Abstract: The present invention, generally speaking, provides a firewall that achieves maximum network security and maximum user convenience. The firewall employs “envoys” that exhibit the security robustness of prior-art proxies and the transparency and ease-of-use of prior-art packet filters, combining the best of both worlds. No traffic can pass through the firewall unless the firewall has established an envoy for that traffic. Both connection-oriented (e.g., TCP) and connectionless (e.g., UDP-based) services may be handled using envoys. Establishment of an envoy may be subjected to a myriad of tests to “qualify” the user, the requested communication, or both. Therefore, a high level of security may be achieved. The usual added burden of prior-art proxy systems is avoided in such a way as to achieve full transparency—the user can use standard applications and need not even know of the existence of the firewall.

Abstract: The present invention, generally speaking, provides a firewall that achieves maximum network security and maximum user convenience. The firewall employs "envoys" that exhibit the security robustness of prior-art proxies and the transparency and ease-of-use of prior-art packet filters, combining the best of both worlds. No traffic can pass through the firewall unless the firewall has established an envoy for that traffic. Both connection-oriented (e.g., TCP) and connectionless (e.g., UDP-based) services may be handled using envoys. Establishment of an envoy may be subjected to a myriad of tests to "qualify" the user, the requested communication, or both. Therefore, a high level of security may be achieved. The usual added burden of prior-art proxy systems is avoided in such a way as to achieve fall transparency-the user can use standard applications and need not even know of the existence of the firewall. To achieve full transparency, the firewall is configured as two or more sets of virtual hosts.

Abstract: A Web server is provided having a multi-homed, modular framework. The modular framework allows extensions to the Web server to be easily compiled into the Web server, allowing the extensions to run natively as part of the server instead of incurring the overhead typical of CGI scripts, for example. The multi-homing capabilities of the Web server provide the appearance to Web users of multiple distinct and independent servers, allowing a small company or individual to create the same kind of Web presence enjoyed by larger companies. In effect, multiple virtual servers run on the same physical machine. The Web server as a whole is easily extensible to allow additional capabilities to be provided natively within the Web server itself. Furthermore, each virtual server is independently configurable in order to turn different capabilities on or off or to modify operation of the virtual server.

Abstract: Providing a firewall for isolating network elements from a publicly accessible network to which such network elements are attached. The firewall operates on a stand alone computer connected between the public network and the network elements to be protected such that all access to the protected network elements must go through the firewall. The firewall application running on the stand alone computer is preferably the only application running on that machine. The application includes a variety of proxy agents that are specifically assigned to an incoming request in accordance with the service protocol (i.e., port number) indicated in the incoming access request. An assigned proxy agent verifies the authority of an incoming request to access a network element indicated in the request. Once verified, the proxy agent completes the connection to the protected network element on behalf of the source of the incoming request.