Linux
Xtables-addons: GeoIP, TARPIT and the psd Module I Ported
Extra iptables matches and targets the kernel never shipped: country blocking with geoip, a TARPIT decoy port, port knocking, and the psd scan detector I ported.
Category
Linux
Linux and the command line: system administration, processes, services, networking and everyday tools.
Linux
rsync Recipes: Trailing Slashes, --delete and Filters
One missing slash nests a directory. One empty source wipes a backup. Tested rsync recipes for mirroring, filtering, verifying and copying over SSH.
Linux
Docker Volumes vs Bind Mounts, and the File Ownership Trap
Why a volume shows the image's files and a bind mount hides them, and how a root container leaves files your own user cannot edit or delete. Four tested fixes.
Linux
systemd Timers: A Practical Replacement for Cron Jobs
Cron loses output, overlaps jobs and skips runs while the machine is off. systemd timers fix all three. A tested walk-through with OnCalendar examples.
Linux
Docker Multi-Stage Builds: Smaller Images, Same Result
The same 147 kB binary in a 257 MB image or an 8.44 MB one. Multi-stage builds, named stages, a --target debug image, and why build secrets still leak.
Linux
Dockerfile Layer Caching: Order Instructions for Fast Rebuilds
A one-line code change should not reinstall every dependency. Timed rebuilds show how instruction order, .dockerignore and ARG placement decide what Docker reuses.
Linux
Find Which Process Is Listening on a Port in Linux
"Address already in use" again? How to find the owner of a port with ss, lsof and fuser, decode /proc/net/tcp by hand, and why some ports show no process.