SysAdmin

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.

Remotely Wipe a Server

In many ways, I feel sorry for people stuck with proprietary operating systems. When something goes wrong or if they have a problem to solve, the solution either is obvious, requires buying special software or is impossible. With Linux, I've always felt that I was limited only by my own programming and problem-solving abilities, no matter what problem presented itself.

Lock Firefox 6 Prefs (Also versions 3, 4, & 5)

In a corporate environment, it's often important to enforce Internet proxy settings for all users. Setting those options automatically is often difficult. Making them locked and immutable is even more difficult and poorly documented. Today we'll learn the basics, and from there you can customize Firefox as much or as little as you like.

Creating a Centralized Syslog Server

A centralized syslog server was one of the first true SysAdmin tasks that I was given as a Linux Administrator way back in 1997. My boss at the time wanted to pull in log files from various appliances and have me use regexp to search them for certain key words. At the time Linux was still in its infancy, and I had just been dabbling with it in my free time.

It's Always DNS's Fault!

It's always better to learn from someone else's mistakes than from your own. In this column, Kyle Rankin or Bill Childers tells a story from his years as a systems administrator, and the other chimes in from time to time. It's a win-win: you get to learn from their experiences, and they get to make snide comments to each other. Today's episode is narrated by Bill.

Nagging Notifications

In the February 2011 issue, I wrote about screen, the console window manager, and how I configure its hardstatus line to show notifications along the bottom of my terminal window.

Getting Help from Linux - Part 1 Man Pages

man womanNo manual entry for woman Oooh, I just know I'm going to hear it in the comments for that one. But you know what? Just how many of you have tried something similar with other words? You know you have at least once or twice. Go ahead, try one or two..you might be surprised.

Creating Software-backed iSCSI Targets in Red Hat Enterprise Linux 6

Studying for certification exams can be an adventure. Even more so when the certification exam is a hands-on, performance-based exam. The quandry most people I know fall into, is that to effectively study for such an exam, you need access to a lab environment with elements that may be beyond the scope of the average Linux enthusiast. One such element is iSCSI.