Not So Dynamic Updates

Typically when a network is under my control, I like my servers to have static IPs. Whether the IPs are truly static (hard-coded into network configuration files on the host) or whether I configure a DHCP server to make static assignments, it's far more convenient when you know a server always will have the same IP. more>>

Posted by on 30 March 2015 | 11:33 am

Users, Permissions and Multitenant Sites

In my last article, I started to look at multitenant Web applications. These are applications that run a single time, but that can be retrieved via a variety of hostnames. more>>

Posted by on 26 March 2015 | 12:28 pm

New Products

Please send information about releases of Linux-related products to newproducts@linuxjournal.com or New Products c/o Linux Journal, PO Box 980985, Houston, TX 77098. Submissions are edited for length and content.

Posted by on 24 March 2015 | 1:13 pm

Flexible Access Control with Squid Proxy

Large enterprises and nuclear laboratories aren't the only organizations that need an Internet access policy and a means of enforcing it. My household has an Internet access policy, and the technique I've used to enforce it is applicable to almost any organization. In our case, I'm not too concerned about outside security threats. more>>

Posted by on 23 March 2015 | 3:10 pm

Solving ODEs on Linux

Many problems in science and engineering are modeled through ordinary differential equations (ODEs). An ODE is an equation that contains a function of one independent variable and its derivatives. more>>

Posted by on 19 March 2015 | 12:28 pm

DevOps: Everything You Need to Know

Have projects in development that need help? Have a great development operation in place that can ALWAYS be better? more>>

Posted by on 19 March 2015 | 9:13 am

Tighten Up SSH

SSH is a Swiss Army knife and Hogwart's magic wand all rolled into one simple command-line tool. As often as we use it, we sometimes forget that even our encrypted friend can be secured more than it is by default. For a full list of options to turn on and off, simply type man sshd_config to read the man page for the configuration file. more>>

Posted by on 18 March 2015 | 5:06 pm

Security in Three Ds: Detect, Decide and Deny

Whenever a server is accessible via the Internet, it's a safe bet that hackers will be trying to access it. Just look at the SSH logs for any server you use, and you'll surely find lots of "authentication failure" lines, originating from IPs that have nothing to do with you or your business. more>>

Posted by on 16 March 2015 | 1:21 pm

Non-Linux FOSS: MenuMeters

It sounds like a "back in my day" story, but I really do miss the days when laptops had LED activity lights for hard drives and Wi-Fi. Sure, some still have them, but for the most part, the latest trend is to have no way of knowing if your application is pegging the CPU at 100%, or if it just locked up. more>>

Posted by on 12 March 2015 | 3:02 pm

Android Candy: Bluetooth Auto Connect

I love my latest Android device (see the March 2015 issue's Open-Source Classroom column for details), but for some reason, it won't automatically connect to my Bluetooth headset. When I turn on my headset, I want it to connect to my Android device so I can start using it right away. more>>

Posted by on 11 March 2015 | 1:36 pm

diff -u: What's New in Kernel Development

Nicolas Dichtel and Thierry Herbelot pointed out that the directories in the /proc filesystem used a linked list to identify their files. But, this would be slow when /proc directories started having lots of files, which, for example, might happen when the system needed lots of network sockets. more>>

Posted by on 9 March 2015 | 1:26 pm

Geek Guide: The DevOps Toolbox

When I was growing up, my father always said, "Work smarter, not harder." Now that I'm an adult, I've found that to be a core concept in my career as a DevOps engineer and manager. In order to work smarter, you've got to have good tools and technology in your corner doing a lot of the repetitive work, so you and your team can handle any exceptions that occur. more>>

Posted by on 6 March 2015 | 10:54 am

Nmap—Not Just for Evil!

If SSH is the Swiss Army knife of the system administration world, Nmap is a box of dynamite. It's really easy to misuse dynamite and blow your foot off, but it's also a very powerful tool that can do jobs that are impossible without it. more>>

Posted by on 5 March 2015 | 3:15 pm

Resurrecting the Armadillo

1999 was a crazy year for business on the Internet, and for Linux. It was when Red Hat went public, with a record valuation, and VA Linux followed with a bigger one. Both were cases in point of the dot-com boom, a speculative bubble inflated by huge expectations of what the Internet would mean for business. more>>

Posted by on 4 March 2015 | 2:19 pm

March 2015 Issue of Linux Journal: System Administration

System administration is a very general term. It's our job to fix problems, repair systems and remind people to try power cycling their troubled desktops. more>>

Posted by on 2 March 2015 | 10:38 am