Technology Insights

How to Merge Multiple WLAN (IEEE 802.11) Captures into One File

I recently had a customer upload a WPA capture to our tools.question-defense.com server which failed immediately. This can happen from time to time and is for a variety of reasons Sometimes if captures does not contain all 4 eapol packets they will fail , and sometimes if a capture has lots of other wifi garbage in the .cap file it can confuse the cracking program. This last time was a new situation. After the fail I analyzed the cap file and determined that the essid was not present in the capture. This is absolutely crucial for the decrypting process. In this short article I will show how I determined the essid was not present and what I did about it.

Technology Insights

LM_Sensors on Cent OS 5.4: How To Get And Install The Coretemp Module

If you have been following my progress over the last few days you will know that after a complete rebuild of the tools server and a change of the operating system, I have been working hard to get all our temp monitoring back online. The server previously ran Gentoo Linux, which although is still my favorite distro, is just not suited for a production server environment.  So we decided to go with Cent OS which is a very well built distro aimed at running on production servers. My only complaint is that its kernel and some of its packages are a little bit out of date.  On the bright side, this has given us a few challenges to work through and more importantly some good articles to share.  So after getting my GPU temps going and graphing I turned my attention to the cpu. We are currently running a Intel i7 965 Extreme edition which I just put in last night. In the following article I will show how I eventually got lm_sensors and the coretemp module to work on Cent OS 5.4

Technology Insights

Graphing GPU Temps with Gnuplot on a server

If you have been keeping up with the development on our tools server you will know that we just did a big rebuild and I was looking for a way to monitor the GPU temperatures. Yesterday I wrote a article about how to get these temperatures on a linux server which does not have a X-server installed. Alex is currently writing some custom Cacti plugins to monitor temps but in the meantime I decided to figure out another way. I have never needed to use Gnuplot for anything and I figured this was as good a time as any to learn.

Technology Insights

Send A Text Message From A Shell To A User Logged Into A Linux Server

This topic is fairly known to most older system administrators however I doubt it is used very often anymore. If you happen to manage any servers where there are typically various people logged in and working on different items from the CLI then it can be useful to be able to send them messages. Using the write command you can send messages to users logged in on specific TTY port or by username. Below are a couple examples of how you would use the write command from a Linux shell.