What is application gateway?
An application gateway or application level gateway (ALG) is a firewall proxy that provides network security. It filters incoming traffic according to certain specifications, which means that only transmitted network application data is filtered. Such network applications include File Transfer Protocol (FTP), Telnet, Real-Time Streaming Protocol (RTSP), and BitTorrent.
Application gateways offer secure communication at the highest level. For example, when a client requests access to server resources such as files, web pages, and databases, the client first connects to the proxy server, which then connects to the main server.
The application gateway is located on the client and server firewall. The proxy server hides Internet Protocol (IP) addresses and other secure information on behalf of the client. A computer's internal system can communicate with an external computer using firewall protection. The application gateway and the external computer work without any client information or knowledge of the IP address of the proxy server.