Aaron's Worthless Words

Sign in Subscribe

Latest

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

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,

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,

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

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

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

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