# Network security: design boundaries you can verify

Original SecNet workpaper · 1.0 · 11 October 2026

Complete placeholders for your assessment. The example below is fictional; it is not an executed test or a legal decision.

## Assessment identity

- Record ID: [___]
- Objective and decision question: [___]
- Scope / exclusions: [___]
- Criteria and version: [___]
- Authorization and limits: [___]
- Owner / independent reviewer: [___]
- Period / artifact digest: [___]
- Evidence access / retention: [___]

## Planned procedure

1. Inventory assets, routes, identity systems, remote access and critical dependencies. Include cloud peering and management networks, not only office subnets.
2. Create an allowed-flow matrix: source zone, destination zone, service, identity, business owner and expiry. Remove rules without a justified purpose through change control.
3. Separate user, server, management and external paths according to risk. Restrict administrative access and document how emergency access is granted and reviewed.
4. Verify representative permitted and denied flows during an approved window. Capture the vantage point and topology version; one blocked ping is not proof of application isolation.
5. Correlate network telemetry with identities and response ownership. Tune actionable signals and retention rather than collecting payloads without a defined investigation use.
6. Exercise failover, backup restoration and rollback of network changes. Review stale access after incidents, supplier changes and major architecture updates.

## Evidence and decision register

| ID | Criterion | Observation | Redacted evidence / origin / time | Conclusion and limitation | Owner / date | Recheck |
|---|---|---|---|---|---|---|
| [___] | [___] | [___] | [___] | [___] | [___] | [___] |

## Topic-specific deliverables

- [ ] Current topology and allowed-flow matrix with owners.
- [ ] Segmentation test record including both allowed and denied cases.
- [ ] Detection/response exercise and network change rollback record.

## Worked fictional decision example

Fictional exercise: a contractor zone should reach a maintenance portal but not server administration. Test both intended paths from a contractor test endpoint. Record application-level results and rule references; repeat after a rule change. A test from an administrator laptop would use the wrong vantage point and could produce false assurance.

## Closure check

- [ ] Every rule has a business owner and purpose?
- [ ] Both permitted and denied paths tested?
- [ ] Telemetry reaches an accountable response team?

## Official references · checked: 2026-10-11

- [NIST SP 800-115](https://csrc.nist.gov/pubs/sp/800/115/final)
- [Nmap manual](https://nmap.org/book/man.html)
- [Wireshark guide](https://www.wireshark.org/docs/wsug_html_chunked/)
- [Zeek documentation](https://docs.zeek.org/en/current/)
- [Suricata documentation](https://docs.suricata.io/en/latest/)