CMMC Practice SC.L2-3.13.6
Network Communication by Exception: Deny network communications traffic by default and allow network communications traffic by exception (i.e., deny all, permit by exception).
Monarch ISC Guidance
Discussion From Source
References
- NIST SP 800-53 Rev 4 SC-7(5)
- NIST SP 800-171 Rev 2 3.13.6