Hi everyone. I'm new here and still learning, so please bear with me 😅.

I've been trying to self-host some AI agents and started with the usual port-based firewall rules (like allowing outbound 443/tcp). But the agents kept failing in weird ways. I realized they weren't just hitting major CDNs—they were calling out to specific APIs and services I hadn't anticipated.

So I switched to FQDN allowlists. Instead of opening a wide port, I only allow the exact domains the agent runtime actually needs (like `api.openai.com` and `objects.githubusercontent.com`). It was more work upfront, but:

- It stopped "phone home" calls to metrics services I didn't know about.
- Updates are clearer now—I check the new domains in a test run before updating the allowlist.
- Feels more minimal and secure.

Has anyone else done this? I'd love an ELI5 on best practices for maintaining these lists as runtimes update. Thank you!