Layer 7 DDoS Mitigation for Nginx

This is a simple mitigation setup for using Lua with Nginx. The way this works is by acting as a reverse TCP proxy, and performing a JavaScript check for clients that are not whitelisted. By doing this, one can easily drop clients that do not support JavaScript (i.e. bots or other unwanted types of requests).

The implementation is quite similar to the service Blazingfast.io offers, and has been based on the public repository ngx_lua_anticc.

The current validation page is based on Blazingfast.io's implementation with minor modifications. You may adjust as you please.

Installation instructions

Create a working directory for installations from source files (Optional)

sudo mkdir /source
sudo chown -R <user:group> /source
cd /source

1. Download and install all dependencies

sudo apt-get install libpcre3-dev zlib1g-dev libssl-dev gcc make automake

Download and install OpenResty's LuaJIT2

wget https://github.com/openresty/luajit2/archive/v2.0.5.tar.gz
tar -xvf v2.0.5.tar.gz
cd luajit2-2.0.5/
make PREFIX=/usr/local/lib/lua
sudo make install

Download Nginx Development Kit

wget https://github.com/simplresty/ngx_devel_kit/archive/v0.3.1rc1.tar.gz
tar -xvf v0.3.1rc1.tar.gz

Download Nginx Lua Module

wget https://github.com/openresty/lua-nginx-module/archive/v0.10.14rc3.tar.gz
tar -xvf v0.10.14rc3.tar.gz

Update links, Download and install the lateset stable release of Nginx.

sudo ldconfig
wget https://nginx.org/download/nginx-1.14.2.tar.gz
tar -xvf nginx-1.14.2.tar.gz
cd nginx-1.14.2/

./configure --prefix=/usr/local/nginx --with-http_ssl_module --with-http_stub_status_module --with-ld-opt=-Wl,-rpath,/usr/local/lib/lua --add-module=/source/ngx_devel_kit-0.3.1rc1 --add-module=/source/lua-nginx-module-0.10.14rc3 --with-openssl-opt=enable-ec_nistp_64_gcc_128 --with-openssl-opt=no-nextprotoneg --with-openssl-opt=no-weak-ssl-ciphers --with-openssl-opt=no-ssl3

make
sudo make install

2. Configure Nginx to use l7_mitigation_nginx

Download the latest version of l7_mitigation_nginx

1. Unzip the archive to the Nginx conf directory.

2. Include the line include l7_mitigation_nginx-master/main.conf; in the http section of nginx.conf.

3. Restart nginx

Once you restart Nginx, the Layer 7 DDoS Mitigation will be enabled, and you will now get a validation page prior to accessing your website where the JavaScript check will be performed.

sudo killall -9 nginx
sudo ./nginx

Notes

This is a simple implementation, and bugs may occur. Feel free to use this implementation for further development, but if you do remember to give credits to https://github.com/leeyiw/ngx_lua_anticc and Blazingfast.io.