David Trebacz Blog

I was noticing that many of the Arpwatch notification messages coming back were marked "unknown" for the manufacturer name in the MAC address lookup. I looked at the date of the file in my Ubuntu file system and it was last updated in 2012. Arpwatch uses this file to determine the manufacturer name for a given MAC address prefix. I found a script at this blog post which looked quite promising. A few simple transformations of the file downloaded direct from IEEE, updates from the comments on the blogpost and it was ready to go. I added in the lines to copy the files to the correct locations in Ubuntu's implementation of Arpwatch. Here is the updated script: Here are the basic steps and commands to do it on a terminal session. 1.Create the script using nano (copy and paste the script above) into a file called update_mac_addresses and then run it. nano ~/update_mac_addresses.sh 2. Make it executable chmod +x ~/update_mac_addresses.sh 3. Execute the script. S...

I found a quick and easy way to setup a way to test network speed on my internal network using the linux command line tool netcat (or nc), I used this for node to node testing of my wireless network under a variety of conditions. It required no extra tools or software to be installed on my Ubuntu linux machines. It gives me transmit speeds I can understand and easily allows me to size the payload to the type of network I'm testing. Put the first machine in listening mode (this example machine 192.168.0.188): nc -lk 2112 >/dev/null Put the second machine in transmit mode to send packets to first machine 192.168.0.188: dd if=/dev/zero bs=16000 count=6250 | nc -v 192.168.0.188 2112 The first part of the command tells the machine to copy 100 MB of data from /dev/zero in 16 KB blocks. The part after the pipe tells it to send that to the first machine (192.168.0.188) over port 2112. The output for this test on the second machine returns: Connection to 192.168.0.188 2112...

I had the main system drive on my 5 year old Kubuntu machine start having read errors in the syslog reported by logcheck. I had the system up and running straight for those 5 years and it was likely nearing the drives lifetime. I didn't want to have to rebuild the system from scratch, since it had served me well -just wanted to get a little more reliable disk drive in place (with a minimal amount of hassle). The drive I was replacing was a  250GB 7200 rpm SATA drive. I had an extra 500GB 7200 rpm Western Digital Black drive that had been a warranty repair. It had been gently used in a machine that needed more space. It was a perfect donor for the Kubuntu machine. It was currently mounted in a Rosewill USB external hard drive enclosure ( http://www.amazon.com/gp/product/B005KGNXTE/ ) . Here's an example of the errors in the syslog: ata5: EH in SWNCQ mode,QC:qc_active 0x1000 sactive 0x1000 ata5: SWNCQ:qc_active 0x1000 defer_bi...

This is the second part of the article about selecting, unboxing, and reviewing a Davis USB data logger (6510USB) and Vantage Pro2 Weather Envoy (6316) ( Part one of the review is here ). Vantage Vue Wireless ISS (Integrated Sensor Suite)  - 6357 Vantage Pro2 Weather Envoy - 6316  USB data logger with WeatherLink software - 6510USB In this part of the review we look at items 2 and 3 of the  system   Both of these units can work with other sensors, but the ISS  wireless  sensors met my needs. It also allows me to move the sensor  assembly  around as I find the perfect location for it. USB 2.0 datalogger and WeatherLink software box - front USB 2.0 datalogger and WeatherLink software box - back     Software manual, DVD, USB data logger, and 8 foot USB extension cable Very happy with the design of the USB logger and the USB extension cable qualit...

I decided to take the plunge and buy a Davis Vantage VUE weather station for my house. I wanted a quality unit that I wouldn't have to mess around with that reported reliable results. I also didn't want to pay a fortune for what is really a hobby. I planned this to be the perfect compliment to the McHenry Illinois radar weather that shows on my family website. ISS Sensors (big brown box - back), Weather Envoy (white box - left), and USB datalogger and software After talking with application specialist at Davis Instruments  I came to the conclusion that to meet my needs I needed: Vantage Vue Wireless ISS (Integrated Sensor Suite)  -6357 Vantage Pro2 Weather Envoy    - 6316  USB data logger with WeatherLink software  - 6510USB For me this made sense, since I wanted: To measure a variety of  outside  parameters Publish frequent measurements to the web (always available anywher...

A few months ago in another blog post I had a 1TB drive fail in my Ubuntu 12.10 linux mirror array ( http://blog.trebacz.com/2012/04/replacing-failing-drive-in-linux-raid-1.html ) . I decided to replace it with a 2TB drive to have room for further expansion. Using unequal drive sizes allows me to stagger my drive replacements I just ran out of disk space on the 1 TB partition, so I purchased a new 3TB drive. I really on need 2TB, but the Seagate 3TB drive was just to good of a price to pass up from Amazon. This is the second part of the story about adding a 3TB drive to my existing mirror and the challenges that I ran into. The whole process is just a few (11) steps 1. I checked the array to make sure everything was fine before starting. sudo mdadm --detail /dev/md0 /dev/md0:         Version : 0.90   Creation Time : Fri Mar 11 22:53:54 2011      Raid Level : raid1      Array Size : 976759936 (931.51 GiB 1000.20 GB) ...