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I had to install mod antiloris in order to be sure the Apache is secureagainst the slowloris Denial of Service attack that emerged in the summer of 2008.
Luckily David Hrbac has already prepared an rpm packages for CentOS so the installation is really simple.
The installation of the module of course is dependant on the exact Linux architecture you’re installing it on.
David has done a great work preparing the rpm packages for both x86 and x86_64 CentOS.
Even better he has prepared packages for both CentOS 4 and 5 releases.

Here is what the uname command returns on the CentOS server where I install the module.

Linux centos 2.6.18-128.7.1.el5 #1 SMP Mon Aug 24 08:21:56 EDT 2009 x86_64 x86_64 x86_64 GNU/Linux

Here is how I did the install in a really simple and quick way on a CentOS 5 runing an x86_64 CentOS release:
1. Download the prepackaged rpm of mod_antiloris in rpm for CentOS from this link

1. Install it using the command

[root@centos-server~ ]# rpm -ivh mod_antiloris-0.3-2.el5.hrb.x86_64.rpm

2. Check the configuration syntax is fine

[root@centos-server~ ]# /etc/init.d/httpd configtest

3.Restart the Apache webserver [root@centos-server~ ]# /etc/init.d/httpd restart

Test it using the slowloris script issuing the command:

[root@centos-server~ ]# perl slowloris.pl -dns yourdomainname.com -port 80 -timeout 1 -num 300 -cache

On my installation it worked like a charm you don’t need to do any configuration settings or anything for slowloris to takeaffect just the Apache restart as marked above is all necessary to load the anti slowloris module on your CentOS Linux.
In case need to install the mod antiloris to another architecture than the one described in this article, just download theappropriate rpm centos version from the list below:

Download links to rpm packages of mod antiloris for x86 and x86_64 for Centos 5.

Download mod_antiloris rpm CentOS5 x86

Download mod_antiloris rpm CentOS5 x86_64

Download mod_antilrois rpm CentOS4 x86

Download mod_antiloris rpm CentOS4 x86_64

Of course this is just one of they ways you can do it. You can always use mod_qos or something similar as well as I’ve mentioned in one of my previous posts.
Here is also an article on How to defend from slowloris Denial of service using mod_qos on CentOS

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Tags: Installing mod antiloris on x86 and x86_64 bit CentOS 4 and 5 to protect from the recent slowloris DoS attack

This entry was posted on Wednesday, May 12th, 2010 at 2:05 am and is filed under System Administration. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.