Administering network selection

Network selection overview

The network selection component is built around:

a network configuration database (the /etc/netconfig file) that contains entries for each network available to the system.
an optional NETPATH environment variable, set by a user or the system administrator, which contains an ordered list of network identifiers. These network identifiers match the netconfig ``network ID'' field and are used as links to the records in the netconfig file.

The network selection Application Programming Interface (API) consists of a set of network configuration database access routines. One group of these library routines accesses only the netconfig entries identified by the NETPATH environment variable; another group of routines accesses netconfig directly. The routines are described in ``Network selection''. The first group is also described in detail in getnetpath(3N). The second group is described in getnetconfig(3N).

Applications should use the routines that access NETPATH. These routines allow users to influence the selection of transports used by the application. If an application does not want the user to influence its decision, then the routines that access the netconfig database directly should be used.

The netconfig file, on which the network selection library routines depend, is maintained by the system administrator. The NETPATH environment variable is typically set or modified by application programmers and users, depending on the needs of their applications, but it may also be set by the system administrator in response to the needs of administrative applications.