Starting with FF 32, it's on by default, so you don't have to do anything. The pinning level is enforced by a pref, security.cert_pinning.enforcement_level
* 0. Pinning disabled* 1. Allow User MITM (pinning not enforced if the trust anchor is a user inserted CA, default)* 2. Strict. Pinning is always enforced.* 3. Enforce test mode.
== More information ==