Block an IP to Speed up Server During DOS Attack

If your Apache server is slow (or if you see tons of “? ..reading..” on Apache Status in WHM) there is a chance that your http server is under a Denial of Service (DOS) attack.
You can check this out by:

Log on your server as root
Type the following command

Fix Open Nameservers to Speed up Sites and Prevent DOS

Open nameservers allow anyone in the world to perform queries on them, which can often lead to DOS attacks and slower performance. Most system administrators prefer to have their nameservers restricted and used only by trusted parties. To check your namesevers, use Intodns, a free tool! 
To do this kind of setup, you will need [...]

Install APF Firewall For Server Security

A firewall is essential for the security of any server. Below are the steps to setting up APF on your system to control access:
Download and install APF:

cd /usr/src
wget http://www.rfxnetworks.com/downloads/apf-current.tar.gz
tar -xvzf apf-current.tar.gz
cd apf-*
./install.sh

Email Deliverability Fixes Part 1:SPF

If you, like me, suffer(ed) from a lot of soft-bounced emails because your server was misconfigured, then this guide is perfect for you! If you run a dedicated server with WHM/Cpanel and cannot get mass mails to deliver, try this guide.
In part one you will learn how to install SPF to all of your domains, [...]

Rootkit Removal Guide

This should work on all *nix operating systems.
Chkrootkit “is a tool to locally check for signs of a rootkit” (from http://www.chkrootkit.org).
“The Sentry tools provide host-level security services for the Unix platform. PortSentry, Logcheck/LogSentry, and HostSentry protect against portscans, automate log file [...]

Random JS Rootkit/Rootkits in General

Most of you are aware of the recent exploit that has hit the Linux work, but for those of your that aren’t I’ll be posting a quote from an announcement from cPanel.com. Please note that I don’t totally agree with them on this for now.
A server compromise trend has been recently reported targeting multiple hosting [...]