What VLANVerify is, and is not

VLANVerify helps you produce evidence that VLAN network segmentation actually holds in practice: a single Linux device on a trunk port creates a tagged sub-interface for every VLAN under test, sends ordinary ICMP pings and TCP connection attempts against a policy of allow/deny rules you define, and reports whether each rule HELD, was VIOLATED, or was INCONCLUSIVE.

A scan only observes reachability. It never edits switch, router or firewall configuration, and never blocks, redirects, spoofs or injects traffic; VLANVerify is a testing tool, not an enforcement one.

VLANVerify reports what it actually measured, at the moment it measured it. A scan is a point-in-time snapshot, not continuous monitoring, and its current MVP form is deliberately run-on-demand only. A configuration change made after a scan could reopen a path that held during it. Re-scan after any change to segmentation-relevant configuration.

Licence

VLANVerify is released under the MIT License.

MIT License

Copyright (c) 2026-present Stable State Consulting Ltd

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

Third-party dependencies (Click, pydantic, PyYAML, Jinja2) remain copyright of their respective authors and are subject to their own MIT/BSD-3-Clause licences; see Third-party dependencies.

Contributing

Contributions are welcome via pull requests on GitHub.

Contributions are expected to be distributed under the MIT License as part of VLANVerify.
Contributors retain copyright in their own contributions unless separately agreed in writing.
There is no Contributor Licence Agreement or copyright assignment to sign.
Add the source-file header to any new original source files: # SPDX-License-Identifier: MIT / # Copyright (c) 2026-present Stable State Consulting Ltd..
The test suite runs entirely against the dry-run/mock backends, so it needs no root privileges, no Linux, and no real network; keep new tests running that way where possible.

Scope: VLANVerify is a testing tool that only observes reachability. Please do not propose features that add traffic injection, spoofing, switch/firewall configuration changes, or any capability beyond measuring what a policy describes; such pull requests will be closed. See Scope & non-goals for what's deliberately not built yet but is welcome as a proposal.

Security & trust

Why you can trust VLANVerify and this website, what VLANVerify touches on your machine, how to verify your download, and how to report a vulnerability are all covered on the Security & trust page.

In short: report suspected vulnerabilities privately via GitHub private vulnerability reporting or email [email protected]; please do not open a public issue.

Stable State Consulting Ltd

VLANVerify is built and maintained by Stable State Consulting Ltd (www.stablestate.co.uk). For project questions, use the GitHub repository.