Category: HOW-TOs

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:



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>>


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>>


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


Synchronize Your Life with ownCloud

Like most families these days, our family is extremely busy. We have four boys who
have activities and appointments. My wife and I both have our own businesses as
well as outside activities. For years, we’ve been using eGroupware to help
coordinate our schedules and manage contacts. The eGroupware system has served us
well for a long time. However, it is starting to show its age. more>>


An Introduction to OpenGL Programming

OpenGL is a well-known standard for generating 3-D as well as 2-D graphics
that is extremely powerful and has many capabilities. OpenGL is defined
and released by the OpenGL Architecture Review Board (ARB).

This article is a gentle introduction to OpenGL that will help you
understand drawing using OpenGL.


Easy Watermarking with ImageMagick

Let’s start with some homework. Go to Google (or Bing) and search
for “privacy is dead, get over it”. I first heard this from Bill
Joy, cofounder of Sun Microsystems, but it’s attributed to a number of
tech folk, and there’s an element of truth to it. Put something on-line
and it’s in the wild, however much you’d prefer to keep it under