All posts by danman

$2 USB crypto token for use with GPG and SSH

If you are interrested in security devices this post may be for you. Recently I’ve found a software which makes a GPG security device out of a STM32. It’s called Gnuk. You just need a compatible board, programmer, flash the firmware and you are ready to go. I was just hoping to find some cheap device to flash to play with it.

Continue reading $2 USB crypto token for use with GPG and SSH

New version of Lenkeng HDMI over IP extender – LKV373A (Update 20. oct 2017)

Last week I’ve got the new version of Lenkeng HDMI extender – LKV373A. This version states incompatibility with previous version and usage of new HDbitT protocol so I was wondering what did Chinese engineers invent this time.

This blog is a log of my findings as they went through time. If you want a short review of the device watch this video from OpenTechLab (thank you!):

If you want to know more, just read the blog. Continue reading New version of Lenkeng HDMI over IP extender – LKV373A (Update 20. oct 2017)

Black thursday

Hi all!

Yesterday I suffered a great loss. All my data from this server went away… Unfortunately, I didn’t have recent full-backup of my blog so I needed to recreate some posts from WayBackMachine. That’s why most of pictures in posts from 2016 and 2017 is missing. Sorry for that. If you are interested in some exact pictures contact me, I can try to find them in my files.

I wish you more luck with your backups.


Multicast over “stupid” networks

IP multicast is an interesting technology. It’s main purpose is to
save network bandwidth as much as possible – traffic is sent to hosts
which asked for it only (as opposed to broadcast). On the other
side, you need smarter (manageable) switches and separate and
non-trivial configuration on both routers and switches. Even more
complicated it is when you try to make it work over VPN. Continue reading Multicast over “stupid” networks

Primitive webcam server using inetd and fswebcam

Hi all!

This weekend I was thinking how to make my webcam connected to
OrangePI send a picture “on demand”. There are daemons (e.g. motion or
webcam-mjpg) which do this but they capture images even when you are not
watching and I wanted to avoid this. There are also projects (fswebcam)
which are able to take single picture, save it to disk and end. I just
needed to run it after http request and send back the image. Installing
full webserver with some kind of interpreter (php, lua,…) seemed to me
like an overkill. So I came to an idea to use inetd.

And this is how I did.

Continue reading Primitive webcam server using inetd and fswebcam

Yet another IoT thermostat

Hi all,

this post will be about my homemade IoT thermostat.  The goal was to not install any cables (because I live in a rented flat), to go really cheap and to be able to set the temperature from anywhere. I’ll also give you some tips you should think about when building your own. Let’s get started.

Continue reading Yet another IoT thermostat