Modbus/TCP is an open automation protocol used in a variety of SCADA, PLC, and industrial IO applications. Modbusfw is a Linux 2.4.x Netfilter Extension that permits filtering decisions (DROP, REJECT, etc.) based on application-layer values, allowing finer-grained access control than is currently possibly by simply blocking TCP port 502.
BinarySEC is an intelligent Web application firewall designed to suppress malicious traffic on Web sites and applications. Its artificial intelligence engine learns normal traffic and blocks malicious requests with very high accuracy. BinarySEC secures against a wide range of attacks, including cross-site scripting (XSS), SQL injection, command injection, PHP includes, parameter tampering, buffer overflow, directory traversal, attack obfuscation, and more. BinarySEC for Apache includes a graphical installer and a Web-based administration interface.