标签归档:DDoS

Use a load-balancer as a first row of defense against DDOS

We’ve seen recently more and more DOS and DDOS attacks. Some of them were very big, requiring thousands of computers…
But in most cases, this kind of attacks are made by a few computers aiming to make a service or website unavailable, either by sending it too many requests or by taking all its available resources, preventing regular users to use the service.
Some attacks targets known vulnerabilities of widely used applications.

In the present article, we’ll explain how to take advantage of an application delivery controller to protect your website and application against DOS, DDOS and vulnerability scans.

Why using a LB for such protection since a firewall and a Web Application Firewall (aka WAF) could already do the job?
Well, the Firewall is not aware of the application layer but would be useful to pretect against SYN flood attacks. That’s why we saw recently application layer firewalls: Web Application Firewalls, also known as WAF.
Well, since the load balancer is in front of the platform, it can be a good partner for the WAF, filtering out 99% of the attacks, which are managed by script kiddies. The WAF can then happily clean up the remaining attacks.
Well, maybe you don’t need a WAF and you want to take advantage of your Aloha and save some money ;).

Note that you need an application layer load-balancer, like Aloha or OpenSource HAProxy to be efficient. 继续阅读

深入浅出DDoS攻击防御——攻击篇

1.   DDoS攻击基础

DDoS(Distributed Denial of Service,分布式拒绝服务)攻击的主要目的是让指定目标无法提供正常服务,甚至从互联网上消失,是目前最强大、最难防御的攻击之一。

按照发起的方式,DDoS可以简单分为三类。

第一类以力取胜,海量数据包从互联网的各个角落蜂拥而来,堵塞IDC入口,让各种强大的硬件防御系统、快速高效的应急流程无用武之地。这种类型的攻击典型代表是ICMP Flood和UDP Flood,现在已不常见。

第二类以巧取胜,灵动而难以察觉,每隔几分钟发一个包甚至只需要一个包,就可以让豪华配置的服务器不再响应。这类攻击主要是利用协议或者软件的漏洞发起,例如Slowloris攻击、Hash冲突攻击等,需要特定环境机缘巧合下才能出现。

第三类是上述两种的混合,轻灵浑厚兼而有之,既利用了协议、系统的缺陷,又具备了海量的流量,例如SYN Flood攻击、DNS Query Flood攻击,是当前的主流攻击方式。

本文将一一描述这些最常见、最具代表性攻击方式,并介绍它们的防御方案。 继续阅读

关于Apache (httpd)服务器防DDOS模块mod_evasive的使用说明

关于Apache (httpd)服务器防DDOS模块mod_evasive的使用说明
作者:北南南北
来自:LinuxSir.Org
摘要:在服务器管理中,经常遇到DDOS攻击WWW服务器。对于Apache(httpd)服务器来说,防御DDOS是通过mod_evasive来实现的。本文将介绍mod_evasive模块的安装、配置;
目录

1、 mod_evasive 介绍;
2、 mod_evasive 的安装和配置;
2.1  mod_evasive 的下载地址;
2.2  mod_evasive 的安装;
2.3  mod_evasive 的配置;
2.4  对mod_evasive测试验证 ;
3、mod_evasive 的高级配置;
4、关于本文;
5、参考文档;
6、相关文档; 继续阅读

DDoS攻击原理及防范

分布式拒绝服务攻击(DDoS)是目前黑客经常采用而难以防范的攻击手段。本文从概念开始详细介绍了这种攻击方式,着重描述了黑客是如何组织并发起的DDoS攻击,结合其中的Syn Flood实例,您可以对DDoS攻击有一个 更形象的了解。最后作者结合自己的经验与国内网络安全的现况探讨了一些防御DDoS的实际手段。  继续阅读