How to use Arduino 1.0.6 under Mac OS X 10.10 Yosemite

Apple disabled java under newer Mac OS X versions. This is normally no big problem, because if you want to start a Java application, Mac OS X will inform you that you’ll need to install java. In case of Arduino, it requests Java SE 6 runtime:

Taken from
Taken from

I’ve decided to install Java manually with the packages provided by Oracle, because they are in a higher version and have less security holes. However, this will lead to problems as some Java applications which where build for Java 6/7 cannot start on Java 8 from Oracle.

I’ve tried it then with the most current Arduino Beta 1.5.8 which supports newer Java versions. While Arduino now starts, it cannot compile Arduino sketches. If you try the older Arduino 1.x versions, it will not start at all.

Only after installing Apples Java for OS X 2014-001 update, I could start Arduino 1.0.6 again and then compilation was also no problem anymore. If I check my java version with java -v  in a terminal, I’ll see that the system is using java 8 instead of the installed 6. So I think its safe to use. What do you guys say? Leave a comment if I missed something!

Sync Borderlands Prequel and Borderlands 2 savegames between Mac and PC

I really liked Borderlands 2. So much, that I played over 42 hours already :) This happened all on my gaming PC. With my new Macbook Pro and the availability of Borderlands for Mac, I intend to play it in LAN mode occasionally when I’m visiting friends who also play Borderlands. However, I was shocked when I started Steam on my Mac and did not see the savegames from my PC, although Steam’s Cloud Synchronisation was active.

Borderlands 2 Steam Cloud Sync

A short research showed that the developers of Borderlands had this feature deactivated, because they cannot guarantee that the correct patch versions are applied to all platforms to the same time. This could lead to possible corruption of the savegames and so they disabled Cloud Sync although it is activated by default:

Q: Will I be able to sync my game saves between the Windows PC, Mac, and Linux versions?

A: Yes, but with a caveat: characters and saved games will NOT sync between Windows PC, Mac, and Linux via Steam Cloud.  Since the Mac and Linux versions of Borderlands: The Pre-Sequel may frequently be in an out of sync with the Windows PC version, syncing game saves across platforms via Steam Cloud has been disabled.  This will ensure saved game data will not be lost or corrupt due to incompatible in-game content or other unforeseen reasons.  Users do have the option of transferring game saves via physical media (like a thumb drive) if they wish.


Nevertheless, a clever user on the steam forum created a nice tutorial. He intends to use Dropbox with NTFS and HFS+ symlinks to link the savegame folder to Dropbox. He suggests to use the mklink command this way:

What he did miss to tell you is that you’ll need an elevated command window with administrator rights. Just enter cmd on the Windows 8 start menu and select “Open as administrator” on the command prompt.

The next problem is the order of the folders. In his order, this will result in an error message stating that the link could not be created. However, if you look up the command on MSDN you’ll see that you must switch the order of the arguments. It is first the Link name (in your Dropbox folder) and then the Target (What do you want to link).

All other information in that forum is correct. You’ll need to link this numerical Id folder with your savegames to a Dropbox synced folder and do this also on the Mac. Be sure to create a backup before you create the links in case you overwrite your savegames. After that, it works. This will also work for Borderlands The Pre-Sequel!

Update OpenElec 4.2.1 to 5.0.0 on a Raspberry Pi

XBMC is no more, it was replaced by KODI. The OpenElec team updated its media center distribution to version 5.0.0 which includes KODI. So it was time to update my RaspberryPi and its really easy:

  1. Backup your current installation with the OpenElec Backup tool.
  2. Move your backup to a secure location. You can access the backup tar file via SMB from the backup share.
  3. Download the 5.0.0 release image for Raspberry Pi.
  4. Place the tar file in the update share of your OpenElec installation.
  5. Reboot your Raspberry Pi.
  6. It should be rebooting a few times.

After these steps you should be greeted with the new KODI logo.

Kodi start screen

And you’re done, its really easy as a Pi ;)

How to use client certificates with Synology VPN Server and OpenVPN

The holidays are near and I want to have access to my files on my Synology NAS, while I’m visiting my family. That’s why I’m showing you today how to configure the official Synology VPN server to use OpenVPN with client certificates instead of username/password.


1. Start with a custom root CA

First of all you need your own self-signed root CA. A useful tool is XCA but you can also do this from the terminal.

2. Create a certificate for your DiskStation

Create a new Certificate for your DiskStation. Be aware to use the assigned DNS name, otherwise your browser will complain when you try to connect to the web interface of the DiskStation.

3. Configure the DiskStation to use the server certificate

I’m using DSM 5. There’s a nice new Security setting in the system settings. You can define and upload a certificate there:

Import CertificateThe Private Key and Certificate fields are straight forward. However, the intermediate certificate is the tricky part I forgot. This is the certificate of your self signed root CA. Only with this additional certifacte the trust chain is complete.

4. Trusting the root CA

The next step depends on your computers OS. I’m using Mac OS where I can easily add the root CA certificate as an always trusted certificate.

