14.3 Gateway
A gateway is an intermediate node that works similarly to a proxy. The main difference is that a gateway changes one application protocol to the other protocol. The most common type of a gateway has a server part that accepts HTTP requests from clients and changes them into FTP communications as shown in the following figure:
An interesting feature of the FTP gateway is that if a user wants to display the content of a directory, the gateway finds out only the directory content as listed by the list
command of the FTP protocol. Such a directory listing is not an HTML formatted web page. However, the gateway must display this directory content to the client in a web page style. To accomplish this task, the gateway must have icons for a file, a directory, etc. With the help of these icons, the gateway creates a web page containing the directory content and it is displayed to the client. The logical result is that if you display the directory content through a proxy...