ALG Application Level Gateway
An ALG is a DPI device designed to provide security and overcome interoperability issues for a particular protocol or application. In effect, ALGs are a sophisticated type of firewall, analyzing the various fields associated with inbound or outbound traffic from a particular protocol and checking to see if contains malicious content or content that will cause an interworking problem. Numerous examples of ALGs have been developed for protocols such as SIP and HTTP.
