Foundations
4–8 weeks · skip anything you already knowEvery later lab assumes you can read a packet capture, move around a Linux shell, and script a repetitive task. Do only the items that are actually gaps.
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Professor Messer — CompTIA Network+ (N10-009) video course
TCP/IP, subnets, routing, switching, DNS, VPNs, wireless. Watch at 1.5×; you do not need the exam, just the mental model.
Or, if you prefer doing to watching: Cisco Networking Academy — Networking Basics (≈ 22 h, Packet Tracer labs, shareable badge) -
Cisco Networking Academy — Linux Unhatched
The command line, files, permissions and processes in one sitting.
Or, to go deeper at your own pace: Linux Journey (now hosted by LabEx; short lessons from the shell through to the kernel) -
OverTheWire — Bandit
The classic command-line wargame. Finish it before touching any course with "hacking" in the title.
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Automate the Boring Stuff with Python
Enough Python to write your own tooling, parse logs and script the repetitive parts of every lab.
Never programmed? Do Harvard CS50's Introduction to Programming with Python instead (≈ 10 weeks, graded problem sets, free certificate) -
Microsoft Learn — PowerShell modules
Most corporate incidents happen on Windows. Learn to drive it from the shell before you try to defend or attack it.
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TryHackMe — Pre Security path
Networking, web, Linux and Windows fundamentals as guided, browser-based rooms. Good if you prefer doing to watching.