ODROID boards are perfect for building custom Linux based firewall solutions. A friend of mine recently asked me for instructions on how to do that. So here they are.

There are many articles on the internet on how to generate a TLS certficate with the Subject Alternative Name (SAN) extension, but most of them won't work anymore. So here is another one, which hopefully works.

The El Torito Bootable CD Specification was introduced in the 90's to make it possible to boot a system from a CD. This specification is used till today for bootable ISO images. There are different ways to embed disk images into El Torito ISO images. One way is called hard disk emulation. With this the bootable disk image comes with a DOS/MBR boot record and can be booted by the BIOS/UEFI directly. Unfortunately if you want to boot such an ISO from an USB stick, that won't work out of the box, you need to extract the disk image from the ISO first. This article is about how you can do that easily under Linux.

Cheap bluetooth adapters often share the same bluetooth address (BD_ADDR). That is especially a problem if you want to use both at the same time with the same device. Fortunately one can change the address of a bluetooth adapter with the bdaddr command (delivered with recent versions of bluez-utils). This is a quick howto for recent versions of bluez.

Many Linux distributions will or have already switched over to Python 3 as default interpreter when running the python command. At the same time many people are still used to Python 2 and might not be aware of the changes that come with that switch. Especially string and byte handling is different from Python 2. This article is about some common pitfalls and how to prevent them with Python 3.