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Free, practical cybersecurity cheat sheets — the commands, flags and checklists worth coming back to, each with a visible last-verified date and none of it behind an email form or a PDF wall.
New here? The Cyber Kill Chain maps every sheet below onto a stage of a real attack — a good place to start.
The offensive chain runs end to end: map a target with the OSINT & recon sheet, scan it with Nmap, make sense of what's open via common ports, catch a shell with the reverse shell sheet, then climb with Linux privilege escalation.
The AI-security set covers what everyone's asking about: the OWASP LLM Top 10, prompt injection, jailbreak techniques, AI agent security and RAG security — with a hands-on LLM security lab to practise on.
On the blue-team side, watch the wire with tcpdump, read Linux logs with journalctl, search them at scale with SPL, and triage a suspicious file safely with malware analysis sandboxes. Everything is written to be scanned in seconds and trusted — spot something out of date? Tell me.

Reference

Install Software Safely: Sources, Hashes, Signatures and Licenses (Tech+)

ExplainerPartly testedLevel beginnerTime ~25 minTool PowerShell, winget, aptCost freeExam Tech+ 3 What you’ll know Where safe software comes from, how to prove a download is the…

Reference

Programming Languages Compared: Compiled, Interpreted, Markup and Query (Tech+)

ExplainerPartly testedLevel beginnerTime ~25 minTool Python, gcc, Bash, PowerShell, SQLiteCost freeExam Tech+ 4 What you’ll know The difference between compiled, interpreted, scripting, markup and query languages;…

Reference

Lock Down Your Own Devices: Updates, MFA, Encryption and Backups (Tech+)

ExplainerPartly testedLevel beginnerTime ~20 minTool Windows Settings, PowerShellCost freeExam Tech+ 6 What you’ll know The eight habits that protect a computer or phone: updates, antivirus, a…

Reference

NTP and Time Sync Explained: Stratum, Offset and Why Logs Need the Right Time (Network+)

ExplainerLevel beginnerTime ~10 minTool timedatectl, w32tmCost freeExam N+ 3 · also 5 What you’ll know How the Network Time Protocol keeps clocks in step, what stratum,…

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Spanning Tree (STP) Explained: Build a Switch Loop and Watch STP Fix It (Network+)

ExplainerLevel beginnerTime ~15 minTool ip, bridge (Linux)Cost freeExam N+ 2 · also 5 What you’ll know Why two cables between switches can take a network down,…

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The OSI Model Explained: One Web Request Through All 7 Layers (Network+)

ExplainerLevel beginnerTime ~20 minTool ip, curl, tcpdumpCost freeExam N+ 1 · also 5 What you’ll know The seven OSI layers, what each one does, which devices…

Reference

Incident Response Explained: The Six Steps and Evidence Basics (Security+)

ExplainerLevel beginnerTime ~15 minTool PowerShell, bashCost freeExam Sec+ 4 What you’ll know The six phases of incident response in order, what happens in each, how to…

Reference

Email Security Explained: SPF, DKIM and DMARC (Security+)

ExplainerLevel beginnerTime ~12 minTool dig, PowerShellCost freeExam Sec+ 4 · also 2 What you’ll know Why anyone can type any “From” address, how SPF, DKIM and…

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Risk Management Explained: SLE, ALE, RTO and the Four Responses (Security+)

ExplainerLevel beginnerTime ~15 minTool PythonCost freeExam Sec+ 5 · also 4 What you’ll know How to put a dollar figure on a risk, the four ways…

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Cryptography and PKI Explained: Hashing, Encryption and Certificates (Security+)

ExplainerLevel beginnerTime ~20 minTool OpenSSL, PowerShellCost freeExam Sec+ 1 · also 3, 4 What you’ll know The difference between hashing and encryption, symmetric vs asymmetric keys,…

Reference

Data and Databases Explained: Tables, SQL and Backups (Tech+)

ExplainerLevel beginnerTime ~15 minTool Python, SQLiteCost freeExam Tech+ 5 What you’ll know Why data is worth protecting, structured vs unstructured data, how a database table works…

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Programming Basics Explained: Variables, Loops and Functions (Tech+)

