Mission 5 · Build the boundaries
Close the side doors
Understand default-deny networking.
A compromised bot wants to upload a private chat to an unfamiliar website. You decide which outside connections its environment should be able to make.
Network gatekeeper
“Give me an explicit list. Everything not on it stays closed.”
The decision
Allow only the one route this bot needs in the guide’s design.
- Its own controlled proxy
The proxy checks destinations and supplies the real credentials. - Any website if the bot says it is useful
Let the model decide which sites are trustworthy. - A public DNS resolver
Let it look up arbitrary domain names directly. - The other friend’s proxy
Useful as a backup if its own one fails.
Reveal the explanation
One controlled exit. Requests still face the proxy’s checks, and other direct routes remain closed.
Default deny means ‘nothing is allowed unless we deliberately allow it.’ An allowlist is smaller than a list of every possible bad destination.- The friend’s network has no internet NAT, no external DNS, and a narrowly scoped network rule.
- DNS lookups can themselves carry encoded data, so ‘no web browsing’ is not the same as ‘no way out.’
- These restrictions are enforced by the network and proxy, not by trusting the model to behave.
Proxy
A controlled middle service that handles requests on another system’s behalf.