This page will contain some useful links to some projects and things I enjoy. I hope you can find something interesting.
This list contains mostly open soruce/free software projects.
GNU/Linux
The Linux Command Line: A solid book for learning the command line in GNU/Linux distributions. You can download the digital version of the book for free.
Qubes OS: A distribution that aims to provide security through isolation.
Tails: A privacy- and anonymity focused distribution that implements Tor and runs as a live distribution from a USB stick, DVD or similar.
Free Software Projects
The KDE Project: A free software project/community. The community is probably best known for developing the Plasma Desktop and KDE Frameworks.
Nextcloud: A platform for hosting and sharing your data. You can extend the functionality a lot by simply installing apps.
Syncthing: Peer-to-peer file synchronization. A decentralized alternative to proprietary cloud services.
Tor Project: Anonymity online. Defend yourself against tracking and surveillance. Circumvent censorship.
Mastodon: A decentralized social network. A microblogging platform.
Information Security and Hacking
Root Me: Hacking and Information Security learning platform.
Web Security Academy: Free, online web security training from the creators of Burp Suite.
Awesome Hacking: A collection of various awesome lists for hackers, pentesters and security researchers. So a list of list of interesting stuff.
Digital Privacy
Privacy Tools: Provides knowledge and tools to protect your privacy against global mass surveillance.
PRISM Break: Find privacy and security-aware alternatives to proprietary software.
Signal: A cross-platform end-to-end-encrypted messaging application. Signal can be used for chatting one-to-one, but also to have group conversations, for sending files and have video conversations.
Programming
Real Python: Python tutorials.
ZetCode: Tutorials for programmers.
Edabit: Learn to code with interactive challenges.
System Administration
Awesome Sysadmin: A list of sysadmin resources.
Miscellaneous
tldr: Simplified man pages.
F-Droid: An Android app and an app repository. Find open source apps for your Android phone.