ExplainerLevel beginnerTime ~15 minTool Python, PowerShellCost freeExam Tech+ 4 What you’ll know What variables, data types, branches, loops, functions and objects are; the difference between compiled,…

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Operating Systems, Software and File Systems Explained (Tech+)

ExplainerLevel beginnerTime ~12 minTool PowerShell, bashCost freeExam Tech+ 3 What you’ll know What the operating system does for you, how the main ones differ, why a…

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Computer Hardware Explained: CPU, RAM, Storage and Ports (Tech+)

ExplainerLevel beginnerTime ~15 minTool PowerShell, bashCost freeExam Tech+ 2 What you’ll know What each main part of a computer does, how to tell a fast drive…

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Binary, Hex and Data Sizes Explained (Tech+)

ExplainerLevel beginnerTime ~12 minTool PowerShell, bashCost freeExam Tech+ 1 What you’ll know What a bit and a byte are, how to read binary and hex, why…

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Network Security Explained for Network+: Attacks, AAA and Hardening

ExplainerTime ~20 minCost freeExam N+ 4 What you’ll know The ideas behind Network+ Domain 4: the CIA triad, AAA and 802.1X, the attacks the exam names…

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High Availability, Disaster Recovery and Network Documentation (Network+)

ExplainerTime ~15 minCost freeExam N+ 3 What you’ll know How to measure availability and recovery, how networks avoid single points of failure, how to back up…

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Cloud Networking and SDN Explained (Network+)

ExplainerTime ~15 minCost freeExam N+ 1 · also 2, 4 What you’ll know What the cloud service models mean, how a cloud network (a VPC) is…

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Network Cabling and Connectors Explained (Network+)

ExplainerTime ~15 minTool ethtool, Get-NetAdapterCost freeExam N+ 1 · also 2, 5 What you’ll know Which copper category carries which speed and how far, when fiber…

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Wi-Fi Standards, Bands and Channels Explained (Network+)

ExplainerTime ~15 minTool netsh, nmcliCost freeExam N+ 2 · also 1, 4, 5 What you’ll know Which Wi-Fi standard is which, why 2.4 GHz is crowded…

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Bash Guide

Straightforward guide to bash fundamentals and scripting. Covers shell basics, variables, control flow, functions and common patterns. Useful for anyone writing infrastructure code, automation or incident…

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90 Days of Cybersecurity, Hands-On: Free Labs for Every Block

CompanionBlocks 11Cost freePace your ownNot affiliated 0 / 11 steps What this is 90DaysOfCyberSecurity is one of the most popular free study plans on GitHub (about…

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Bug Bounty Platforms Compared: Where to Start

ReferenceFormat platform tiersTopic bug bountyCost free to start There are a lot of bug bounty and crowdsourced-security platforms, and a list of logos tells you nothing…

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Study Once, Earn Two: How Cybersecurity Certs Stack, Renew Each Other and Shorten the CISSP Clock

ReferenceCareer · certificationsLevel Beginner to intermediateWritten guide · no lab neededExam Security+ · CySA+ · PenTest+ · CISSP Most cert advice treats every exam as its…

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OWASP/wstg

A structured framework for web application security testing, covering reconnaissance through post-test activities. Organized by testing category rather than vulnerability type, making it practical for both…

Reference

HackTricks-wiki/hacktricks

A sprawling wiki of tactics and techniques gathered from CTFs, penetration tests, and security research. Covers everything from basic enumeration to privilege escalation and post-exploitation across…

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EvanThomasLuke/Awesome-AI-Security-Skills

Curated list of skills, tools, and resources for security work involving AI systems. Covers threat modeling, red-teaming, prompt injection, model extraction, and defensive practices. Useful for…

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LOLBAS-Project/LOLBAS

A curated collection of legitimate Windows binaries and scripts that attackers abuse to evade detection and achieve their objectives. Each entry documents the binary, its abuse…

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danielmiessler/SecLists

A comprehensive collection of wordlists, payloads, and patterns organized by type and use case. Covers usernames, passwords, fuzzing inputs, sensitive data signatures, web shells and more.…

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GTFOBins/GTFOBins.github.io

A searchable reference of Unix binaries that can be abused to escape restricted environments or escalate privilege. Covers common tools like find, tar, and sudo with…