/$$ /$$ /$$ /$$ | $$$ | $$ | $$ | $$ | $$$$| $$ /$$$$$$ /$$$$$$ /$$ /$$ /$$ /$$$$$$ /$$$$$$ | $$ /$$ /$$$$$$$ | $$ $$ $$ /$$__ $$|_ $$_/ | $$ | $$ | $$ /$$__ $$ /$$__ $$| $$ /$$/ /$$_____/ | $$ $$$$| $$$$$$$$ | $$ | $$ | $$ | $$| $$ \ $$| $$ \__/| $$$$$$/ | $$$$$$ | $$\ $$$| $$_____/ | $$ /$$| $$ | $$ | $$| $$ | $$| $$ | $$_ $$ \____ $$ | $$ \ $$| $$$$$$$ | $$$$/| $$$$$/$$$$/| $$$$$$/| $$ | $$ \ $$ /$$$$$$$/ |__/ \__/ \_______/ \___/ \_____/\___/ \______/ |__/ |__/ \__/|_______/
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The seven-layer framework that underpins all networking — understand how data flows from application to wire and back.
cd /learn/essentials/networks/osi-model/ _/$$ /$$ /$$ /$$ /$$ | $$ |__/ | $$$ | $$ | $$ | $$ /$$ /$$$$$$$ /$$ /$$ /$$ /$$ | $$$$| $$ /$$$$$$ /$$$$$$ | $$ | $$| $$__ $$| $$ | $$| $$ /$$/ | $$ $$ $$ /$$__ $$|_ $$_/ | $$ | $$| $$ \ $$| $$ | $$ \ $$$$/ | $$ $$$$| $$$$$$$$ | $$ | $$ | $$| $$ | $$| $$ | $$ >$$ $$ | $$\ $$$| $$_____/ | $$ /$$ | $$$$$$$$| $$| $$ | $$| $$$$$$/ /$$/\ $$ | $$ \ $$| $$$$$$$ | $$$$/ |________/|__/|__/ |__/ \______/ |__/ \__/ |__/ \__/ \_______/ \___/
IP addresses, ping, curl, ports, routes — the essential Linux commands for diagnosing and managing network connectivity.
cd /labs/linux-networking/ _
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How ping works under the hood — ICMP echo requests and replies, TTL, reading output, failure modes, and diagnostic techniques.
cd /labs/ping/ _
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How Linux firewalls work — iptables chains, rules, targets, and the critical concept of rule ordering that determines what gets through.
cd /labs/firewalls-iptables/ _