---
type: concept
tags: [parking, security, network, access-control]
sources: [parking-system-architecture]
updated: 2026-06-14
---

# Network Isolation

**Mandatory** mitigation for the unauthenticated [[uhppote-udp-protocol]]: because the
[[uhppote-controller]] can't authenticate, the **network must be the security boundary** (the
[[trust-boundary]] = the network). (See [[parking-system-architecture]] §6.)

- Control devices go on **their own VLAN** with **no route** to the booth/office network and
  **no wireless bridge**.
- Requires a **managed VLAN switch** (in the [[bom]]).
- Only when *only the host* can reach the controller does the controller's event log become a
  trustworthy audit source (combined with [[event-log-ingestion]] + the
  [[append-only-event-chain]]).

This makes the UHPPOTE setup **tamper-evident behind isolation** — but never tamper-*proof*;
that requires the [[esp32-custom-controller]].