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01 — Linux Fundamentals

01 — Linux kernel and architecture
02 — Linux boot process
03 — Filesystem concepts
04 — Linux process model
05 — Users, groups, and permissions
06 — I/O, file descriptors, and streams
07 — Package management

02 — Shell Basics

01 — Shell environment and safe defaults
02 — Inspecting unknown content
03 — Text extraction and reshaping
04 — sed for streaming edits
05 — awk for fields and reports
06 — Sorting and deduplication
07 — Search basics (grep and ripgrep)
08 — Advanced grep, ripgrep, and regex
09 — Live log tailing
10 — jq for JSON
11 — yq for YAML
12 — Parallelism (xargs, parallel)
13 — Shell scripting structure

03 — Filesystem

01 — Finding files and metadata
02 — Filesystem literacy
03 — Comparing text and trees (diff / patch)
04 — Archives (tar)
05 — Compression tools

04 — Processes & Users

01 — Process listing and signals
02 — Users, groups, permissions
03 — Services (Linux, systemd)
04 — Scheduling: cron, crontab, launchd
05 — System introspection

05 — Networking Theory

01 — Well-known ports
02 — IP addressing and special ranges
03 — TCP and UDP fundamentals
04 — DNS record types and resolution
05 — IP routing fundamentals
06 — Application-layer protocols
07 — IPsec and VPN concepts

06 — Networking

01 — Local interfaces, routing, and ARP
02 — HTTP with curl
03 — Downloads with wget
04 — SSH config, keys, and agents
05 — rsync for sync
06 — DNS CLI (dig, host, nslookup)
07 — Reachability: ping, traceroute, mtr
08 — WHOIS-style text and registration fields
09 — TLS with openssl
10 — netcat / nc and socat
11 — tcpdump BPF basics and text output
12 — tshark decode workflows

07 — Exploitation

01 — nmap essentials
02 — Web content discovery
03 — CEWL-style wordlists
04 — Online brute-force tools
05 — High-speed scanning (masscan)

08 — Forensics

01 — Suspicious file analysis
02 — Web server log forensics
03 — Compromised host triage

Home Lab setup Stats Tools RTFM

RTFM

Quick-reference cheatsheets for tools used in security work.

nmap
Network mapper — host discovery, port scanning, OS and service detection.