Linux Journal July 2012

A quick overview of what's in this special Networking issue:

* Build a UML Network and Debug Kernel Modules
* Start Sharing--Make a PirateBox Device
* Reduce Latency for TCP-Based Applications
* Engineer an OpenLDAP Directory
* Increase Your Scripting Efficiency with Subshells

Detailed overview: Cast the Nets!

I thought we'd gone native this month and were going to show how to work
nets and fish like the penguins do. I had a double-fisted, sheep-shanked,
overhand cinch loop to teach you, along with the proper way to work your net
in a snow storm. As it turns out though, it's actually the "networking" issue. That's still pretty cool, but instead of the half hitch, you get a crossover
cable, and instead of my constrictor knot, you get load balancing.

Reuven M. Lerner starts out the issue with an article on Pry. If you're a Python programmer using iPython, you'll want to check out its Ruby counterpart, Pry. Although it's not required for coding with Ruby, it makes life a lot easier, and Reuven explains why. With a similar goal of improving your programming skills, Dave Taylor shows how to use subshells in your scripting. This doesn't mean you can't continue to write fun scripts like Dave's been demonstrating the past few months, it just means Dave is showing you how to be more efficient scripters. His tutorial is a must-read.

I got into the networking theme myself this month with a column on Webmin.
Some people consider managing a server with Webmin to be a crutch, but I see it as a wonderful way to learn system administration. It also can save you some serious time by abstracting the underlying nuances of your various server types. Besides, managing your entire server via a Web browser is pretty cool. Speaking of "pretty cool", Kyle Rankin finishes his series on
3-D printing this issue. The printer itself is only half the story, and Kyle
explains all the software choices for running it.

If Webmin seems a little light for your networking desires, perhaps Ratheesh
Kannoth's article on the reconnaissance of the Linux network stack is more
up your alley. Ratheesh peels back the mystery behind what makes Linux such a powerful and secure kernel, and does it using UML. If that sounds
confusing, don't worry; he walks you through the entire process.

If you're actually creating or tweaking a network application, Andreas
Petlund's article on TCP thin-stream modifications will prove invaluable.
Anyone who ever has been fragged by an 11-year-old due to network latency
knows a few milliseconds can be critical. Certainly there are other applications that rely on low network latency, but few are as pride-damaging as that. Andreas shows how to tweak some settings in the kernel that might make the difference between fragging or getting fragged. Unfortunately, no amount of tweaking can compare with the fast reflexes of an 11-year-old—for that you're on your own.

Stewart Walters picks up his OpenLDAP series from the April issue, and he demonstrates how to manage replication in a heterogeneous authentication environment. OpenLDAP is extremely versatile, but it still runs on hardware. If that hardware fails, a replicated server can make a nightmare into a minor
inconvenience. You won't want to skip this article.

If my initial talk of fishing nets, knots and the high seas got you
excited, fear not. Although this issue isn't dedicated to fish-net-working,
my friend Adrian Hannah introduces the PirateBox. If the Internet is too
commonplace for you, and you're more interested in dead drops, secret Wi-Fi
and hidden treasure, Adrian's article is for you. The PirateBox doesn't
track users, won't spy on your family and won't steal your dog. What it
will do is share its digital contents to anyone in range. If your interest
is piqued, check out Adrian's article and build your own. Yar!
--Shawn Powers