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https://github.com/fooinha/nginx-ssl-ja3

nginx module for SSL/TLS ja3 fingerprint.
https://github.com/fooinha/nginx-ssl-ja3

fingerprint ja3 nginx ssl tls tls-ja3-fingerprint

Last synced: 5 months ago
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nginx module for SSL/TLS ja3 fingerprint.

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# nginx-ssl-ja3

nginx module for SSL/TLS ja3 fingerprint.

## Description

This module adds to nginx the ability of new nginx variables for the TLS/SSL ja3 fingerprint.

For details about the ja3 fingerprint algorithm, check initial [project](https://github.com/salesforce/ja3).

## Configuration

### Directives

Revision 110 of chrome browser introduces TLS ClientHello extensions random permutation, which makes fingerprinting irrelevant with this browser (firefox is planning to do the same).
Using JA3_SORT_EXT cc macro during nginx configure invocation (--with-cc-opt='-DJA3_SORT_EXT') configures the module to sort TLS extensions in the JA3 string. The resulting fincgerprint is not compliant anymore with the JA3 algorithm (at this time of writing), but allow to get back effectiveness of fingerprinting.

### Variables

#### $http_ssl_ja3

The ja3 fingerprint string for a SSL connection for a HTTP server.

```
771,4865-4866-4867-49195-49199-49196-49200-52393-52392-49171-49172-156-157-47-53-10,0-23-65281-10-11-35-16-5-13-18-51-45-43-21,0-29-23-24,0
```

#### $http_ssl_ja3_hash

The ja3 fingerprint MD5 hash for a SSL connection for a HTTP server.

Example:

```
http {
server {
listen 127.0.0.1:443 ssl;
ssl_certificate cert.pem;
ssl_certificate_key rsa.key;
error_log /dev/stderr debug;
return 200 "$time_iso8601\n\n$http_user_agent\n\n$http_ssl_ja3\n\n$http_ssl_ja3_hash\n";
}
}
```

#### $stream_ssl_ja3

The ja3 fingerprint string for a SSL connection for a stream server.

#### $stream_ssl_ja3_hash

The ja3 fingerprint MD5 hash for a SSL connection for a stream server.

Example:

```
stream {
server {
listen 127.0.0.1:12345 ssl;
ssl_certificate cert.pem;
ssl_certificate_key rsa.key;
error_log /dev/stderr debug;
return "$time_iso8601\n\n$stream_ssl_ja3\n\n$stream_ssl_ja3_hash\n";
}
}
```

## Build

### Dependencies

* [OpenSSL](https://github.com/openssl) - 3.3.2 (branch openssl-3.3.2)

The master version OpenSSL is required because this module fetches the
extensions types declared at SSL/TLS Client Hello by using the new early
callback [SSL_CTX_set_client_hello_cb](https://www.openssl.org/docs/manmaster/man3/SSL_CTX_set_client_hello_cb.html).

I was unable to find a way to get these values with the current versions of
nginx and OpenSSL.

So, in order to, have the client extensions available for the fingerprint,
we also need to apply a patch to the nginx code.

If you use, for development, the [docker](#docker) supplied in this repo,
the patch is already applied. Check the Dockerfile of the dev image.

### Patches

- [nginx - save client hello extensions](patches/nginx.latest.patch)
- [openssl - more tls extensions](patches/openssl-3.extensions.patch)

### Compilation and installation

Build as a common nginx module.

```bash

# Hack/patch openssl - to include more common extensions

$ patch -p1 < /build/nginx-ssl-ja3/patches/openssl-3.extensions.patch

patching file include/openssl/tls1.h
...
patching file ssl/statem/extensions.c
...

# Hack/patch nginx

$ patch -p1 < /build/ngx_ssl_ja3/patches/nginx.latest.patch

patching file src/event/ngx_event_openssl.c
...
patching file src/event/ngx_event_openssl.h
...

# Configure

$ ./configure --add-module=/build/ngx_ssl_ja3 --with-http_ssl_module --with-stream_ssl_module --with-debug --with-stream

# Install

$ make && make install

```
## Tests

Make sure that the lib directory for nginx-tests is available in the 't' directory.

```
$ TEST_NGINX_BINARY=/usr/local/nginx/sbin/nginx prove -v
```

## Docker

Docker images and a docker compose file is available at the ./docker directory.

```
$ docker-compose up --build -d

Creating nginx-ssl-ja3

```

## Contributors

@**fooinha** - author

## Fair Warning

**THIS IS NOT PRODUCTION** ready.

So there's no guarantee of success. It most probably blow up when running in real life scenarios.