How to Install ModSecurity for Nginx

Step 1: Install Dependencies

sudo apt install gcc make libpcre3-dev libssl-dev libcurl4-openssl-dev libgeoip-dev libxml2-dev libyajl-dev -y

Step 2: Download ModSecurity

git clone --depth 1 -b v3/master https://github.com/SpiderLabs/ModSecurity
cd ModSecurity
./build.sh
make
sudo make install

Step 3: Compile Nginx ModSecurity Connector

git clone https://github.com/SpiderLabs/ModSecurity-nginx.git
# Then recompile Nginx with --add-module=./ModSecurity-nginx

Step 4: Configure ModSecurity

sudo cp /etc/nginx/modsecurity.conf /etc/nginx/modsecurity.conf
sudo nano /etc/nginx/modsecurity.conf

Set:

SecRuleEngine On

Step 5: Enable in Nginx Site

server {
    modsecurity on;
    modsecurity_rules_file /etc/nginx/modsecurity.conf;
}