David Trebacz Blog

I'm still having issues with the Honeywell wifi thermostat (RTH9580WF) displaying "waiting for update" on when the wifi is routed through my proxy server, so I decided to do a deep dive into what the thermostat is doing when it's getting the weather updates. I also wanted to better understand how to trace traffic on my network. Here's what I learned about the thermostats weather updates system by tracing the communication between the thermostat and servers. Currently: Thermostat requests the current weather and 12 hour forecast from a server:  http://104.209.185.251 . This server appears to run code managed by Honeywell in Microsoft's Azure cloud. Every 15 minutes it makes two port 80 GET requests to the IP address: http://104.209.185.251/WeatherAPIProd/api/weather/current?appKey=b9db7a3d469892e8&language=en-us&locationKey=36691_PC  (return current weather for location) http://104.209.185.251//WeatherAPIProd/api/weather/forecasts/hourly/12hou...

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 decided to take the plunge and upgrade my Dell Optiplex 755 USFF music PC from Windows 7 to Windows 10. The idea of a free upgrade with smaller disk footprint and better security was just too good too pass up. The upgrade went pretty smoothly until about two weeks later. At first everything seemed to work wonderfully. Then I started to be unable to wake the Dell Optiplex without a reboot. There were also some weird chimes coming from the speakers when the computer was unable to be wakened. The hard drive was working, so it appeared the computer never actually made it to sleep mode. Especially annoying, since this PC provided our streaming music on our patio. I even went through a complete Windows 10 OS reinstall , to see if that would help. No avail. I tried turning hybrid sleep mode on or off. I applied a BIOS upgrade from Dell. I looked though the event logging and found nothing out of the ordinary. Currently, I have disable sleep altogether and resorted to mapping my sleep b...

We bought a new house in Fountain Hills, AZ. With the hot weather in the summer it just seemed to make sense. Being the science guy I really wanted to understand why all this pool chemistry stuff seemed so complicated. I'm a DIY guy and a scientist, so how hard can this stuff really be. The 4 main DIY tools to maintain my swimming pool chemistry and water clarity are: My friend Bill He's had pools in Arizona for many year, but not sure how to franchise his knowledge, so most of you can skip this one. Trouble Free Pools website http://www.troublefreepool.com  - great website with real information on pool chemistry and how simple it really is. I now effectively maintain my pool myself with Walmart bleach  (sidum hypochlorite and water), Muratic acid. When filling the pool I added  Cyanuric acid  as a Chlorine stabilizer and Borax as a buffer/mild anti algaecide. Now "knowing" my pool, It's a couple cups of bleach every morning and some acid on t...