Desra Blog

As part of my home automation configuration, I wanted to figure out how to control my soundbar. Seems it's not documented, there isn't an API, but there is an Android App.  So I installed Genymotion, set the nic to be bridged and used wireshark to sniff what the app was doing.  I saw udp packets for each key, so copied the data, and used it like this.... Mute: 080312002a0808011204081a1002 followed by 080312002a0808011204081a1001  Vol down: 080312002a080801120408191002 then 080312002a080801120408191001 Vol up: 080312002a080801120408181002 then 080312002a080801120408181001 Power off: 080312002a080801120408011002 then 080312002a080801120408011001  switching inputs (optical/bluetooth/home):  080312002a0808011204084d1002 then 080312002a0808011204084d1001 So, to send this udp data to a sound bar at 1.2.3.4 address  echo "080312002a080801120408011002" | xxd -r -p > /dev/udp/1.2.3.4/9741  netcat seemed quite...

I Recently tried to use a webcam on the internet and it was unusable because too many people were using it. Taking a peek, it was clear it was simple jpgs being refreshed by client side JS , using the built in webui in the camera itself, the hardware just couldn't handle too many users. So I setup some urls and cloudfront to cache, and then an nginx proxy which would do the right thing with headers to make the images cache friendly.  Then reached out to the webmaster and talked them through what to do Next step is to consider changing the client JS to not just increment a number in the url, which is ignored by the CDN, but maybe find some other way to cache to you get better than one frame a second. server { listen  8888; access_log      /var/log/nginx/cam1.access.log; error_log       /var/log/nginx/cam1.error.log; server_name cam1.test.com; location / {     add_header Pragma public;     add_header Cach...

I thought I'd try alexa, and so it began .... Alexa (unlike google home) talks over your LAN to philips HUE devices, so you can simply setup a fake hue bridge to interface with alexa.  this is much easier than the official lambda foo you have to do in aws. I also had  domoticz setup, tracking my solar usage, electrical usage, and Nest data.  So, using habridge I ended up connecting habridge to domoticz, but will probably remove that integration, and just do habridge direct to my scripts. in domoticz I setup virtual switches that ran scripts, so habridge saw these switches and presented them like hue lights to alexa, so I can say things like 'alexa turn on sky tv' , or 'alexa turn on netflix' My two interesting problems were 1) how to turn on my tv, as it doesn't have WOL, and 2) how to handle CCTV (not really alexa related) My tv is an LG lm660t , which doesn't have WOL, so looked at solutions to use infra red to turn it on, but it all felt pr...

I have been doing some work in GCP recently, both appengine , and GCE.  We wanted to make sure all our instances were on private ips and only the LBs had internet ips. This gave us the problem of how to allow our instances reach the internet for updates or for api calls outside. In AWS you had a NAT gateway, but in GCP this doesn't exist. So I set about looking at the easiest way to do NAT from a private IP subnet to a Public address.  I am very familiar with m0n0wall and t1n1wall and a tiny bit with pfsense and less with opnsense. The tl;dr is that all these distributions ship an image which within the distribution there is a disk image.  Taking this internal image, renaming it and re-compressing it is all you need to do to get it working in GCE. you can configure it via the serial port using these instructions  There are guides out there around doing things with Linux and stuff, but you can skip that step. I took the latest version ...

For years I used --header "host: foo.bar" to make curl do the right thing when testing. Turns out there is a better way curl -svo /dev/null https://www.foo.bar --resolve www.foo.bar:443:127.0.0.1