Abstract

Low-level network services are provided by network-service-provider plugins. These plugins are controlled by an extensible service provider that is layered above the TCP layer but below the Winsock-2 library and API. The extensible service provider orders the plugins based on the function performed by each plugin and on ordering hints. Plugins that redirect the protocol or socket are executed first. Plugins that examine packets or block entire packets are executed before plugins that modify packets. Plugins that compress or encrypt data are executed last for outgoing packets. Ordering hints cause a plugin to be executed before or after others in its functional class. Ordering allows examining plugins that simply read data get to the packets before an encrypting or compressing plugin renders the data unreadable. The extensible service provider has a plugin manager that orders and controls execution of the plugins. A filter manager evaluates one or more packet-filters. Filters are bound to plugins by binding objects; each socket has its own binding list of filters and plugins. Execution of some plugins can be skipped when filters bound to them do not match packets sent or received. Well-ordered plugins transparently provide a variety of network services such as content-filtering and blocking, encryption and compression, and statistics-gathering.