Posts

Auditing Your Gear with Nipper

·2 min read

Let’s talk [tag]audit[/tag]ing for a bit. It’s important to have an outside person look over your [tag]configuration[/tag]s every so often to be sure you didn’t do something stupid, …

CBAC -- Context-based ACLs

·3 min read

Let’s set up a scenario. You have a single [tag]router[/tag] that terminates your T1 to the Internet for your company. You serve your own website and email, but you’d like to be as secure …

Services on an IOS Device

·2 min read

Have you even looked at the first few lines of your [tag]Cisco[/tag] [tag]switch[/tag] or [tag]router[/tag] [tag]config[/tag] and wondered what those “service” lines were? Yeah, me, too, …

Free and Awesome Network Tools

·3 min read

We all have limited budgets these days. Long gone are the days of unlimited resources and uncontrollable expansion of the network, so it’s important that any network dude or dudette pay …

A Simple BGP Lab with Dynamips/Dynagen

·4 min read

I assume you take every word I say to heart and that you’ve been using Dynamips/Dynagen for a few days now, right? Good. That’s a start, but let’s break down a simple lab to make …

Dynamips and Dynagen

·2 min read

I’ve run across articles for these apps a thousand times, so I thought I’d get in on the action. Dynamips and dynagen are a pair of apps that make simulating Cisco routers very easy. I use …

Monitoring the CSM with SNMP

·2 min read

I had an article a few weeks ago about the Cisco CSM, which is a load-balancer module for the 6500 series switches. This thing is a pretty good device, but monitoring the connections to each VIP and …

Object Tracking and HSRP

·3 min read

We’ve done some tracking with HSRP in other articles, but there are lots and lots of ways to use object tracking on an HSRP device. In our example network, we tracked the interface, and, if it …

Intro to Policy Routing

·3 min read

I like [tag]layer-3[/tag] [tag]switch[/tag]es. They give some great flexibility and bang-for-the buck, but most people overlook one issue with these things that can cause security problems. Most …