SysAdmin

Ubuntu's New DNS: Unknown Host

If you're the type of person who installs Ubuntu's server edition, you're also likely the sort of person who knows how to configure network settings. For most distributions, especially those based on Debian, the process is a bit strange, but familiar.

Stop Waiting For DNS!

I am an impulse domain buyer. I tend to purchase silly names for simple sites that only serve the purpose of an inside joke. The thing about impulse-buying a domain is that DNS propagation generally takes a day or so, and setting up a Web site with a virtual hostname can be delayed while you wait for your Web site address to go "live".

The Sysadmin's Toolbox: sar

As someone who's been working as a system administrator for a number of years, it's easy to take tools for granted that I've used for a long time and assume everyone has heard of them.

Book Review - The Linux Command Line

Do you ever have that moment when someone asks you for a recommendation on a book, and when put on the spot you spin around in your office chair, scan your ever-growing library of books that you bought over the years of IT experience but either: A. Never read? B. Flipped through but never finished? C.Passed out halfway through the first chapter? 

Ahead of the Pack: the Pacemaker High-Availability Stack

A high-availability stack serves one purpose: through a redundant setup of two or more nodes, ensure service availability and recover services automatically in case of a problem. Florian Haas explores Pacemaker, the state-of-the-art high-availability stack on Linux.

OpenLDAP Everywhere Reloaded, Part I

Directory services is one of the most interesting and crucial parts of computing today. They provide our account management, basic authentication, address books and a back-end repository for the configuration of many other important applications.

Tales From the Server Room: Zoning Out

Sometimes events and equipment conspire against you and your team to cause a problem. Occasionally, however, it's lack of understanding or foresight that can turn around and bite you. Unfortunately, this is a tale of where we failed to spot all the possible things that might go wrong.

Complexity, Uptime and the End of the World

Poorly implemented monitoring systems can drive an administrator crazy. At best, they are distracting. At worst, they'll keep whoever is on pager duty up for nights at a time. This article discusses the best practices for designing systems that will keep your systems up and stay quiet when nothing is wrong.

SSH Tunneling - Poor Techie's VPN

"If we see light at the end of the tunnel, it is the light of the oncoming train" ~ Robert Lowell. Oh yes, another good quote. This post is on SSH tunneling, or as I like to call it 'Poor Man's VPN'. Contrary to the sysadmin's popular belief, SSH tunneling actually can be very valuable use for both techies and home users.

Advanced Firewall Configurations with ipset

iptables is the user-space tool for configuring firewall rules in the Linux kernel. It is actually a part of the larger netfilter framework. Perhaps because iptables is the most visible part of the netfilter framework, the framework is commonly referred to collectively as iptables. iptables has been the Linux firewall solution since the 2.4 kernel.

tcpdump fu

Packet capture is one of the most fundamental and powerful ways to do network analysis. You can learn virtually anything about what is going on within a network by intercepting and examining the raw data that crosses it. Modern network analysis tools are able to capture, interpret and describe this network traffic in a human-friendly manner.

Linux Systems Capacity Planning

This video is from our good friends at USENIX's recent LISA conference in Boston. "Linux Systems Capacity Planning: Beyond RRD and top", by Rodrigo Campos

The Lustre Distributed Filesystem

There comes a time in a network or storage administrator's career when a large collection of storage volumes needs to be pooled together and distributed within a clustered or multiple client network, while maintaining high performance with little to no bottlenecks when accessing the same files. That is where Lustre comes into the picture. The Lustre

Getting Help From Linux - Part 2 Info

Well here we are again, at part two of the 'Getting Help from Linux' series.  In this blog post I'll be talking about using Info to get help from Linux.  In my previous post I spoke about how Info came about, but just in case you missed it I'll give you another quick lesson.  Gnu

Tracking Server Uptimes

Unlike some other OS's, Linux almost never has to reboot… or so I was told when I first started learning about it. To illustrate the point, my mentor introduced me to an app that he ran on all of his servers called uptimed.

Unboxing Day

As much as I love working with Linux and configuring software, one major part of being a sysadmin that always has appealed to me is working with actual hardware. There's something about working with tangible, physical servers that gives my job an extra dimension and grounds it from what might otherwise be a completely abstract job even further disconnected from reality.