What this requirement asks
Verify and control/limit connections to and use of external systems.
This is a CMMC Level 2 requirement in the Access Control family, drawn from NIST SP 800-171 Rev. 2. An assessor evaluates it objective by objective — every objective below must be supported by evidence, not just described in a policy.
Assessment objectives (6)
- 3.1.20[a] — connections to external systems are identified
- 3.1.20[b] — the use of external systems is identified
- 3.1.20[c] — connections to external systems are verified
- 3.1.20[d] — the use of external systems is verified
- 3.1.20[e] — connections to external systems are controlled/limited
- 3.1.20[f] — the use of external systems is controlled/limited
What an assessor examines
Examine:
- Access control policy
- procedures addressing the use of external systems
- terms and conditions for external systems
- system security plan
- list of applications accessible from external systems
- system configuration settings and associated documentation
- system connection or processing agreements
- account management documents
- other relevant documents or records
Interview:
- Personnel with responsibilities for defining terms and conditions for use of external systems to access organizational systems
- system or network administrators
- personnel with information security responsibilities
Test:
- Mechanisms implementing terms and conditions on use of external systems
Evidence that defends it
Define allowed external services; enforce via egress controls
Check your readiness
Score this requirement against your own environment with the Level 2 self-assessment checklist, or estimate your SPRS score with the free CMMC compliance tool. Self-reported answers are planning signals only — they do not establish a verified or assessor-accepted result.