    if os.path.exists(PGOPDIR):
        print '[+]The configuration file exists to start the execution of the program.'
    else:
        print '[-]There is no exit procedure for the configuration file.'
        exit()
    if os.path.exists(IGNORE_IP_LIST):
        print '[+]The IP white list file exists to continue the program.'
    else:
        print '[-]IP white list file does not exist, end the program.'
        exit()

    time.sleep(1)
    print '[+]Start configuring the IP white list.'
    IPlist=raw_input('Please enter your white list IP, and if not, enter q to enter the next step:')
    if IPlist=='q':
        try:
          import dy1
        except Exception , g:
            print '[-]Catch the error cause:',g
        print '[+]It has been added to it.'
        time.sleep(3)
        try:
          import dy2
        except Exception , r:
            print '[-]Catch the error cause:',r
        time.sleep(3)
        try:
            import dy3
        except Exception , p:
            print '[-]Catch the error cause:',p
        print '[+]Query information,Please input: netstat -ntu | awk ''{print $5}'' | cut -d: -f1 | sort | uniq-c | sort -n command view.'
        isd=os.system('ddos')
        sda=os.system('service iptables status')
        print isd
        print sda

    else:
        list=open('/usr/local/ddos/ignore.ip.list','w')
        list.write(IPlist+"\n")
        print '[+]It has been added to it:',IPlist
        time.sleep(3)
        try:
          import dy1
        except Exception , w:
          print('[-]Catch the error cause:',w)
        time.sleep(3)
        try:
            import dy2
        except Exception , d:
            print '[-]Catch the error cause:',d
        time.sleep(3)
        try:
            import dy3
        except Exception ,z:
            print '[-]Catch the error cause:',z
        print '[+]Query information,Please input: netstat -ntu | awk ''{print $5}'' | cut -d: -f1 | sort | uniq-c | sort -n command view.'
        isds = os.system('ddos')
        sdas= os.system('service iptables status')
        print isds
        print sdas

fyddos()

conf=input('Please enter an IP number more than how many connections will be blocked:')
data = ''
with open('/usr/local/ddos/ddos.conf', 'r+') as f:
    for line in f.readlines():
        if (line.find('NO_OF_CONNECTIONS') == 0):
            line = 'NO_OF_CONNECTIONS={}'.format(conf) + '\n'
        data += line

with open('/usr/local/ddos/ddos.conf', 'r+') as f:
    f.writelines(data)

lv=raw_input('Use APF or iptables to seal IP. It is recommended to use iptables to change the value of APF_BAN to 0:')
data=''
with open('/usr/local/ddos/ddos.conf','r+') as f:
    for line in f.readlines():
        if(line.find('APF_BAN')==0):
            line='APF_BAN={}'.format(lv)+'\n'
        data+=line

with open('/usr/local/ddos/ddos.conf','r+') as f:
    f.writelines(data)