NIST SP 800-171 Rev. 3 3.10.8 — Access Control for Transmission

What this control requires

This control requires controlling physical access to system distribution and transmission lines within organizational facilities to prevent accidental damage, disruption, or tampering. Safeguarding measures include locked spare jacks, secured wiring closets, cable protection, and wiretapping sensors to ensure the integrity and confidentiality of transmissions. This control supports the Physical Access Control capability within the Physical Protection (3.10) family.

In plain English

This control requires controlling physical access to system distribution and transmission lines within organizational facilities to prevent accidental damage, disruption, or tampering. In practice, this means you can prove you access management-level controls on a defined cadence.

Why it matters

DoD contractors and their subcontractors must implement all 100 SP 800-171 requirements to keep CUI handling contracts. Gaps are scored against the SPRS scoring methodology; below a 110-point starting score, each unmet requirement deducts points and a below-threshold score can disqualify a bid.

This control is rated high. Auditors expect a named owner, a remediation SLA, and a tooling artefact that evidences continuous operation.

What an auditor looks for

A C3PAO conducting a CMMC Level 2 assessment uses NIST SP 800-171A objectives. They expect a System Security Plan (SSP), Plan of Action & Milestones (POA&M) for any gaps, and objective evidence (configurations, ticket records, training records) for every requirement.

Within Physical Protection, the assessor will trace your implementation back to the catalogue reference (Requirement 3.10.8) and look for objective evidence on the latest two assessment cycles.

How to implement

Physical Security

Inheritance. For cloud-only operations, inherit physical controls from the provider's SOC 2 / ISO 27001 report and document the inheritance in the SoA.

Operational checklist

• Access. Document the trigger, the owner and the cadence.
• Access Control. Document the trigger, the owner and the cadence.
• Protection. Document the trigger, the owner and the cadence.
• System. Document the trigger, the owner and the cadence.
• Physical. Document the trigger, the owner and the cadence.
• Scope: management, security, physical access, access control, transmission, cable protection.

Evidence to collect

• Identity Scan. IAM / IdP exports — Entra ID, Okta, IAM Identity Center, Workspace directory — showing accounts, roles, MFA state and last sign-in.

Identity analytics (Okta, SailPoint, Access Analyzer) demonstrates least-privilege. Focus: Access Control for Transmission.

How it maps to other frameworks

Computed from shared tags, control component and key-operation subjects — handy when you are reconciling controls across an audit.

• NIST SP 800-53 Rev. 5 PE-2(2) — Two Forms Of Identification
• BSI C5:2020 PS-04 — Physical site access control
• SOC 2 (2017 TSC) CC6.6 — Boundary Protection
• CIS Controls v8 6.7 — Centralize Access Control
• ISO/IEC 27001:2022 A.5.15 — Access control

Related controls in NIST SP 800-171 Rev. 3

• Requirement 3.10.1 — Physical Access Authorizations
• Requirement 3.10.7 — Physical Access Control
• Requirement 3.1.11 — Session Termination
• Requirement 3.1.6 — Least Privilege - Privileged Accounts
• Requirement 3.1.8 — Unsuccessful Logon Attempts
• Requirement 3.13.4 — Information in Shared System Resources

References

• NIST Computer Security Resource Center — NIST SP 800-171 Rev. 3
• Catalogue identifier: Requirement 3.10.8

Topics: identity accessphysical securityidentity managementaccess reviewprivileged access