Nginx Rate Limiting on OpenBSD 7.5

Rate limiting protects your application from abuse and DDoS attacks.

Step 1 – Define a limit zone in http context

Edit /etc/nginx/nginx.conf:

http {
    # Allow 10 requests/second per IP; burst up to 20
    limit_req_zone $binary_remote_addr zone=api_limit:10m rate=10r/s;
    limit_req_zone $binary_remote_addr zone=login_limit:10m rate=5r/m;
    ...
}

Step 2 – Apply the limit to a location

server {
    ...
    location /api/ {
        limit_req zone=api_limit burst=20 nodelay;
        limit_req_status 429;
        proxy_pass http://backend;
    }

    location /login {
        limit_req zone=login_limit burst=3;
        limit_req_status 429;
        proxy_pass http://backend;
    }
}

Step 3 – Return a custom 429 error page

error_page 429 /429.html;
location = /429.html {
    root /var/www/html;
    internal;
}

Step 4 – Reload Nginx

nginx -t && systemctl reload nginx

Monitoring rate-limit hits

grep '429' /var/log/nginx/access.log | awk '{print $1}' | sort | uniq -c | sort -rn | head -20