Linux mastery challenges
The hardest level: undocumented systems, missing tools and time pressure, and you find solutions at every layer from kernel to application.
Level 501 · 13 lessons · 12 practice labs
Lessons
With few tools
- Troubleshooting on a system with only busybox
- The package manager is broken: repairing by hand
- Reconstructing a running process's story from /proc alone
- Short task: produce a server status report with only three tools
Deep layers
- A system that won't boot because a module is missing from the initramfs
- Diagnosing a hung kernel from traces
- Catching an invisible delay with eBPF
- A service starved by an invisible cgroup limit
- Short task: draw a layer-by-layer root cause diagram
Big scenarios
- Day one in an undocumented data centre
- A cascading outage lasting hours
- Rebuilding the platform under time pressure
- Capstone: a twelve-hour mastery exam
Practice labs
- Troubleshoot with busybox only: On a system with only busybox find the full partition and the process filling it.
- Repair a broken package manager by hand: Repair a package manager that cannot run because its own library is damaged by unpacking package files by hand, and verify the database.
- Produce a server status report with only three tools: Using nothing beyond shell built-ins, cat and /proc, produce a report covering processes, memory, mounts and network connections.
- Reconstruct a running process's story from /proc alone: Determine from /proc entries alone when, by whom, from which directory and with which files a process was started.
- Rescue a system that will not boot on a missing module from the initramfs shell: In the initramfs shell determine why the root device is not found, boot the system by hand and rebuild the image with the missing module.
- Diagnose a hung kernel from traces: From task dumps and lock information taken over the serial console, identify with evidence the subsystem causing the hang and the workload triggering it.
- Catch an invisible delay with eBPF: Use ready eBPF tools to find in which kernel path an intermittent delay invisible in the metrics arises.
- Find a service starved by an invisible cgroup limit: On a service that runs slowly though CPU looks idle, read the throttling counters, find the limit inherited from a parent slice and fix it.
- Draw a layer-by-layer root cause diagram: For a fault spanning application to kernel to hardware, write a diagram showing the evidence gathered and the hypothesis eliminated at each layer.
- Map an undocumented environment on day one: In an environment with no documentation determine server roles, data flow and the identity source by observation alone.
- Set the right priorities in a cascading outage: In four faults triggering each other work out the dependency order, pick the one to fix first and prove the reasoning.
- Rebuild the platform under time pressure: In the Saklıvadi Üniversitesi scenario rebuild identity, storage and web tiers from backups and notes in the right order and pass the checker.
About this course
The hardest level: undocumented systems, missing tools and time pressure, and you find solutions at every layer from kernel to application.
What you will learn
- With few tools
- Deep layers
- Big scenarios
Prerequisites
You should be experienced in the topics of the same path up to level 401.
Lab environment
Lessons run in your own Kali Linux terminal that opens in the browser. Nothing to install; the lab starts clean in every lesson.
Frequently asked questions
- Is this course right for my level?
- The course is at level 501; it assumes you know the topics of the lower-level courses.
- Is there anything to install?
- No. Every lesson runs in your own lab environment that opens in the browser.
- How do lessons work?
- Each lesson has 8 to 10 steps and a short quiz. Early steps show the command to type, later steps give less help; if two attempts fail, the solution opens.
- Can I try it for free?
- Yes. The first three lessons of every course are free.