I’ve bought a Koubachi Sensor Pro 2 in order to check the temperatures for the turtles of my wife. It’s a very interesting device because it supports outdoor conditions.

koubachi

It looks pretty cool and it’s a swiss product.

But the pain begins with the connection with your Wifi network. It seems that this product has many bugs with the 802.11 standard. It supports WEP, WPA and WPA2 but with some equipments it’s just impossible to connect, or it returns a stupid DHCP error.

Here my experiences…

I’ve installed OpenWrt on my D-link DIR-825 router because the original firmware is just a crap. Like for Netgear R6250 routers for example (unless that OpenWrt is not still supported).

I follow the Koubachi procedure under Linux and my laptop, but it was impossible to connect to the sensor (ad-hoc mode, press 3 seconds the button, then the LED becomes orange, connect to the sensor). Urf? Okay, I’ve tried with Windows 8.1, same problem… I change of computer, oh.. I can connect to the sensor. Cool but why it was a problem with my laptop? Note that with an other laptop it’s impossible to connect to the sensor too.

Okay, I’m a lucky man because I’ve many computers at home and several Wifi networks.

Just one thing, avoid to use the application for Windows provided by Koubachi. It’s useless and it is not working better.

If you can connect to the ad-hoc network (koubachi_config), then you should be able to open a web page on http://127.29.0.1.

Cool, now you can enter the email of your Koubachi account (+ password) and to select the Wifi network (+ password). Then you try to apply your choices and… then your receive an error message because the sensor has not received an IP, then you should check your DHCP.

LOL, are you joking? All my computers (old and new) can receive an IP from my router, but the Koubachi sensor can not… WTF? I’ve spent a lot of time to find the problem. I’ve tried with an open network (no more WEP/WPA/WPA2), I’ve tried to change some settings in OpenWrt, I’ve tried with an other router (then it was working but this router is too far :-(, at least the sensor is working).

Okay, I’ve lost many hours with a product dedicated to lambda users. Maybe I’m a lambda user too or (I prefer this hypothesis) the Koubachi engineers just lack of skills.

The solution with my DIR-825 router and OpenWrt

There are two problems with the sensor. First problem, there is a strange error in the log of OpenWrt, something like that:

IEEE 802.11: associated (aid 3)
WPA: pairwise key handshake completed (RSN)
IEEE 802.11: deauthenticated due to local deauth request

Uhm… why this “deauth request” appears here? I don’t know… but something is broken with the sensor. Then the solution is to disable the WPA group rekey for this WLAN. Because I don’t want to change the WLAN settings for my other clients, I’ve created a second master (named “Sensors”) on the same antenna (thanks OpenWrt, because with the original firmware it’s just impossible to create two masters).

Something like:

config wifi-iface
        option device 'radio0'
        option mode 'ap'
        option ssid 'Sensors'
        option network 'wlan0'
        option key 'my_super_key'
        option wpa_group_rekey '0'
        option encryption 'psk2+ccmp'

It is important to have option wpa_group_rekey ‘0’. You should force AES too (over TKIP) because it seems that the sensor doesn’t like TKIP very much.

The second problem is about the DHCP. The dnsmasq daemon tries to handle the DHCP request, but the sensor does nothing… I’ve just tried an option by despair, and it was the right thing to do.

In the config-iface settings, you should add this line too:

        option wmm '0'

Hey, the Koubachi sensor replies to the DHCP daemon.

Ouf, now it works :o)

By Koubachi

It seems that the Koubachi engineers are aware that the Wifi support of they sensor is crappy because there is a list of routers which are not supported.

If your router is in the list, you should look if OpenWrt supports yours. Then you should change the firmware for OpenWrt. Even without Koubachi sensors you should use OpenWrt when possible.