Enterprise reverse proxy: HAProxy + Nginx + WAF

Applications shouldn't handle SSL, WAF, rate limiting or load balancing directly. These are infrastructure responsibilities.

Architecture components

• HAProxy + keepalived HA
• Nginx reverse proxy
• Varnish HTTP cache
• Traefik for containers
• ModSecurity WAF
• Let's Encrypt

What we deliver

HA reverse proxy cluster, auto-renewable SSL, WAF, monitoring dashboards.

Example: Nginx reverse proxy

A minimal, ready-to-use block for an app behind Nginx with TLS:

# /etc/nginx/conf.d/app.conf — reverse proxy + TLS
server {
    listen 443 ssl;
    server_name app.example.com;
    ssl_certificate     /etc/letsencrypt/live/app.example.com/fullchain.pem;
    ssl_certificate_key /etc/letsencrypt/live/app.example.com/privkey.pem;
    location / {
        proxy_pass http://127.0.0.1:8080;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-Proto $scheme;
    }
}

HAProxy: backend with health checks

A HAProxy backend with active server health checks:

frontend web
    bind *:443 ssl crt /etc/haproxy/certs/site.pem
    default_backend app

backend app
    balance leastconn
    option httpchk GET /health
    http-check expect status 200
    server app1 10.0.0.11:8080 check inter 2s fall 3 rise 2
    server app2 10.0.0.12:8080 check inter 2s fall 3 rise 2

Nginx: rate limiting against abuse

You limit requests per IP to stop scraping and L7 attacks:

# in http {}
limit_req_zone $binary_remote_addr zone=api:10m rate=10r/s;
# in location
location /api/ {
    limit_req zone=api burst=20 nodelay;
    limit_req_status 429;
    proxy_pass http://app;
}

Nginx: cache for public content

You cache responses to reduce load on the app:

# in http {}
proxy_cache_path /var/cache/nginx levels=1:2 keys_zone=app:50m max_size=2g inactive=60m;
# in location
location / {
    proxy_cache app;
    proxy_cache_valid 200 10m;
    proxy_cache_use_stale error timeout updating;
    add_header X-Cache $upstream_cache_status;
    proxy_pass http://backend;
}

WAF: ModSecurity + OWASP CRS

You block injections and L7 attacks with a WAF:

apt -y install libnginx-mod-http-modsecurity
# activezi + OWASP Core Rule Set
git clone https://github.com/coreruleset/coreruleset /etc/nginx/owasp-crs
# nginx.conf: modsecurity on; modsecurity_rules_file /etc/nginx/modsec/main.conf;
# incepi in DetectionOnly, apoi treci pe blocking dupa tuning
nginx -t && systemctl reload nginx