lua-resty-waf

lua-resty-waf is a web application firewall implemented in Lua for OpenResty/NGINX, designed to run inline at the edge with low overhead. It inspects requests and responses during NGINX phases, applying rule logic and anomaly scoring to detect patterns like SQL injection, cross-site scripting, and protocol abuse. Rules are organized into policies with configurable actions—block, log, or allow—and can leverage shared dictionaries for counters, rate limits, and caching decisions. Because it runs inside the NGINX event loop, it scales with the web tier and avoids the latency of external proxies. Operators can extend it with custom Lua code, integrate threat feeds, or adapt it to application-specific quirks without recompiling modules. The result is a flexible, scriptable WAF that pairs the performance of NGINX with the expressiveness of Lua for nuanced HTTP defense.