application level

…a new generation of “application layer” firewalls emerged; though more cumbersome to set up and operate, they performed a more thorough inspection. In the early 21st century, most firewalls were hybrids of these two primary types.

…are protocols that support specific applications. An example of such an application is the file transfer protocol (FTP), which governs the transfer of files from one host to another.

The application layer is difficult to generalize, since its content is specific to each user. For example, distributed databases used in the banking and airline industries require several access and security issues to be solved at this level. Network transparency (making the physical distribution of resources…