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Domain Name Service (DNS) was created in 1983 out of the necessity to convert IP Addresses like 192.168.9.2 to domain names like example.com. DNS is a distributed database, what this means is that no one computer is used to maintain a complete database of all of the domains on the Internet. Instead this information is distributed across many computers. To further understand how this works, take a look at the DNS structure:

When SSL is used with Apache via the mod_ssl module, it will create an encrypted RSA file which has two components a private file which is kept secure on the server and a public file which is placed in the Certificate file and is thus used by users when they connect to the server. Users will be able to communicate securely then using the encryption that results in this kind of communication. New standards are requiring a 2048-bit key instead of the older 1024-bit key.

The major goal of the regional server is to distribute the results of all service checks to the central server. The regional Nagios machines must use OCSP and OCHP in order to send the proper updates to the central server. This tutorial shows you how to set one up.

Outsourcing allows you to create a solution to a specific problem quickly. Many of the solutions that you may want to deploy in your organization require skills that take years to develop. Outsourcing helps you leverage the time factor.

This is part two of a three part series on distributed monitoring. You can use passive service and host checks to allow non-central Nagios servers to collect data from a network of machines and then transfer that information to a central Nagios server. The transfer of information is done using NSCA so that the central Nagios server will receive the data from the External Command File interface and process the information as a passive check.

Configure Microsoft Outlook Express with TLS and SMTP_AUTH. This is a common issue that can be overlooked by administrators for users who insist on using Outlook Express. The set up for secure login and sending email is not intuitive.

The primary goal of a backup machine for Postfix is that if the first one fails, mail will be collected by the secondary mail server until the primary mail server is back online. When you build the Backup MX be sure to install all of the necessary applications to scan for viruses and check for SPAM as you do not want to overload the primary machine once it comes online.

Kerberos provides a secure network authentication model using secret-key cryptography. Kerberos can be used with multiple services to offer superior authentication security. On a Centos system you can review a list of possible programs that are listed for kerberos with yum. yum list | grep krb5

The Network Information Service distributes information on the network that must be shared between the Linux machines. Sun Microsystems developed a system known as Yellow Pages (YP) that eventually became known as NIS. The original YP is added to most commands for NIS ypserver, ypbind, and yppasswd. Typically NIS is used to distribute information about the users and how they authenticate to Linux.

Many administrators who use Postfixadmin, a web based tool to manage virtual domains on Postfix, would like to secure the transactions between the PostfixAdmin program and the administrator. At the same time often you do not want to add the extra burden of SSL on the whole domain but just want to secure one directory. The solution is to create a certificate for that one directory only and also locking that directory with a password so only administrators can gain access. The example is on an Ubuntu 9.10 server, which will be very similar to most server procedures.

I've been looking for a lightweight distribution to use on my Dell desktop with older hardware. While searching for a worthy candidate I almost immediately ran across last week's release of PC/OS 10. With a familiar Ubuntu base and new improvements such as Google Chrome and Skype, I thought PC/OS 10 Webstation was worth a look.

The Ubuntu server is the most innovative distribution for servers. It enables administrators to gain access to cutting edge technology and implement that with new ideas. If you are looking for the latest and greatest, this is the server option for you.

There are a number of popular choices for Linux enterprise level servers including CentOS, Ubuntu, Debian, Slackware and others including Red Hat Enterprise. What is important to recognize in this evaluation is that how you view advantages and disadvantages are dependent upon the expertise of your Linux administrators and the level of support you need to maintain your servers.

There are several reasons you may want to create a local repository. The first is that you want to save on bandwidth if you have multiple Ubuntu machines to update. For example if you had 25 Ubuntu machines that all needed updating at least once a week, you would significantly save bandwidth because you could do all but the repository locally.

Alot of people ask me the easiest way to record their experiences while using Ubuntu. You can do this several ways but using an application named recordMyDesktop seems to be the most popular method. This video tutorial will show you how to install recordMyDesktop, create a video in .ogv format, and convert it to an .avi.

If you're a KDE fan but haven't taken Pardus Linux out for a spin in awhile, maybe it's time you should. Yesterday brought us Pardus 2009.1 which features the new hybrid .iso files, one of the easiest installers around in YALI, a sweet KDE 4.3.4 desktop, and a growing number of available applications. I gave the new version of Pardus a shot and here's what I found.

An excellent program for monitoring users and applications is psacct. This program will work in the background of your system recording what all users are doing on your system as well as the resources that are being consumed. I originally started using this program when a client asked for a way to monitor his developers and what they were doing on the servers that they were working on.

A few tips I put together while re-creating the robots.txt file on my Linux web server. The robots.txt is used to provide crawling instructions to web robots using the Robots Exclusion Protocol. When a web robots visits your site it will check this file, robots.txt, to discover any directories or pages you want to exclude from the web robot listing on the search engine. This is an important file which determines SEO for search engines and can help rankings.

For me, the hardest part about teaching the LPI 101 course is teaching about text-stream filters. It’s not that they’re difficult to understand. It’s just that showing the examples of how they work is easy, but showing examples of how they can be used in real life is a bit more challenging. Real-life examples from the Linux admin world are fairly complex, and are beyond the level that most beginning Linux students are able to grasp. So, in most LPI books, the student will see how these utilities work, but not how to use them.

Tips for Linux administrators entering and moving through today’s Linux admin market as traditional qualifications become less relevant and the need for real skills increases.