Monthly Archives: October 2015

Raspberry Pi 2, Raspbian Jessie and WiFi vs. Ethernet at boot-time

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I just installed Raspbian Jessie on my new Raspberry Pi 2. I’m using an Edimax EW-7811Un USB WiFi-adapter as a primary network device which I want to configure cleanly within my dis
tribution. Cleanly, in the sense of changing as little as possible the system’s configuration-files and scripts.

Raspberry Pi 2Of course I found several nice tutorials (1 2 3) which indeed helped me to figure how to do it properly
and gave me a good start (especially for wpa_supplicant.conf, which I won’t detail here) . However, the original content of the config-files mentioned there, wasn’t matching with what I found on my installation. Maybe it is because Jessie is still quite new as of writing this.

Starting with the /etc/network/interfaces-file. It mentions eth0 (the wired ethernet port) and two wlan-devices and it says they are all configured manual.

auto lo
iface lo inet loopback

iface eth0 inet manual

iface wlan0 inet manual
    wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf

iface wlan1 inet manual
    wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf

Manual in this context means that the ifplugd takes over the network configuration. Ifplugd detects a physical connection and launches a dhcp-client to complete the interface-configuration. As of writing this, it does not properly take care of wlan-devices, however this it is how ifplugd is configured (from /etc/default/ifplugd).

INTERFACES="auto"
HOTPLUG_INTERFACES="all"
ARGS="-q -f -u0 -d10 -w -I"
SUSPEND_ACTION="stop"

My RPI2 will be used mainly via WiFi, but for debugging reasons I might plug the wire. Hence I’d like the system to always (try to) configure the WiFi-device and optionally the wired if a cable is plugged. To achieve this, here is what I did.

First I changed the way wlan0 is configured in interfaces, telling it to automatically be configured when the networking-service is started (at boot-time):

auto wlan0
allow-hotplug wlan0
iface wlan0 inet dhcp
    wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf

Then I told ifplugd to no more using all devices but only eth0. I ran:

sudo dpkg-reconfigure ifplugd

And during the follow dialog asking me for “static interfaces to be watched by ifplugd’ I replaced auto by eth0. This makes /etc/default/ifplugd look as follows:

INTERFACES="eth0"
HOTPLUG_INTERFACES="all"
ARGS="-q -f -u0 -d10 -w -I"
SUSPEND_ACTION="stop"

This does exactly what I want with very few changes to the system’s files, thus clean.

UPDATE 30/10/2015:

I just did an apt-get update of my jessie installation and noticed that upstream has changed the interface-file. It now contains the allow-hotplug-lines I added to my interfaces. However, this does not change anything regarded the problematic I had on my system.

A tableau by “Jean Eve” or is it not?

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In March 2015 I bought this tableau from a private seller, a very nice person.

Jean Eve: Stein am Rhein, Switzerland

It is signed and was thus attributed to ‘Jean Eve’ by the seller. It was told to the seller, when he acquired it, that it shows a town in the Val D’Oise département in France named La Roche Guyon.

I have seen (before and since this acquisition) quite some pictures painted by Jean Eve. This one seemed quite different. To my amateur eyes this is basically due to the use of much more colors in comparison to other pictures. Whereas the straight lines and the blurry trees/valleys are quite resembling.

The day after having received the tableau, I had the idea to see how this place looks today. No problem, I thought, with today’s technology: Google Maps and Google StreetView will bring you anywhere instantly.

The mentioned town is located on the Seine-river. When looking it up on a map however, I saw there is no bridge. Over time bridges can disappear, especially in places in France under German occupation during World War II and this picture could well be before that date. However, StreetView was even more conclusive: there is no slope in this town or at least not such a steep one. And no castle or fortress in the upper part.

My conclusion: this cannot be the right place. Maybe it is another nearby town or village. I started to look where there are bridges not far away. I found one and looking at the bridge with StreetView I realized the Seine river is much larger than the one on the tableau. Conclusion: this is not at all the right place.

Switzerland?

To find out more I had to change my strategy and continue with the help of things visible on the tableau. I started with concentrating on the name of the hotel which is written with red ink on the biggest building close to the bridge. I was able to read the word “Hotel” quite easily, but the rest was much harder to decipher.

I started to read letter by letter: Hotel ‘B n e i t e t s’ was my first attempt, followed  ‘B y b u e r o l e t s’ . Using Google’s spell-correction I hoped to find miraculously the right name. It didn’t. And the more I changed the letters, the less the word made sense. The ‘n’ could have been a ‘u’. The two ‘t’s could be ‘l’s and ‘f’s. What is a ‘tefs’?

Then I had the idea to magnify the inscription with my camera taking a macro-picture. This was the key.

Jean Eve: Stein Am Rhein, Hotel Rheinfels

I now read B r e i n f e l s. Breinfels. In the meantime, due to Google’s geo-localisation-based suggestions I switched to duckduckgo.com and it corrected “hotel breinfels” to “Hotel Rheinfels”. Just looking at the first pictures it became clear: this is it. Hotel Rheinfels in Stein am Rhein in Switzerland. And not in France. First image was this page.

To be sure, I clicked on other links, among it a blog which was talking about Stein am Rhein and Hotel Rheinfels with lots of pictures one of it the fortress (Hohenklingen) up the hill. The silhouette of it was exactly the one in the tableau. Now I was sure about the place.

OLYMPUS DIGITAL CAMERA

Image copyright: TravelsForFun – the Snyder family – see their blog: https://travelsforfun.wordpress.com/

Is the tableau authentic?

While at first I just wanted to see how the depicted place looks nowadays, having found out that the original description of the tableau is not correct, I need to make sure that the rest is authentic. Basically, this means to answer the following questions:

  1. When was it painted?
  2. Can the tableau authentically associated with Jean Eve?

These two questions are actually related. When I have some time, I will dig into it.