Deny network traffic by default and allow by exception
System and Communications Protection · NIST SP 800-171 Rev 2
Requirement
Deny network communications traffic by default and allow network communications traffic by exception (i.e., deny all, permit by exception).
Discussion
This requirement applies to inbound and outbound network communications traffic at the system boundary and at identified points within the system. A deny-all, permit-by-exception network communications traffic policy ensures that only those connections which are essential and approved are allowed.
How this affects your SPRS score
Under the DoD Assessment Methodology, a perfect SPRS score is 110. If this control is not met, 5 points is subtracted from your score.
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Estimate my SPRS score →Source: NIST SP 800-171 Rev 2 (public domain) · SPRS weighting per the DoD Assessment Methodology · This is reference information, not an official assessment.