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Isolated Guest Network with a Raspberry Pi

Recently I was unsatisfied with the possibilities my FritzBox router gave me concerning the guest network. At first glance, all was fine - the box allowed me to set one port as "guest network" which was isolated from the rest of my LAN. But then I wanted to set a Pi-Hole as DNS server. It proved difficult to combine both and was relatively slow at the end. So I got a Raspberry Pi 4 Model B with the minimum RAM configuration of 2 GB to manage my guest network. It's rather cheap but you can do a lot of things with it.

The RasPi comes with built-in Wi-Fi but I wanted to use my VLAN-capable access point infrastructure which I already had in place, so I also bought a USB network card to give the RasPi a second ethernet port. Using a spare SD card I had laying around I set it up with a fixed IP address in my LAN, connected the external network card to the VLAN which was to become the guest network and also configured this with a fixed IP address.

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Heavy (Log) Rotation

Sometimes I am at the point where there's too much log output, but I don't want to send everything to /dev/null because of some rare bug. The easiest way I know to retain some fixed amount of logs is to use rotatelogs from Apache HTTPD - e.g. in the following fashion:

some_command 2>&1 | rotatelogs -n 5 /var/log/some_command.log 100M

Hope to help somebody with this (perhaps the future me)...

Use Canon CanoScan 9000F Mark II to digitize slides and prints on Linux

Some time ago I collected some boxes of slides from my parents and parents-in-law. The pictures were taken in the 70s and 80s and it would be a shame to disregard them, so I set out to create a workflow to digitize them. I bought a CanoScan 9000F Mark II because the Linux support is good - this piece of technology can scan with 4800 dpi which should be sufficient even for advanced use. I confined myself to 1200 dpi which gave me pictures of 1650 x 1080 pixels. The process took 35 seconds for 4 pictures (scanned in one go).

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Certificates and the JVM

The recent events revealed that the internet is not a very safe place. If you don't encrypt your data, it is likely to be analyzed by third parties like intelligence services. So you start to encrypt everything because you care for the safety your customers data. You managed to get it done without extra budget because you use a self-signed certificate - but oh, what is this? A nasty ValidatorException saying "PKIX path building failed". What now?

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