Count Optimized Assembly Instructions
by Başar Subaşı
Compile a small C loop with -O2 -S, inspect the generated assembly, report how many add instructions gcc produced and see how much it has optimized the equasion.
Submissions: 19/27
Challenges
Focused hands-on problems designed to help you hone your DevOps or Server Side skills. Some challenges are more educational, while others are based on real-world scenarios. The platform provides hints and feedback for each challenge, including automated solution checks.
Inspect a Preprocessor Macro Expansion
by Başar Subaşı
Run gcc -E on a small C program and find the exact line where the preprocessor expanded a macro into a printf call.
Submissions: 25/48
Challenge, Easy, on
SSH 101: Replace Password-Based Root Access with a Key-Based Admin Login
A newly provisioned server is reachable as root with a shared seed password. Create a sudoer admin user, switch SSH to key-based access, disable password and root logins, and retire the seed credential.
Submissions: 89/262
Access an Internal Debug Port Through an SSH Tunnel
A remote VM serves an app on port 80 and keeps an internal debugging port bound to 127.0.0.1. Reach the debugging port from your workstation using an SSH tunnel, without exposing it on the VM's external interface.
Submissions: 118/161
Write a TCP Client for a Telemetry Server
Write your first TCP client for a push-only telemetry server that starts sending sensor readings as soon as you connect. Likely the easiest way to get started with TCP socket programming.
Challenge, Easy, on
Troubleshoot a Worker Service That Keeps Disappearing
A systemd-managed worker process starts cleanly, prints a few heartbeat lines, then silently vanishes - over and over again. Diagnose why the process keeps dying and stabilize the service.
Submissions: 169/229
Challenge, Easy, on
Troubleshoot an Image Conversion Daemon
An image conversion daemon was installed from a vendor package, but it fails to start. Diagnose why the binary cannot be loaded and fix the installation.
Submissions: 147/185
Challenge, Easy, on
Troubleshoot a Log Shipping Daemon That Refuses to Start
A system daemon crashes on startup with a cryptic, non-actionable error message. Investigate the failure, identify its root cause, and get the service running.
Submissions: 159/219
Challenge, Easy, on
Create a systemd Service for a Long-Running Process
Turn a plain HTTP server binary into a proper systemd-managed service that starts on boot and is automatically restarted when it crashes.
Submissions: 253/329
Challenge, Easy, on
Run an ARM64 Binary on an AMD64 Machine Using QEMU Emulation
Learn how Linux's binfmt_misc mechanism and QEMU user-space emulation allow transparent execution of binaries compiled for foreign CPU architectures.
Submissions: 126/159