Topic Overview
Linux
Filesystem, permissions, SSH, systemd, logs.
Linux Filesystem Permissions — rwx, chmod, chown, and sudo Hygiene
Complete beginner guide to Linux file permissions, user/group ownership, chmod and chown commands and flags, umask, and safe sudo rules.
SSH Hardening — Keys, sshd_config, and Brute-Force Protection
Complete step-by-step guide to securing SSH access on Linux servers using Ed25519 keys, disabling passwords, hardening daemon configuration, and testing.
systemd Services and Timers — systemctl Survival Guide
Complete beginner guide to managing Linux background services, writing custom systemd unit files, viewing journalctl logs, and replacing cron with timers.