HOW-TOs

Dr Hjkl on the Command Line

The first time I used vi was in a college programming course. It was the default editor on the computer lab's UNIX systems we used to compile our assignments. I remember when our professor first introduced vi and explained that you used the hjkl keys to move your cursor around instead of the arrow keys. more>>

Using Hiera with Puppet

With Hiera, you can externalize your systems' configuration data and easily understand how those values are assigned to your servers. With that data separated from your Puppet code, you then can encrypt sensitive values, such as passwords and keys. more>>

It's Easier to Ask Forgiveness...

...than to understand Linux permissions! Honestly though, that's not really true. Linux permissions are simple and elegant, and once you understand them, they're easy to work with. Octal notation gets a little funky, but even that makes sense once you understand why it exists.

Users and Groups: more>>

Picking Out the Nouns

A reader wrote a letter to me (oh happy day!), and although I'm still not entirely sure what she's trying to accomplish, it's an interesting puzzle to try to tackle anyway. Here's what she asked: more>>

Return of the Mac

In a previous article, I talked about vim macro basics. In that article, I described how to record a custom macro, assign it to a key and then use it to make automated edits to a BIND zone. I also teased that I would cover more advanced uses of macros, like nested macros, in a future issue. more>>

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>>

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>>

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>>

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>>

High-Availability Storage with HA-LVM

In recent years, there has been a trend in which data centers have been opting for commodity hardware and software over proprietary solutions. Why shouldn't they? It offers extremely low costs and the flexibility to build an ecosystem the way it is preferred. The only limitation is the extent of the administrator's imagination. more>>

DNSMasq, the Pint-Sized Super Dæmon!

I've always been a fan of putting aftermarket firmware on consumer-grade routers. Whether it's DD-WRT, Tomato, OpenWRT or whatever your favorite flavor of "better than stock" firmware might be, it just makes economic sense. Unfortunately, my routing needs have surpassed my trusty Linksys router. more>>

Localhost DNS Cache

Is it weird to say that DNS is my favorite protocol? Because DNS is my favorite protocol. There's something about the simplicity of UDP packets combined with the power of a service that the entire Internet relies on that grabs my interest. Through the years, I've been impressed with just how few resources you need to run a modest DNS infrastructure for an internal network. more>>

Days Between Dates: the Counting

In my last article, we began an exploration of date math by validating a given date specified by the user, then explored how GNU date offers some slick math capabilities, but has some inherent limitations, the most notable of which is that it isn't on 100% of all Linux and UNIX systems. more>>

Real-Time Rogue Wireless Access Point Detection with the Raspberry Pi

Years ago, I worked for an automotive IT provider, and occasionally we went out to the plants to search for rogue Wireless Access Points (WAPs). A rogue WAP is one that the company hasn't approved to be there. So if someone were to go and buy a wireless router, and plug it in to the network, that would be a rogue WAP. more>>

Days Between Dates?

Alert readers will know that I'm working on a major revision to my popular Wicked Cool Shell Scripts book to come out later this year. Although most of the scripts in this now ten-year-old book still are current and valuable, a few definitely are obsolete or have been supplanted by new technology or utilities. No worries—that's why I'm doing the update. more>>

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