- Disable split tunneling in VPN client policy and verify the client enforces it rather than merely requesting it.
- Full-tunnel decisions carry bandwidth and cloud-performance costs; where selective tunneling is adopted anyway, the design needs documented compensations, not silence.
3.13.7OFFICIAL STATEMENT BELOWDERIVED REQUIREMENTPENDING NIST SME REVIEW
3.13.7 — Split tunneling prevention
3.13 System and Communications Protection · NIST SP 800-171 Rev. 2 · The heading label is this site's navigational shorthand; the official language is the statement below.
Official requirement statement (verbatim)
Prevent remote devices from simultaneously establishing non-remote connections with organizational systems and communicating via some other connection to resources in external networks (i.e., split tunneling).
NIST SP 800-171 Rev. 2 — Protecting CUI in Nonfederal Systems ↗NIST SP 800-171A — Assessing Security Requirements for CUI ↗Independent interpretation
What this requirement is after
A remote device connected to the organization must not simultaneously bridge to other networks. Split tunneling turns every remote laptop into a router between the internet and the internal network, bypassing the boundary protections everything else assumes.
Across revisions
Withdrawn as a standalone in Rev. 3 (03.13.07); the split-tunneling concern folds into Boundary Protection (03.13.01).
Mapped practices
Brilliant at the Basics practices that support this requirement
No practice maps to this requirement — deliberately.
The campaign’s twenty practices are a priority list, not a control catalog, and none of them works this requirement’s substance directly. It still applies to you if it is in your contract’s scope: address it through your own implementation and the related artifacts below, and treat the absence of a mapping here as honesty, not permission to skip it.
Doing the work
Implementation considerations and evidence
- VPN client configuration showing split tunneling disabled, or the documented alternative design
- A dated check that the policy deploys to all remote-access profiles
Artifacts
Templates and worksheets with a mapped relationship
No artifact in the library names this requirement yet. The library index groups everything by category and practice.
The other revision
Where this lands in Rev. 3
Provenance
Sources and review status
| Primary sources | NIST SP 800-171 Rev. 2 — Protecting CUI in Nonfederal Systems · NIST SP 800-171A — Assessing Security Requirements for CUI |
|---|---|
| Review status | Pending NIST SME review |
| Content version | 1.0 |
| Updated |