Found and saved useful links

Linux tips and instructions

• Linux Upskill Challenge
• DebianAdmin (overall Debian manuals)
• Linux SysOps Handbook
• Bash scripting manual
• The Geeky Way: Linux
• Linux Package Management Comparison
• Linux Package Management Comparison [Arch Wiki]
• Ubuntu Package Management
• Deb repositories sources.list
• Apt cheat sheet
• AppImage on Linux
• Bash history management
• Job scheduling: cron and at
• Job scheduling: systemd-timers
• Unix Less Command
• Remove spaces from filenames
• Firewall: iptables basic rules
• Firewall: UFW
• Firewall: iptables logging
• Permanent blocking with fail2ban
• Cockpit System Monitoring + Nginx
• PAM-U2F Yubikey (local Linux account)
• Increasing partition without reboot (without LVM)
• [Arch Linux] Yubikey+LUKS
• [Debian] Yubikey+LUKS
• LUKS unlocking with FIDO2, TPM and PKCS#11

Other configuration/usage manuals

• Baszarek Wiki - Linux, software, scripting and configuration tips [PL]
• Git documentation (+ Pro Git book online)
• Darcs Version Control
• Use The Index, Luke - database guides
• Encypted backups for safe cloud storage [PL]
• File encryption with OpenSSL
• GPG Subkeys
• Offline master GPG key
• Import GPG keys from specified servers
• SSH keys randomart
• DrDuh's Great Yubikey Guide
• Decoding Base64 in command line
• Flexbox in CSS
• Extremal backward compatibility in websites
• Starting blog with HUGO
• Arpspoof basic usage
• PKCS#11 URI scheme
• OpenSSL CA/PKI guide
• SSL CRL reasons
• OpenSSL and ECC keys
• Opensc (Smart card tools)
• YubiKey [multiple] challenge-response configuration
• Nitrokey HSM first steps
• Nitrokey HSM + Smard Card Shell

Some online tools and resources

• Base64 encode/decode
• QR code generator [PL]
• GNU Packages Checker
• HTML colors
• Characters and symbols in CSS/HTML
• HUGO (website/blog generator)
• MKWS (simple site generation)
• Matrix Federation Tester
• Introduction to Gemini protocol

Privacy-related

• Dangerous Privacy/Security Myths
• Privacy Cookbook
• PrivacyTools
• PrismBreak (Non-trusted apps and more privacy-friendly alternatives)
• DeviceInfo - check information about system, browser, network and settings
• Joinfediverse Wiki - avoiding Big Tech manuals + links to further resources
• IP, DNS and information leak checker
• Browserleaks - check leaked information
• AmIUnique (browser fingerprint)
• Online accounts deletion: JustDeleteMe
• Online accounts deletion: AccountKiller
• Internet Noise Generator (+links to other tips)
• NoMoreGoogle (Google services alternatives)
• Pi-Hole (blocking unwanted domains)
• GNUnet
• Fediverse - decentralized social media networks
• Self-hosted Searx search engine
• Why you should't trust Discord
• Debian Paranoid Security Guide
• SecurityInABox - Security guide
• Liberate Android system
• Exodus (Android apps privacy)
• TheyTrackYou (privacy-related news + further links + some practical tips)
• TheTinHat (articles + tutorials)
• Email protection tips (by FSF)
• Don't use Windows 10
• Atlas of Surveillance (by EFF)
• Companies buying/selling personal data/profiles
• Glenn Greenwald - Why Privacy Matters (TED talk)
• The Eternal Value of Privacy
• TheNewOil - value of data
• Children's Privacy vs Social Media
• Privacy/security/OSINT podcast
• ChoosePrivacyEveryday (Articles + links to further resources)
• About end-to-end encryption in messengers
• Privacy International
• Richard Stallman's personal site
• Yarmo Mackenbach's blog about privacy and decentralization
• MyShadow - about digital traces

It will be constantly updated...