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Tellstick ZNet Lite V2 teardown/reverse engineering

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Tellstick ZNet Lite V2 teardown/reverse engineering

(In english if someone outside of sweden finds this post usefull)

So I'm getting into trying to automate my home a bit with home assistant, and happend to stumble apon a second hand tellstick, which sounded good with booth 433Mhz and z-wave support.
It seems like the local api for home assistant by telldus has been depricated so you now have to use their cloud service to coontrol things.
So I thought i migth do a teardown and a bit of reverse engineering to se if its hackable in any way.

the inside of the Tellstick ZNet Lite V2:

The board part:

There is a debug 3 pin "debug" port next to the z-vawe module that is a TTL 115200 8N1 serial port staright into the tellstick openwrt console without password.

there is a python firmware update script cyclic running with a 86400 second interval
also a python tellstick-znet script
dropbear as ssh-server
udhcp for dhcp
ntpd for time
msdns for bonjour edtection.

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a bit of digging in the pythonscripts gave the firmware URL for telldus:
http://fw.telldus.com/versions.xml
http://fw.telldus.com/tellstick-znet-lite-v2/tellstick-znet-l...

it seems the python script tellstick-znet.py is the telldus client

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all the python files regarding telldus are bytecompiled .pyc files, possible to decompile with uncompyle6 though.

ports listened to on the tellstick:

root@OpenWrt:/# netstat -nap
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 1743/dropbear
tcp 0 0 10.0.2.22:59759 16.170.51.134:45000 ESTABLISHED 995/python
tcp 0 0 :::80 :::* LISTEN 995/python
tcp 0 0 :::22 :::* LISTEN 1743/dropbear
tcp 0 0 ::ffff:10.0.3.22:80 ::ffff:10.0.2.37:58554 ESTABLISHED 995/python
udp 0 0 0.0.0.0:42314 0.0.0.0:* 995/python
udp 0 0 0.0.0.0:30303 0.0.0.0:* 995/python
udp 0 0 0.0.0.0:56282 0.0.0.0:* 984/mdnsd
udp 0 0 0.0.0.0:5353 0.0.0.0:* 984/mdnsd
udp 0 0 :::546 :::* 1651/odhcp6c
udp 0 0 :::59699 :::* 984/mdnsd
udp 0 0 :::5353 :::* 984/mdnsd
raw 0 0 ::%1:58 ::%4438220:* 58 1651/odhcp6c
raw 0 0 ::%1:58 ::%4438220:* 58 913/odhcpd
raw 0 0 ::%1:58 ::%4438220:* 58 913/odhcpd

killing dropbear and starting it with
/usr/sbin/dropbear -F -P /var/run/dropbear.1.pid -p
instead makes login in as root possible with:
ssh -oPubkeyAcceptedAlgorithms=+ssh-rsa -oHostkeyAlgorithms=+ssh-rsa root@<tellstick ip-adress>

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