October 2011 Issue of Linux Journal: Networking

SneakerNets and BNC Terminators

I first started my sysadmin career about the time in history when 10BASE2 was beginning to see widespread adoption. ThinNet, as it also was called, meant an affordable transition from the SneakerNet so many businesses used. (SneakerNet is a term for walking floppy disks back and forth between computers—not really a network, but it’s how data was moved.) Anyone who remembers those years knows ThinNet was extremely vulnerable to system-wide failures. A single disconnect (or stolen BNC terminator cap at the end of the chain) meant the entire network was down. That was a small price to pay for such inexpensive and blazing-fast speed. 10Mbit was the max speed ThinNet supported, but who in the world ever would need that much throughput?

Networking has changed a lot since my career started, and it’s issues like this one that keep me up to date. Kyle Rankin starts off with a hacking primer using an off-the-shelf home router (follow this link to read the full article now-- it's open to all as a free preview of this October issue). This isn’t merely the old WRT54G hacks you’re used to reading about. Instead, Kyle shows us how to don our black hats and really hack in to a D-Link wireless 802.11n router. If Kyle’s hacking tutorial makes you a little nervous, don’t worry; we have some network security this month as well. Henry Van Styn teaches us some advanced firewall configurations with ipset. Granted, firewalls won’t protect anyone from PHP vulnerabilities, but they still help me sleep better at night.

Mike Diehl switches gears, and instead of showing how to hack (or protect) the network, he describes how to create. Specifically, he explains how to create network programs that are cross-platform and easy to build with ENet. As someone whose programming skills peaked with 10 GOTO 10, Mike’s idea of “easy” might be relative, but he gives coding examples, so even copy/paste programmers can join in.

Henry Van Styn has another article in this issue on how to use tcpdump to troubleshoot network issues effectively. If you’re in charge of a large network, you owe it to yourself to polish your tcpdump skills. It’s a tool every network administrator needs, and Henry takes some of the mystery out of it. Adrian Hannah follows in a one-two punch teaching us how to sniff packets effectively. Packet sniffing is one of those skills that can be used for good and evil both, but we’ll assume you’ll use your powers for good. At the very least, you’ll understand what sort of information is available on your network so you can try to secure it a bit.

Networking also has made so many other facets of computing possible. If it weren’t for networking, we wouldn’t have cloud computing. Adrian Klaver shows how to use Python to work with Amazon Web Services. For some of you, cloud computing is scary, because you never get to access the computer you’re working on directly. One way to help alleviate the concern of working on computers far away is to implement remote viewing. Joey Bernard covers several methods for accessing a computer remotely, whether it’s in the next room or on the next continent. Granted, that doesn’t work for cloud-based services, but it does for remotely hosted servers, so it’s an article you’ll want to check out.

Our networks are even home to filesystems nowadays, and Petros Koutoupis shows how to deploy the Lustre distributed filesystem. Utilizing multiple nodes for file storage is a great way to leverage your network resources for speed and redundancy. Regardless of your network speed, however, data will travel only as quickly as the hard drive underneath will send it. Kyle Rankin reviews the Intel 320 series SSD this month. If you haven’t taken the plunge to SSD, after reading about his results, you might decide that now is the time.

And, of course, for those of you who think networking is good only for accessing your e-mail, we have articles for you this month too. Programmers will like Reuven M. Lerner’s article about his mustache—more specifically, Mustache.js, a JavaScript templating system that might be right up your alley. Dave Taylor shows us scripters how to manipulate image files without ever leaving the command line. There’s nothing wrong with firing up The GIMP to edit a graphic file, but sometimes you just want to scale an image quickly. Dave explains how.

We’ve also got new product debuts, Linux news and interesting things I’ve stumbled across this month in the UpFront section. So whether you’re carrying this issue around on a Flash drive (SneakerNet anyone?) or downloading it wirelessly from the wireless router you just hacked, we hope you enjoy it. We certainly enjoyed making it.

Linux Journal October 2011 Issue #210

Editorial Focus: Networking

Available to Subscribers: October 1

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