Sysadmin

Cockpit Project [HN]

Interactive, file-level Time Machine-like tool for ZFS [HN]

ZFS for Dummies[HN]

OpenSSH configuration directives from Mozilla

lnav: An advanced log file viewer for the small-scale

HTTP / Nginx

Nginx Cheatsheet [reddit]

Mozilla SSL Configuration Generator

Common Nginx misconfigurations that leave your web server open to attack [HN]

Gixy: Nginx configuration static analyzer

System hardening

Linux Hardening Guide [HN] (2022)

Debian: hardening guide and what not to do to break the security/stability of a debian system

Networking

OpenSnitch: Applications firewall, similar to LittleSnitch

Headscale: Open-source implementation of the Tailscale control server [HN] (discussion of similar alternatives in HN thread)