1. 限制 client 每秒访问次数
    限制連 80 port 的次數 = 60 秒 2次 , 超過就 drop
    iptables -I INPUT -p tcp –dport 80 -i eth0 -m state –state NEW -m recent –set
    iptables -I INPUT -p tcp –dport 80 -i eth0 -m state –state NEW -m recent –update –seconds 60 –hitcount 2 -j DROP

2. 控制client访问特定的port
     只允许114.80.192.18 和 127.0.0.1 访问8080-8099的端口
     iptables -A INPUT -p tcp -s 114.80.192.18 --dport 8080:8099  -j ACCEPT
     iptables -A INPUT -p tcp -s ! 127.0.0.1 --dport 8080:8099  -j DROP
    
链接:
        http://dai8700.blog.163.com/blog/static/6336012920088199455733/?hasChannelAdminPriv=true
        http://www.linuxhomenetworking.com/wiki/index.php/Quick_HOWTO_:_Ch14_:_Linux_Firewalls_Using_iptables
        http://hi.baidu.com/xuecj/blog/item/b75396018cde5bdc277fb5cb.html