Works on the server, refused from outside
Reproduce the classic failure — an API that answers on the loopback and refuses everyone else — prove the bind with ss, fix it in the service's environment, and catch the inverse mistake: a database published on every address.
20 minutesTechnical content last reviewed on 17 Sept 2026
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What this lesson builds
- Working out why a service cannot be reached
- Knowing what the machine exposes, and closing the rest