fail open vs. fail closed
expressionsecuritynetworking
The design choice of what a control does when it breaks: allow everything through, or block everything.
A fire door fails open because life beats security; a vault fails closed for the opposite reason. Every inline control faces the same choice - an IPS that fails open keeps the business running but unprotected, while failing closed is safe and is also an outage. The right answer is a decision, never a default.
Also known as: fail-safe vs. fail-secure, fail open, fail closed