5. Reload the web interface of your DiskStation

After you’ve set the certificate, the web interface should have been reloaded. Eventually you’ve been warned by your browser about a security issue (you did not trusted your root CA, therefore the web page was untrusted). After a reload and the instructions from step 4, this warning should go away. If you take a look at the certificate tab of the DiskStation’s security setting, you will see that your new server certificate is active.

6. Install the VPN Server

Install the VPN Server from Synology’s Package Center. Its configuration is done from the start menu.

7. Configure the VPN Server

Enable OpenVPN from the Settings of the VPN Server. For more details see Synology’s instructions.

8. Connect via SSH to your DiskStation

Disable user authentication on the DiskStation and enable the certificate based authentication (code taken from this wiki) in this file: /usr/syno/etc/packages/VPNCenter/openvpn/openvpn.conf


9. Configure your client

I’m only using iOS devices and Macs. Therefore this is again a little biased :) The installation of the clients for Mac and Windows is explained on Synology’s page. iOS is explained on this page (only in german but with screenshots). The initial configuration can be downloaded from the OpenVPN settings page from the DiskStation web interface. The extracted zip file contains the servers official certificates but needs to be modified to add support for the client certificates. Text is taken again from same wiki as above.


The DiffieHellmann Parameters (dh) can also be created with XCA. I would recommend 2048, since 4096 takes ages to generate.

10. Give it a try

Now you can test your VPN connection on your devices. It should not ask for a password, instead it should use the my.crt and my.key you’ve set in the configuration.

AVM Fritz!Box 7490 und AVM Fritz!WLAN Repeater 1750e

Vor gut zwei Monaten habe ich einen VDSL 50 Anschluss der Telekom beauftragt. Als Router habe ich dazu die AVM Fritz!Box 7490 gewählt. Sie ist momentan das Top Model und bietet 802.11ac WLAN an. Das superschnelle WLAN, als auch das angeblich bessere (im Vergleich zur 7390) DSL Modem, haben mich dann zum Kauf bewegt. Schließlich habe ich mit meinem neuen MacbookPro auch endlich ein Gerät, das diese Geschwindigkeit ausnutzen kann.

Hier mal ein paar Punkte, die mir aufgefallen sind und mir auch gut gefallen:

  • 802.11ac WLAN funktioniert tatsächlich wahnsinnig gut. Ich habe etwa 2 Wände zwischen meinem Schreibtisch und dem Router, trotzdem kann ich immer noch mit gut 800MBit funken.
  • Das DSL Modem funktioniert hervorragend und hat die Leitung maximal ausgereizt (50MBit down, 10MBit up).
  • Das neue Fritz!OS 6.20 hat Unterstützung für meine TP-Link TL-PA551 Powerline Adapter. Damit kann ich mir die eigentliche TP-Link Software sehr gut sparen.
  • Das WLAN Setup ist denkbar einfach. Spätestens, seitdem man auch QR Codes mit den Zugangsdaten direkt generiert bekommt.

Besonders begeistert war ich allerdings, als ich den AVM Fritz!WLAN Repeater 1750E als Bridge eingerichtet hatte. So wird das Büro mit WLAN sowohl über 2,4GHz als auch über 5GHz mit dem Router verbunden. Es wird immer automatisch die schnellste bzw. stabilste Verbindung verwendet. Gegenüber dem Powerline Adaptern war das sicher eine sinnvolle Entscheidung. Scheinbar gibt es zuviele Störungen im Stromnetz, so dass ich hier Powerline nicht sehr schnell benutzen kann. Damit konnte ich auch nicht die volle VDSL 50 Geschwindigkeit ausnutzen. Mit dem Repeater lief es allerdings wieder auf voller Geschwindigkeit.

Fritz!WLAN Repeater 1750E  & TP-Link551 Powerline Adapter

Wenngleich der Repeater im Moment auch schwer zu bekommen ist, so kann ich ihn durchaus immer wieder empfehlen! Die Einrichtung war spielend einfach (dank WPS Knopf) und die Performance ist einfach nur traumhaft.

Einziger Knackpunkt, den AVM aber auch in einer der nächsten Firmwareversionen hoffentlich fixen wird: Es ist keine feste IP Vergabe möglich für den Stick. Man kann ihn lediglich per DHCP auf eine IP setzen:

Die Kombination aus der Fritz!Box und dem Fritz!WLAN Repeater ist wirklich gut. Ich hätte theoretisch ja auch einen aktuellen AirportExpress wählen können, dann hätte ich allerdings vielleicht doch wieder Probleme mit irgendwelchen Besonderheiten oder Verschlüsselungen gehabt. Es gibt also nicht wirklich viel an der Box zu kritisieren. Sie erfüllt ihren Zweck, ist schnell und für mich absolut ausreichend (auch in Hinblick auf kommende DSL Generationen). Da ich sie auch als Telefonanlage mit DECT Telefon verwende, wäre eine verbesserte FAX Funktion noch nett. Der in der Weboberfläche eingebaute FAX Client kann nur Bilder verschicken, keine PDFs.