Aaron's Worthless Words

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linux

A Simple BGP Lab with Dynamips/Dynagen

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 sure everyone’s on the same page. I run my labs

Finding Hosts on Layer 2

Most firewalls should block [tag]ICMP[/tag] requests to them, so how do you know that your router or server has layer-2 connectivity to one? It’s pretty elementary, actually, but I’ve found that not a lot of people know this trick. If you ping the firewall, it will

Using a Linux Box as a File Server

Ever heard of Samba? You should. Samba is an open-source project “that provides seamless file and print services to SMB/CIFS clients.” That’s from the project’s website, but what the hell does it mean? In a nutshell, it’s an open-source application that lets non-Windows machines share files

Port Knocking

A few months ago, a friend of mine told me about the concept of port knocking, where you send packets to a server on certain ports to authenticate access to the box. A daemon running on your server detects the sequence of packets that you send and runs a script

Using an Old Server as a Home Firewall

You can use an old PC as a firewall at home (and at work, I guess). It’s not that hard to do if you have a basic knowledge of Linux, DHCP, and IPtables, but that may be saying a lot. Why would anyone want to do this, though? If

The Principle of Least Privilege

The Principle of Least Privilege says that users or applications should only have access to the what it needs to access and that access should be as limited as possible. This idea can be applied to any number of things, but it is a very important topic when talking about