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).
Links to Publicly Available Resources
CMMC CLARIFICATION (Ref CMMC – Appendix B)
Block all traffic going into and coming out of the network, but permit specific traffic into and coming out based on the organization’s policies, exceptions, or criteria. This process of permitting only authorized traffic to the network is called whitelisting which limits the number of unintentional connections to the network.