NGINX JA4 Module

The module source is taken from darksail-ai, it was taken from https://github.com/darksail-ai/nginx/tree/darksail-mod/module), it has not been modified at time of writing this. 15 Dec 2023

The module is added to nginx via -add-module configure arg.

Patching NGINX to use JA4 Module

This fork contains a branch ja4 which applies a patch to use the module. The original patch is from darksail-ai, but its been modified to fix a deathloop:

Generally patches are long lived, but if there are changes in the same areas as the JA4 patch touches in vanilla nginx, then you would see chunks failing to apply. And would need to re-integrate these.

Forward Porting

Forward porting is the act of taking a feature implementation for a older version of software, and re-applying it to a future version, and resolving conflicts.

Here is a overview of how to achieve this.

export NGINX_CURRENT_VERSION=1.21.4
export NGINX_UPGRADE_VERSION=1.25.3
git clone https://github.com/unixunion/nginx.git
cd nginx
git checkout ja4-${NGINX_CURRENT_VERSION}
git remote add upstream https://github.com/nginx/nginx.git
git fetch upstream --tags
git pull upstream release-${NGINX_UPGRADE_VERSION}
git add src/event/ngx_event_openssl.c                                                                                                  git:ja4-1.21.4*
git add src/event/ngx_event_openssl.h                                                                                                  git:ja4-1.21.4*
git add src/http/modules/ngx_http_ssl_module.c

Now resolve any issues in the patching if required.

Generate the Patch

git diff release-${NGINX_UPGRADE_VERSION} | tee ja4.patch

Using the Patch

Simply apply the patch with the patch commandnginx