The IPv6 Web Resource Chceker (webres6) is a small tool to check IPv6-only readiness of a Web page or app. It loads a given URL using Selenium and displays the IP addresses of all hosts it fetches resources from. It comes with a CLI and Web app.
A pubic demo system is available at webres6.dev.sap.
The tool is inspired by Paul Marks' IPvFoo browser extension. While IPvFoo is more flexible and interactive, Webres6 can be run as a service and allows IPv6-only testing without installation or IPv6 on the users' client as well as automated analysis.
- Fetches a web site/app using Selenium and extracts host names and IP addresses from the performance log.
- Shows IPv4 and IPv6 addresses for all hosts used and whether the website is ready for IPv6-only clients.
- Can take screenshots from the pages crawled for debugging purpose.
- Can add WHOIS data to provide a hint about the infrastructure behind the resources.
- Can load Chrome extensions to manage cookie consent
- Can handle NAT64 on the API server side.
- Exports data using a REST API as JSON for further analysis.
- Allows caching and archiving of results in Redis or flat files.
- Calculates scores based on the share of resources available for IPv6-only clients and keeps a score-board of the results.
The tool can be accessed using a CLI Client and a built-in Web app.
Only works if Selenium is running on a dual-stack hosts (or on an IPv6-only host with NAT64).
- If the host is IPv4-only, everything will be reported in red even if the Web pages are IPv6 ready – This limitation is going to stay.
- If the host is IPv6-only without NAT64, all IPv4-only resources are missed out.
No auto-detection of NAT64 prefixes - prefixes other than the well-known prefix 64:ff9b::/96 need to be statically configured.
The Selenium automation is quite simple and just loads the URL. As modern Web pages tend to be complex, this will most likely result in many resources not getting loaded/analyzed a normal browser would load.
- No efforts are taken to hide this being a robot
- No delayed on-scroll content loading takes place
- Limited Cookie consent interactions are supported through plugins. This does not work well in practice though.
- Because we don't have long-term cooke state, we expect that some advertisements and analytics may not be loaded.
- No authentication/login takes place
Without dnsprobe, it ignores DNS aspects: Even if this tool reports green, it is still necessary to check the whole DNS delegation chain of all hosts involved for IPv6-only realness. With the dnsprobe microservice included in the project, DNS testing can be little fragile, especially in containerized environments. If the tool reports a problem, a more thorough DNS IPv6-only analysis with a tool like ready.chair6.net is recommended.
- Python 3.7+
- Flask 3.1.2+
- Selenium 4.33+ with ChromeDriver and Python support
- A dual-stack or IPv6-only host with NAT64 connectivity to run Selenium on
- Python 3.7+
- URLib3 2.5.0+ with URLlib3-future 2.13.906+
- jquery-3.7.1
- 72 web font
- libunbound with python bindings
- Flask 3.1.2+
- A dual-stack or IPv6-only host with clean outbound DNS connectivity / no DNS mingling
First, you need to have Selenium installed or
available as a service and have SELENIUM_REMOTE_URL environment variable pointing to it.
Run the following script to build virtualenvs for API and CLI: bash create-virtualenvs.sh
The api, cli, viewer and dnsprobe code can be found in the respective folders.
For api and cli, run bash source .venv/bin/activate within the respective folder before trying to execute the python code.
The viewer is also served from the api development environment.
The dnsprobe is a little more tricky, it is strongly recommend running it in docker or a debian based VM with Debian Trixie and Debian managed python. Please see the Dockerfile in the dnsprobe folder for the package dependencies.
bash docker-compose build should build the containers for the APi server and an NGNIX container serving the Web app.
bash docker-compose up launches a demo environment with Selenium deployed in a separate docker container. Please note that this only works properly if your docker setup supports IPv6, which is still challenging (especially on MacOS).
There is a helm chart available in the helm directory with a deployment example in the deploy folder.
# Start web service
./webres6-server.py [options]
Options:
-h, --help Show this help message and exit
--port PORT Port to listen on (default: 6400)
--debug Enable debugging output
Environment variables:
ADMIN_API_KEY API Key to call privileged functions
TIMEOUT Maximum timeout value in seconds
NAT64_PREFIXES Comma-separated list of NAT64 prefixes
SELENIUM_REMOTE_URL Use remote Selenium server instead of starting selenium for each request
DNSPROBE_API_URL Enable DNS checking using specified dns probe service
REDIS_URL URL for optional REDIS cache
LOCAL_CACHE_DIR DIR for optional LOCAL filesystem-based cache
ENABLE_WHOIS Enable clients to request whois lookups
WHOIS_CACHE_TTL Expiry time for whois cache
RESULT_CACHE_TTL Expiry time for result cache
RESULT_ARCHIVE_TTL Expiry time for result archive
API endpoints:
/ping liveness probe endpoint
/favicon.EXT send favicon
/res6/$metadata get OData metadata document
/res6/srvconfig list available extensions, screenshot-modes, whois support, ...
/res6/url(URL) get JSON results for URL provided
/metrics Prometheus compatible metrics
/adm/whois/expire expire old whois cache entries (requires ADMIN_API_KEY if set)
/[#URL] Web app to initiate analysis and display results./webres6-cli.py [options] URL
Options:
-h, --help Show this help message and exit
--api API Base API endpoint overriding WEBRES6_API_URL env
--srvconfig Show server configuration - incl. supported extensions and screenshot modes - and exit
-r, --read-json FILE.json Read JSON input from file ignoring URL argument
-o, --save-json FILE.json Save JSON output to file
-w, --wait WAIT Wait time for page settle (seconds)
-t, --timeout TIMEOUT Timeout for page load (seconds)
-e, --extension EXTENSION Extension to use (must be available on server)
-s, --screenshot MODE Request a screenshot from the server (default: none)
-S, --display-screenshot Display screenshot in terminal (implies --screenshot)
-m, --hide-proto Hide protocol columns
-a, --show-asn Show AS Number column
-A, --show-asd Show AS Description column
-n, --show-network Show whois network name
-q, --quiet Do not print the host list to stdout
Environment variables:
WEBRES6_API_URL Override the default API endpoint
Exit codes:
0 - Success: All hosts are IPv6-only
1 - At least one host has an IPv4 address
2 - Error occurred (see stderr)This project is open to feature requests/suggestions, bug reports etc. via GitHub issues. Contribution and feedback are encouraged and always welcome. For more information about how to contribute, the project structure, as well as additional contribution information, see our Contribution Guidelines.
If you find any bug that may be a security problem, please follow our instructions at in our security policy on how to report it. Please do not create GitHub issues for security-related doubts or problems.
We as members, contributors, and leaders pledge to make participation in our community a harassment-free experience for everyone. By participating in this project, you agree to abide by its Code of Conduct at all times.
Copyright 2025 SAP SE or an SAP affiliate company and webres6 contributors. Please see our LICENSE for copyright and license information. Detailed information including third-party components and their licensing/copyright information is available via the REUSE tool.