CacheGuard is a Linux-based OS/appliance dedicated to Web traffic security and optimization. It transforms an x86-based machine into a powerful Web gateway appliance. It allows you to control Web traffic for Web surfers and Web servers by acting as a forwarding and reverse HTTP / HTTPS proxy. It supports HTTP transparent implementation, HTTP compression, Web caching, URL guarding, and Web server load balancing. It features a stateful firewall with NAT and PAT, and a content filtering module blocking malicious HTTP requests like XSS, SQL and Command Injection. It integrates a caching DNS, a DHCP server, a bandwidth shaper to manage the QoS, a load sharing system, and an HA (high availability) mode with VRRP and link bonding.