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How-tos

Step-by-step guides, with code to copy.

  1. 21 min read

    Technitium DNS on Debian 13, locked down from first boot

    Install Technitium on Debian 13 and lock it down before the first client uses it: encrypted upstreams, DNSSEC validation, an ACL, rate limits and a firewall.

  2. 9 min read

    Firewall Docker-published ports with the DOCKER-USER chain

    Limit who can reach the ports your containers publish on Debian 13, with rules that survive reboots and don't break the containers' own outbound traffic.