Awesome
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.
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 - 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.
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 supplied in this repo, the patch is already applied. Check the Dockerfile of the dev image.
Patches
Compilation and installation
Build as a common nginx module.
# 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.