In order to meet the needs of more and more users to provide server protection to the Internet, a new generation of firewalls adopt separate protection strategies to protect the external servers that users access to the Internet. It uses a network card to treat the external server as an independent network , The external server is both part of the internal network and completely isolated from the internal gateway. This is the Secure Server Network (SSN) technology, which can be managed separately from the hosts on the SSN or set up to manage from the intranet via FTP, Telnet, and more.