🔎 Fingerproxy 🔒

Fingerprints can be used for bot detection, DDoS mitigation, client identification, etc. To use these fingerprints, just extract the HTTP request headers in your backend apps.

Fingerproxy is also a Go library, which allows users implementing their own fingerprinting algorithm.

Usage

Tip

Try fingerproxy in 1 minute:

First of all, run the following commands:

make prepare
make run-test

We are ready to go. Send an HTTPS request to fingerproxy:

curl "https://localhost:8443/anything" --insecure | jq

You will see fingerprints in request headers:

{
  "args": {},
  "headers": {
    "Accept": [
      "*/*"
    ],
    "Accept-Encoding": [
      "gzip"
    ],
    "Host": [
      "httpbin.io"
    ],
    "User-Agent": [
      "curl/8.9.1"
    ],
    "X-Forwarded-For": [
      "::1"
    ],
    "X-Forwarded-Host": [
      "localhost:8443"
    ],
    "X-Forwarded-Proto": [
      "https"
    ],
    "X-Http2-Fingerprint": [
      "3:100;4:10485760;2:0|1048510465|0|m,s,a,p" // Akamai HTTP2 fingerprint
    ],
    "X-Ja3-Fingerprint": [
      "1ee96c96da0a44dc79c063f3d88105f5" // JA3 fingerprint with shorted cipher suites
    ],
    "X-Ja4-Fingerprint": [
      "t13d3613h2_018971650b2c_03eb65375a95" // JA4 fingerprint
    ]
  },
  "method": "GET",
  "origin": "::1",
  "url": "https://httpbin.io/anything",
  "data": "",
  "files": {},
  "form": {},
  "json": null
}

Production-Ready

The fingerproxy binary is production-ready. Subscan.io has 12 fingerproxy instances running in the production environment, which process almost 40,000,000 requests/day on average.

Unit tests, memory usage tests, E2E tests, and benchmarks have been implemented and run on GitHub Actions.

And of course, fingerproxy follows SemVer.

Implement Your Fingerprinting Algorithm

Check out the examples ja3-raw or my-fingerprint. No code fork needed.

Chrome JA3 Fingerprints Change Every Time

Yes, it is an known issue of the original JA3 implementation. See Google Chrome TLS extension permutation. Sorting the TLS extension is one method to avoid the affect of this feature. Here is an example ja3-sorted-extensions.

Use as a Library

Fingerproxy is degigned to be highly customizable. It is separated into serveral packages. You can find all packages in the pkg dir and use them to build your own fingerprinting server.

Here is an example echo-server. Instead of forwarding HTTP requests, it simply responds back to client with the fingerprints.

References

• JA3 fingerprint: https://github.com/salesforce/ja3
• JA4 fingerprint: https://github.com/FoxIO-LLC/ja4/blob/main/technical_details/JA4.md
• Akamai HTTP2 fingerprinting: https://www.blackhat.com/docs/eu-17/materials/eu-17-Shuster-Passive-Fingerprinting-Of-HTTP2-Clients-wp.pdf