I was talking to some guys at work today about scalability and data efficiency, and an example came up that I had to think about for a second. One of the guys, a lead developer, started talking about the difference between 5 spaces and a tab. He said that the programming standard says that...
Monthly Archives: August 2007
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 and printers with Windows machines. In most cases,...
Make Your Own Ethernet Cables
If you need to buy an Ethernet cable, you’ll pay quite a premium for it at your local CompUSA or Circuit City. $22.99 for a 7′ Ethernet cable is terrible. For just a few dollars more, you can buy a 250′ roll of cable and make 35 of them yourself. You’ll need to invest...
Security for Unmanned Devices
I was talking to a coworker the other day about setting up his home network more securely. “No problem,” I said, and we started listing devices on his network to see what we needed to do. I was pretty surprised that he had so many things on his network. I mean, I was quite...
Running HSRP for Availability
In the article describing a router-on-a-stick, I mentioned that I would use two routers that run HSRP for availability, so I figured that I would write up a short post on what it is and how it works. HSRP (Hot Standby Router Protocol) is a Cisco-proprietary protocol for establishing two or more layer-3 devices...
Router-on-a-Stick
Ever heard of a router-on-a-stick? Go ahead and laugh…everyone does. It’s a funny name for a very serious topic, though. A router-on-a-stick is a network configuration that uses a single router interface as a gateway for more than one network segment. You literally take a single Ethernet interface, put it on multiple VLANs, and...
Common Cisco IOS Commands
Here’s a list of IOS commands that I use all the time that aren’t a part of the basics. I obviously use more than just these, and you do, too, but I hope there’s at least one eye-opener in there. show env all: Shows the environment status, including fan, power supplies, etc. Good for...
Separation of Function
Separation of function is another important security concept that people often overlook. It can mean that a single person is only responsible for one part of a process. Or it can mean that one server only does one function. Or it can mean that one network is used for servers of one type. Or...
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 (usually IPtables commands), waits...
Fallback IPtables
The hardest part of messing with firewall configs is knowing what is going to lock you out of the firewall itself. It doesn’t to me very often, but I’ve been doing firewalls for 10 years now. I was thinking about my own IPtables implementation at home and realized that I do most of my...
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