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Category Archives for "Russ White"

DoS’ing your mind: Controlling information inflow

Everyone wants your attention. No, seriously, they do. We’ve gone from a world where there were lots of readers and not much content, to a world where there is lots of content, and not many readers. There’s the latest game over here, the latest way to “get 20,000 readers,” over there, the way to “retire by the time you’re 32” over yonder, and “how to cure every known disease with this simple group of weird fruit from someplace you’ve never heard of (but you’ll certainly go find, and revel in the pictures of perfectly healthy inhabitants now),” naggling someplace at the back of your mind.

The insidious, distracting suck of the Internet has become seemingly inescapable. Calling us from our pockets, lurking behind work documents, it’s merely a click away. Studies have shown that each day we spend, on average, five and a half hours on digital media, and glance at our phones 221 times. -via connecting

Living this way isn’t healthy. It reduces your attention span, which in turn destroys your ability to get anything done, as well as destroying your mind. So we need to stop. “Squirrel” is funny, but you crash planes. “Shiny thing” is funny, but Continue reading

New Address

To make this blog a little easier to find, I’ve pointed rule11.us here as well. ntwrk.guru will continue to work, as well, but people seem to have a hard time remembering the url, so I added a second one.

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Slicing and Dicing Flooding Domains (1)

This week two different folks have asked me about when and where I would split up a flooding domain (IS-IS) or area (OSPF); I figured a question asked twice in one week is worth a blog post, so here we are…

Before I start on the technical reasons, I’m going to say something that might surprise long time readers: there is rarely any technical reason to split a single flooding domain into multiple flooding domains. That said, I’ll go through the technical reasons anyway.

There are really three things to think about when considering how a flooding domain is performing:

  • SPF run time
  • flooding frequency
  • LSDB size

design-files
Let’s look at the third issue first, the database size. This is theoretically an issue, but it’s really only an issue if you have a lot of nodes and routes. I can’t ever recall bumping up against this problem, but what if I did? I’d start by taking the transit links out of the database entirely—for instance, by configuring all the interfaces that face actual host devices as passive interfaces (which you should be doing anyway!), and configuring IS-IS to advertise just the passive interfaces. You can pull similar tricks in OSPF. Continue reading

Security ‘net: Internet of Things and iPhones edition

One of my college professors has suggested that the question of whether or not Apple should help the FBI break the encryption on the iPhone used by a terrorist is an ideal diagnostic question for your view of all things privacy. There are, of course, gray area answers, like “Apple should help the FBI break the encryption in this case, but not others.” The problem is, of course, that this isn’t the simple answer it might seem. First, there are motives behind the apparent motives. Many people see Apple as just “doing what’s right to save the world.” I don’t see it that way at all. Given I’m a bit cynical (who would have guessed), I see two motives from Apple’s point of view.

First, Apple is trying to protect a marketing stance. They’ve as much as admitted this in court documents and the implied threat of suing the U.S. Government for loss of revenue if they’re forced to build a version of their O/S that will allow the FBI to break the encryption. Just Security notes—

There are other interests at stake here too. Apple has a liberty interest in not being dragooned into writing forensic Continue reading

Why you should care about complexity

If you look across a wide array of networking problems, you will see what is an apparently wide array of dissimilar and unrelated problems engineers deal with on a daily basis. For instance—

  • Should I split this flooding domain into multiple parts? If so, where should I divide it?
  • Which routing protocol should I use on this network topology, and to solve this set of problems?
  • How should I configure the Quality of Service parameters on this network?
  • Should I use MPLS on my data center fabric, or straight IP?

Over my years as a network engineer, I’ve always treated these as separate sorts of problems, each with their own tradeoffs, concepts, and models. In fact, I’ve been a kindof “collector of models” over the years, trying to find different models to address each situation. In the Art of Network Architecture, there’s an entire chapter on the models Denise and I have run in to over the years, where they seem to be useful, and where they seem to be limited. complexity-model

But keeping all of these models in my head didn’t help me generalize the problems I faced in building and troubleshooting networks. For instance, in the flooding domain instance Continue reading

Security ‘net: Security by obscurity

This week I have two major themes to discuss on the topic of security, and one interesting bit of research. Let’s start with some further thoughts on security by obscurity.

First: Obscurity isn’t security

I’ve heard this at least a thousand times in my life as a network engineer, generally stated just about the time someone says, “well, we could hide this server…” Reality, of course, is far different; I still put curtains on my house even though they don’t increase the amount of time it takes a thief to break in. Whether or not we want to believe it, obscurity does play a positive role in security.

But there are two places where obscurity is a bad thing in the world of security. The first is the original reference of this common saying: algorithms and implementations. Hiding how you encrypt things doesn’t improve security; in fact, it decreases the overall security of the system. The second place? Communication between companies and security professionals about the types, frequency, and methods of attack. Imagine, for a moment, that you were commanding a unit on a battlefield. You hear the sounds of combat in the distance. Realizing a unit in your army is Continue reading