Delivery to the following recipient failed permanently, Verification failed

Today, I was getting the following error while trying to send email to any account of the server. The mail bounced with the following error messages.
This is an automatically generated Delivery Status Notification
Delivery to the following recipient failed permanently:
test@mydomain.com
Technical details of permanent failure:
Google tried to deliver your message, but it was rejected by the [...]

Effective Solutions for 500 error (Premature End of Script Headers)

There may a number of reasons and solutions for it. We listed a few here for your conveniences.

File/Directory Permission

error: directory is writable by others: (/home/user/public_html/)
This could be easily fixed by just changing the permissions of the file/directory in question. You can change the permissions by using the File Manager within cPanel, or an FTP [...]

Installing Suhosin by Patching PHP Source

Preparation
When you want to install PHP with the Suhosin-Patch you have to first perform some preparation steps.

Step 1: Installing the Hardened-PHP Project Signaturekey
You should first grab a copy of the Hardened-PHP Project’s Release Signaturekey and import it into your GNU Privacy Guard keychain. (For further information on the usage of gnupg please consult it’s [...]

Installing Suhosin as PHP Extension in Linux

Unlike the Hardening-Patch for PHP, nearly all of Suhosin´s features are within the extension. Therefore you might want to only install the extension and use a plain unpatched PHP. Depending on the system we might already offer binary packages. You can check our Suhosin Downloads page. In that case you only need to activate the [...]

Secure your Linux Servers

Securing a linux server is a continuous job as new types of exploits are discovered almost everday. Here, we tried to collect a number of quick guides that will help you securing your linux box.However, this guide covers only basic linux server security tips intended for linux learners. I am writing this [...]

Installing and configuring monit to monitor your server(s)

Monit is a utility for managing and monitoring, processes, files, directories and filesystems on a UNIX system. Monit conducts automatic maintenance and repair and can execute meaningful causal actions in error situations.
Pre Install Step:
yum install openssl*

Step 1: Installing monit from Source
cd /usr/local/src
wget http://mmonit.com/monit/dist/monit-5.0.3.tar.gz
tar -zxvf monit-5.0.3.tar.gz
cd monit-5.0.3
./configure –sysconfdir=/etc/monit/
make && make install

Step [...]

Hardening/Securing SSHD (Secure SHell Daemon)

A quick guide on how to secure your sshd. Hope it helps.
Step 1: First of all we need to make a regular user, since we are disabling direct root login:
adduser admin && passwd admin

Step 2: Backup your current sshd_config
mv /etc/ssh/sshd_config /etc/ssh/sshd_config.bak

Step 3: Create a new sshd_config file

DoS Protection via APF, BFD, DDOS and RootKit

Being a web host, your servers are constantly being attacked by hackers by denial-of-service (DoS) and other brute force attacks. There is no foolproof method to stop 100% of all attacks, but there are ways to protect your servers by applying firewall rules, and detecting and banning attacking IPs.
This article makes use of the [...]

Adding custom directives to VirtualHosts

You can add extra settings for virtual hosts of a domain using DirectAdmin. Simple follow these steps:

Go to Admin Panel -> Admin Settings -> Customize Httpd Configurations.
Click the domain from the list that you want to insert the extra httpd.conf code to.
At the bottom of the page, you’ll see the current httpd.conf for that User. [...]

Installing DirectAdmin in dedicated server

Before you start install of DirectAdmin, make you everything is ready.
Check Prerequisites:

Check your OS and Hardware are capable of running DirectAdmin. Click here for details.
At least one external IP address (NAT/LAN-based systems will NOT work).
You have SSH, gcc and g++ installed. (Quick note: yum install gcc g++ or apt-get install gcc g++)
Make sure your license [...]