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6.10 Journal: the Linux half exists

Lesson 0.4 predicted that by about now you'd be writing these without being told. If that's true, write yours and skip the prompts below. If it isn't yet, that's fine, and here they are.

Permanent note. Add to Projects/lab-network.md, or start Projects/ubnt01.md:

  • UBNT01 at 10.10.10.20, its username, and that it authenticates by SSH key with passwords disabled
  • Where ~/docker lives and which stacks are in it
  • The Gitea URL, your admin account, and where the data directory sits
  • The DNS record you added, so future-you knows records are added on DC01 and not somewhere on the Linux box

Daily note, four headings.

Under what I did: the server built, hardened, containerised, and turned into the home for your own notes.

Under what broke: netplan indentation is the classic, and so is enabling ufw before allowing SSH. If you locked yourself out and recovered through the hypervisor console, write down exactly how, because that's the recovery path for every future lockout.

Under what I learned: explain the difference between a container and a virtual machine in your own words, and why services in this lab publish to 127.0.0.1 instead of 0.0.0.0. Those two answers come up in interviews constantly.

Under open questions: "how do I get a certificate my machines actually trust" is the right one to be sitting with, and Module 7 is entirely about it.

Then commit and push, and notice that this push goes somewhere new:

cd ~/git/lab-journal
git add -A
git commit -m "journal: module 6, UBNT01 built and hosting my notes"
git push                 # to your own server now
git push github main     # and the off-lab copy

Tick Module 6 in Projects/lab-progress.md, and snapshot UBNT01 as docker-and-gitea. Unlike DC01, this machine is safe to snapshot freely; the warning in lesson 5.12 was specific to domain controllers.