Archive for July, 2010


Linux Server Memory Usage

If you are mostly familiar with Windows computers, you may find the way your Linux dedicated server uses memory to be odd or even alarming. When I first started using Linux on a server, it was a bit disconcerting to see Linux use up all of the available RAM. This is much different […]

Manage Web Images with ImageMagick

ImageMagick is a powerful software suite that gives users the ability to create, manipulate, and process images in a variety of formats, including JPEG, TIFF, and PNG. It comes with a collection of command line tools for batch image conversion and many other tasks. It also serves as a frontend for a […]

Who is the user Nobody?

If you stare at the list of running processes on your server for long enough, you are bound to come across the user called “nobody”. Before you call a security expert and prepare to fight off a hacker, relax. While the username “nobody” may seem suspicious, it is actually supposed to be there.
On […]

Anonymous FTP: Benefits and Disadvantages

FTP (File Transfer Protocol) servers normally require authentication. A user must login, providing a username and password, and the session will last only as long as the user stays logged in.
Anonymous FTP provides users with the ability to access an FTP server without providing password authentication. At first glance, this may sound insane, […]

Mail Delivery Problems: Your Server May Not Be to Blame

The seemingly endless number of possible mail server configurations is no surprise for most IT support personnel. Whether an organization is operating on a shoestring budget or is well-funded, mail servers are often crammed with unnecessary applications that take up too many precious resources. This dubious practice can cause the mail server to perform poorly […]

32-bit vs 64-bit Dedicated Servers

64-bit architecture is not something new, but there are still a lot of 32-bit computers on the market. While high-end servers almost always have 64-bit Xeon, AMD64, Itanium, or PowerPC processors, when starting out, you may be faced with the choice between 32-bit or 64-bit. Which should you choose?
Before you decide, you should […]

Protect Your Server with APF Firewall

Protect Your Server with APF Firewall
There are many firewall solutions out there, and I do not pretend to be an expert on security. Nevertheless, I can testify from experience that some solutions are easier, more secure, and more affordable than others. APF (Advanced Policy Firewall) from R-fx Networks is one solution that […]

The ps Command on a Linux Server

One of the important tasks you should regularly perform when managing your dedicated server, is to monitor the running processes. While the “top” command will provide you with a glimpse of the most active processes, the “ps” command can give you all of them or the specific ones you want.
As an introduction to ps, […]

How to Remove Trojan.JS.Redirector.cq from Your WordPress Site

I had seen a post on Twitter about a bunch of MediaTemple accounts getting infected with this virus a few days ago, and it’s no surprise that the host hasn’t done anything about it yet. When I went to a client’s website during a call, Kaspersky caught the malicious code right away. Having a […]

Configuring the Date on a Linux Server

When running a VPS or leased dedicated server, you may find that the timezone does not match your own. You may or may not also find that your new server has the correct date. With Linux servers, you can change the date and timezone with a few simple commands.
Why is this important? […]

Test Your Server OS with VirtualBox

When you get your first dedicated server, the last thing you want to do is experiment on it, especially if your server is already live on the Internet. Instead, you can use a virtual machine to run the same operating system installed on your server. With it you can do whatever kind of […]

PHP Command Line Interface

PHP is a versatile tool that millions of sites use to power their content management systems and user interfaces. Its flexibility and dynamic nature make it deal for the era of the Internet that has been dubbed “Web 2.0”. It is, therefore, no surprise that the highly praised LAMP (Linux+Apache+MySQL+PHP) stack includes PHP.
What […]

Secure Apache Server with ModSecurity

Your server’s security is a top priority. After all, you have undoubtedly spent a good deal of time and money acquiring, configuring, marketing, and optimizing your server. The moment it connects to the Internet, however, it has entered a hostile environment.
The first line of defense on any server is the network firewall. […]

What is DNSBL and Why Should I Care?

DNSBL stands for DNS Blacklist or Block List and is a list of IP addresses, distributed throughout the Internet, identifying computers or networks accused of spamming. Many web hosts and Internet service providers (ISP) use these blacklists in their anti-spam filters to help keep spam from reaching their users.
DNSBL have received mixed reviews and […]

Nameserver Subnet Warnings

When you setup a new dedicated server, nameservers are some of the most important components. Without nameservers, your server’s websites cannot connect to the outside world. Any type of nameserver errors should be addressed immediately. The following error is a common one:
WARNING: Not all of your nameservers are in different subnets
If you […]

Reduce Client Security Holes with Automated Script Installers

Your server is like your baby, and no one wants to see their baby crash, get kidnapped, freeze up, get attacked, or contract a deadly virus. One way you can lessen the possibility of security compromises on your server is to provide your web hosting clients with script installation services.
A lot of security holes […]

What to Do When You’re Accused of Spamming

No matter what precautions you take or how many hours, days, or even weeks you have spent hardening your server’s security, the possibility of being accused of sending spam still exists. This can cause you all kinds of problems, from the inability to send mail to certain Internet Service Providers (ISP), to having your […]

Incremental Backup with Rsync

Few things are more important to a dedicated server than incremental backups. When your server is your livelihood and your reputation depends on it being reliable, you need to be prepared for possible disasters. Backups ensure that you always have a plan B, should something go wrong with your server.
To perform backups, you […]

Restrict SSH User Access to System Files

For most shared hosting accounts, you will not give your users SSH access, but there are situations where you might. In those unique situations, you need to make sure that the SSH user cannot frolic freely throughout the filesystem, viewing files that should be restricted to the server administrator.
Unfortunately, there is no easy way […]

Jail FTP Users to Their Home Directories

Even if you trust your users not to purposefully hack your server, allowing them to peruse your entire file system of your dedicated server whenever they want is definitely a bad idea.
On most Linux distributions, the normal users do not have permissions to make any changes to system directories like /etc /var and /usr, but […]

Linux Servers: In-box Upgrade vs. Fresh Install

Linux users have long debated whether it is better to perform an in-box upgrade or completely wipe a system clean and reinstall whenever there is a new major version release.
For desktop Linux users, the answer is matter of convenience. For server administrators, it can make or break a career or business.
Many Linux […]

How to Control Linux Services

A service or daemon is a memory-resident program that runs in the background. Your operating system will typically start it at boot (although not always) and continue to run it without any intervention on your part. Some common services usually running on a Linux dedicated server are: web server (such as Apache), database […]

How to Setup an SSH Key

An SSH key is a highly encrypted code that allows you to connect from one server to another, without having to send the password over the network. Because it is encoded, there is less of a chance that hackers will be able to snatch your password and gain unlawful access to your server.
To begin […]

What is PHP Safe Mode?

The general term “safe mode” refers to a state in which a software application has been stripped to its bare minimum configuration, usually in order to troubleshoot stability or security issues. Windows users who have experienced any type of serious system anomalies have undoubtedly been forced to boot into safe mode at one time […]