The fourth part for the Computer Lab Box is to establish a connection between the targets and the home network. With this connection it is possible to connect the targets via ssh over ethernet and to update the target over the internet. I want to have a static ip-address which is provided by the dhcp-server in the main computer (Raspi 3).
First, I thought to implement a bridge into the Raspi, but unfortunately the Raspi does not support WDS. The other possibility is to build a NAT.
I wrote a script which is placed in /etc/rc.local that makes a NAT in the direction to the home network and a DNAT in the direction to the subnet of the targets. The targets are connected with the main computer via an ethernet switch. The script and all the settings can be found in the Routing.zip.
Here I must thank my colleagues, Christoph Plattner and Martin Neuditschko, for helping with this issue.
ad Part 1: I had troubles with the power Raspi 3. I thought that max. 2.4 A of the OTB charging adapter USB would be enough for the Raspi. But the power LED of the Raspi started to blink from time to time and I also lost sometimes the ssh connection.
I could not find any USB charger with more than one port that gives 3 A. If I can not keep the system elegant and small, then at least I will try to keep the Lab Box simple. Every “high” power consumer will get its own power supply. All other devices will be connected to the OTB charging adapter.