An Introduction to Web Servers: Part 2

A web server will typically run as a daemon (system service) under a single application process. That initial process will then spawn child processes that handle virtual servers, individual websites, or even individual requests. As such, a web server could spawn hundreds or even thousands of processes per day, per hour, or even […]

Back to the Basics #6: Network Security

In order for a network to be secure, you need to have some type of firewall in place. Firewalls typically protect your server from a wide variety of network attacks, all of which focus on weaknesses or holes in your network. For example, an cyber-criminal may scan your server for an open, unused port and […]

Should You Offer SSH Access?

With a Linux or Unix dedicated server, you will probably access it via SSH on a regular basis. It is an essential feature for server system administrators. For other users, however, it is usually not essential and may even be a security risk. Do your hosting customers or company employees need access? A lot of […]

Connecting to MySQL from a Remote Location

The most common way to work with and manage MySQL is directly, using the command line or a web-based tool such as phpMyAdmin.  If, however, you have more than one database server or need to do routine complex tasks, the former may be too tedious, and the latter may be too simple.  Another possible reason […]

How to Change Your SSH Port with SELinux (RHEL 6)

In a previous post, we explained how to change the SSH port on your Linux server from the standard port 22.  In most cases, this works just fine, but if you are using Red Hat Enterprise Linux 6, there is a good chance you received an error such as […]

How to Change Your Server’s SSH Port

By default the Linux SSH server (usually OpenSSH) listens for connections on port 22.  Everyone knows this, including hackers.  If you have other security measures in place, it may not matter if would-be attackers know your SSH port.  Nevertheless, having SSH on another port other than the default may add […]

Using Netstat to Monitor Network Services

Monitoring your dedicated server is a good way to prevent attacks, crashes, and other problems that invariably creep up.  Although there are many external tools to help you monitor your server, Linux-powered servers also have plenty of internal tools that can help you with both monitoring and troubleshooting.
Netstat is a small network tool that can […]

4 Tips to Secure Apache Web Servers

Having an ironclad firewall for your dedicated server is only part of the equation when it comes to security. Certain ports on your server must remain open in order for it to function, and any open port is a potential target for would-be attackers. Port 80, the standard HTTP port used by Apache, […]

More Port Analysis with lsof

Last week we looked at two Unix/Linux commands that you can use to find out more information about open ports and the processes running on them. Another useful tool for process analysis is “lsof”, which stands for “list open files”. The command itself can be used for many tasks on your dedicated […]

Listening for Programs on Server Ports

On a Linux or Unix dedicated server, applications that access the Internet must do so using ports. Think of a port, as the name implies, as a window to the outside world. Without a port, a program will not have outside access, and outside computers will not have access into your server.
When configuring […]

What is a Brute Force Attack?

Server security can be complex and time consuming. Therefore, even if you are not responsible for your server’s security, it is a good idea to know security terminology. A brute force attack occurs when a hacker attempts to gain access to a dedicated server or VPS using a standard login (SSH, mail server, […]

Running a Second Instance of Apache

One of the benefits of Apache HTTP Server is that you can run multiple instances of it as virtual hosts (as in shared hosting scenarios). In some cases, you may want a public instance of Apache for an IP address/domain and then another private instance running on a separate port. On […]

How to Change Your Server’s FTP Port

By default, most dedicated servers use port 21 as their FTP (File Transfer Protocol) port. Most FTP clients also recognize this port out of the box, without any configuration necessary. For the majority of your server needs, you will want to leave the default port as is.
In a few unique situations, however, you […]

How to Change the Port Number in Postfix

The default network SMTP port for Postfix, Sendmail and most other mail servers is 25. This is the port used to send email, and most email clients will use it by default. Unfortunately, some Internet service providers have started to block port 25 because of the high volume of spam sent through it. […]