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.

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This challenge was created by a community author. Community content is reviewed by the iximiuz Labs team on a best effort basis.

Challenge, Easy, on Programming, Linux

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.

#c #gcc #assembly #optimization

This challenge was created by a community author. Community content is reviewed by the iximiuz Labs team on a best effort basis.

Challenge, Easy, on Programming, Linux

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.

#c #gcc #preprocessor #macros

This challenge was created by a community author. Community content is reviewed by the iximiuz Labs team on a best effort basis.

Challenge, Medium, on Programming, Linux

Write a C Program Without a main() Function

by Başar Subaşı

Produce a valid ELF binary that runs and exits cleanly, but does not define a main() function.

#c #gcc #assembly #linker #elf

This challenge was prepared for you by the iximiuz Labs team.

Challenge, Easy, on Linux

SSH 101: Replace Password-Based Root Access with a Key-Based Admin Login

by Ivan Velichko

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.

#ssh #server-hardening

This challenge was prepared for you by the iximiuz Labs team.

Challenge, Medium, on Networking, Linux

Reach a Remote Loopback Port Through an SSH Jump Host

by Ivan Velichko

An inventory service lives inside a private VPC and keeps its debugging port bound to 127.0.0.1. Use SSH local port forwarding with a jump-only bastion to query the debugging port from your workstation.

#ssh #tunnel #port-forwarding #bastion #jump-host

This challenge was prepared for you by the iximiuz Labs team.

Challenge, Medium, on Networking, Linux

Reach Internal Servers Through a "No Shell" SSH Bastion

by Ivan Velichko

The application fleet lives inside a private VPC, reachable only through a locked-down bastion that refuses to give you a shell. Find a way to jump through the bastion and place a maintenance lock on two misbehaving servers.

#ssh #bastion #jump-host #debugging

This challenge was prepared for you by the iximiuz Labs team.

Challenge, Hard, on Networking, Linux

Restrict SSH Bastion Access by User Role

by Ivan Velichko

Harden a bastion host so only admins can get a shell on it, operators can open tunnels to arbitrary destinations, and developers can reach only the one internal service they actually need.

#ssh #tunnel #port-forwarding #bastion

This challenge was prepared for you by the iximiuz Labs team.

Challenge, Easy, on Networking, Linux

Access an Internal Debug Port Through an SSH Tunnel

by Ivan Velichko

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.

#ssh #tunnel #port-forwarding

This challenge was prepared for you by the iximiuz Labs team.

Challenge, Medium, on Networking, Linux

Reach a Private VPC Service Through an SSH Bastion

by Ivan Velichko

A production search cluster lives inside a private VPC and is reachable only from within it. Use SSH local port forwarding through a public-facing bastion host to query the cluster's API from your dev machine.

#ssh #tunnel #port-forwarding #bastion

This challenge was prepared for you by the iximiuz Labs team.

Challenge, Medium, on Networking, Linux

Expose a Local Service Through an SSH Reverse Tunnel

by Ivan Velichko

A payment webhook receiver runs as a local build on your dev machine, bound to 127.0.0.1 and invisible from the Internet. Use SSH remote port forwarding to publish it on a public-facing gateway VM so a test payment provider can reach it.

#ssh #tunnel #port-forwarding