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Aaron's Worthless Words

It's possible that someone somewhere needs to know this.

2007-10-02

Getting Started with the Cisco CSM

Cisco’s Content Switching Module (CSM) is an application accelerator. Or is it an application networking service module? I hate those fancy buzzwords — it’s a load balancer. It’s a module for the 6500 series switches that lets you load balance services in any VLAN and can also be set up for high-availability. I could go […]

2007-09-27

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 receive the ICMP packet and drop it per the […]

2007-09-24

Filtering Outbound Traffic

I’ve seen a thousand [tag]firewalls[/tag] in my time, and nearly all of them are poorly configured. The biggest culprit? No [tag]outbound[/tag] [tag]filtering[/tag]. I guess a lot of people think that firewalls are there to protect the network from the Internet, but that’s only part of it. The firewall is to protect every segment from every […]

2007-09-23

HSRP Interface Tracking

Remember the article on router-on-a-stick? And the one on HSRP? Let’s add to that example network, shall we? Let’s make those routers into edge routers so they connect your internal network to the Internet with some size circuit. Let’s just say they each terminate DS3s to different providers. Here’s our network now (I’m experimenting with […]

2007-09-16

SNMP v3 is Easy!

I finally got around to looking into [tag]SNMP[/tag] v3 and was shocked at how easy it actually is. When I first looked up info on it so many moons ago, I saw table after tables of views and privilege levels and thought I would have to put in a billion hours getting it customized. I […]

2007-09-11

Ideas That Seems Good At the Time

When I started in IT, I tried to get my gear as standardized as possible to impress everyone. I worked at it and worked at it until I realized that there were a handful of things that sound good but just won’t work. If you’re just getting started in the field, you may not agree, […]

2007-09-04

Setting Up SSH on IOS Devices

By default, most Cisco [tag]IOS[/tag] devices come configured to be accessed via telnet. This is probably fine for your house, but I really cringe when I run across corporate networks that use [tag]telnet[/tag] to access the devices. Telnet is old and out-dated and can be very dangerous. It’s in plain-text, which means that anyone who […]

2007-08-30

When Does a Tab Save You Money?

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 everyone […]

2007-08-29

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, people […]

2007-08-28

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 in […]