nginx optimization doc

Web-Servers/Nginx/09-Ratelimit.md

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+# Nginx Rate Limiting Guide
+
+Nginx can control request rates using the **Leaky Bucket algorithm**. This helps prevent abuse, protect resources, and manage traffic efficiently.
+
+---
+
+## Basic Configuration
+
+```nginx
+limit_req_zone $binary_remote_addr zone=mylimit:10m rate=1r/s;
+
+server {
+    server_name files.usethelinux.shop;
+    root /srv/files;
+
+    location / {
+        autoindex on;
+        limit_req zone=mylimit burst=4 nodelay;
+    }
+}
+```
+
+### Explanation:
+
+* `$binary_remote_addr` → Client IP Address
+* `10m` → Zone memory size (10MB) can handle approximately 160,000 addresses
+* `1r/s` → 1 request per second
+* `burst=4` → Allows a peak of 4 requests without delay
+* `nodelay` → Rejects requests immediately when the limit is exceeded
+
+> The rate can also be set lower, e.g., `10r/min` (10 requests per minute)
+
+---
+
+## Two-Stage Configuration (Smooth Bursting)
+
+```nginx
+limit_req_zone $binary_remote_addr zone=mylimit:10m rate=5r/s;
+
+server {
+    server_name files.usethelinux.shop;
+    root /srv/files;
+
+    location / {
+        autoindex on;
+        limit_req zone=mylimit burst=4 delay=2;
+    }
+}
+```
+
+### Behavior:
+
+* Requests 1–7 → Handled at full speed
+* Requests 8–9 → Handled with delay
+* Requests above 9 → Rejected
+
+---
+
+## Advanced Configuration
+
+```nginx
+limit_req_zone $binary_remote_addr zone=mylimit:10m rate=3r/s;
+
+server {
+    server_name files.usethelinux.shop;
+    root /srv/files;
+
+    location / {
+        autoindex on;
+        limit_req zone=mylimit burst=4 delay=2;
+        limit_req_status 403;
+        limit_req_log_level warn;
+    }
+
+    error_log /var/log/nginx/rate-error.log warn;
+}
+```
+
+### Additional Options:
+
+* `limit_req_status` → Status code returned when requests are rejected (e.g., 403)
+* `limit_req_log_level` → Logging level for rate-limit warnings (requires `error_log` configured)
+
+---
+
+## Whitelist Specific IPs
+
+```nginx
+geo $limit {
+    default 1;
+    10.0.0.0/8 0;
+    192.168.0.0/24 0;
+    93.127.222.112/32 0;
+}
+
+map $limit $limit_key {
+    0 "";
+    1 $binary_remote_addr;
+}
+
+limit_req_zone $limit_key zone=mylimit:10m rate=2r/s;
+
+server {
+    server_name files.usethelinux.shop;
+    root /srv/files;
+
+    location / {
+        autoindex on;
+        limit_req zone=mylimit burst=3 delay=1;
+        limit_req_status 403;
+        limit_req_log_level warn;
+    }
+
+    error_log /var/log/nginx/rate-error.log warn;
+}
+```
+
+### Explanation:
+
+* `geo` → Defines a variable with default `1` (all clients)
+* `map` → Applies `limit_req_zone` only to non-whitelisted IPs
+* Whitelisted IPs (value `0`) are not limited, others follow rate limits
+
+---
+
+## Summary
+
+* **`limit_req_zone`** → Defines the rate-limiting key and storage
+* **`limit_req`** → Applies the rate limit to a location
+* **Burst & Delay** → Control traffic spikes smoothly
+* **Whitelist** → Exclude trusted IPs from rate limiting
+* **Logging & Status** → Monitor and handle rejected requests efficiently
+
+