Introduction There was an advent calendar on http://xmas.rip/ that had a little network riddle every day: The riddles are very fun. I solved all except for the one on day 22. Here are my solutions. 1/TCP Day 1: Connect to port 1 using ncat and the -C option to send proper CRLF linebreaks. Sadly, the service does not support the HELP command that would output all services: $ ncat -C xmas.rip 1 HELP -Service name not found Ncat: Broken pipe. Start the wishlist service using the wishlist command: ...

Introduction WireGuard is a relatively new open-source software for creating VPN tunnels on the IP layer using state of the art cryptography. I attended a self-organized session by the creator and developer Jason Donenfeld at the 34c3 who explained how WireGuard works and how it can be used. I was quite impressed by it’s simplicity and gave it a try. It worked more or less out of the box. Now I created a more advanced setup for accessing my home network. ...

Introduction The RFC 4648 (The Base16, Base32, and Base64 Data Encodings) defines different methods to encode binary data. Every Unix like system has the tool base64 installed to encode and decode data using the base64 alphabet. This alphabet includes the characters A-Z, a-z, 0-9, +, / for the data and = for padding. The base16 encoding scheme, better known as hex encoding, uses the alphabet 0-9 and A-F. This encoding is case-insensitive. The GNU coreutils do not include a base16 tool. I searched for a hex encoding and decoding tool with the same functionality as base64 without success. That’s why I wrote a script so I can use it to hex encode and decode binary data. Basically, it’s a wrapper around some Perl code. ...

Introduction If you take a photo with your Jolla phone, the date and time is not saved in the EXIF data. I like to have these data stored in my pictures, so they can easy be renamed. I wrote a script to add the date and time to the EXIF data based on the timestamp on the filesystem. Script The script does the following: Add the EXIF timestamp according to the filesystem timestamp Renames the photo like YYYY-mm-dd_HH-MM-SS Rotates the photo correctly Here is the script: ...

Introduction This post describes an installation of Arch Linux with GPT (GUID partition table), LUKS (Linux Unified Key Setup) and LVM (Logical Volume Manager) with the basic graphical window manager i3. LVM is set up on top of LUKS. Systemd-boot is used as an EFI compatible boot manager. I wrote this post, so next time I don’t have to search all the information in the Arch Linux Wiki. For more details, consult the links in the reference section. ...