TOPIC / CATEGORY
Notes in Linux & Systems
17 articles
fail2ban for SSH on Debian 13
Install fail2ban on Debian 13, understand the sshd jail the package already enables, tune bans in a local override, and check, test, and undo bans safely.
ufw Without Locking Yourself Out
Set up ufw on a Debian or Ubuntu VPS with SSH allowed first, a timed rollback in case a rule is wrong, and a clear view of the Docker ports ufw cannot see.
Unattended Upgrades You Can Actually Check
Enable automatic security updates with unattended-upgrades on Debian and Ubuntu, see exactly what it will install, pick a reboot policy, and confirm it really ran.
Add a Swap File to a Small VPS
Check memory first, create a swap file that survives reboots, set vm.swappiness with a sysctl drop-in, and remove it cleanly if you change your mind.
A Safe 90-Second Linux Disk Space Triage
A read-only sequence for finding what filled a Linux server before deleting logs, images, caches, or data you may still need.
systemctl cat and Drop-In Overrides
Inspect the complete systemd unit and make a small local override without editing vendor files.
systemd Timers Without the Guesswork
Create a small systemd timer, inspect its next run, and make missed jobs predictable after downtime.
A Calm SSH Host Key Check
Check what really changed when SSH warns about a new host key, before deleting the old entry from knownhosts.
When Cron Does Not Share Your Shell
Fix a script that works in your terminal but fails under cron by giving the job explicit paths, a small environment, and a log.
Reading a Failed systemd Service Without Scrolling Forever
A compact sequence for checking a failed systemd unit, its recent logs, and the exact configuration systemd loaded.