Linux Server Hardening
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Lesson 4 of 13 · Shrinking the surface

Firewall — nftables and firewalld with a "deny all" policy

45 min Debian 12 Versions Debian 12, Ubuntu 24.04, Rocky 9

Objective

Put in front of every service a firewall that denies everything by default and opens only what is justified, with nftables (Debian, Ubuntu) and firewalld (Rocky), testing the configuration before applying it.

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