Deny-by-default
Also called: default deny, secure by default
Designing a system so that anything not explicitly permitted is refused — no capability, connection, or scope is granted implicitly.
The opposite of the configuration that causes most exposure incidents, where a service binds to 0.0.0.0, ships with auth off, or grants broad scopes unless told otherwise. Deny-by-default means an MCP server listens only on loopback until deliberately exposed, requires auth before doing anything, and holds no permissions it wasn't explicitly given.
Why it matters
The exposed MCP servers and gateways this project tracks are almost all allow-by-default deployments that nobody re-configured. Software that is deny-by-default fails safe: a forgotten instance is a useless instance rather than an open door.
Exposure map
Live counts of instances showing this pattern will appear here once the exposure map is collecting data.