IP Helper extends your abilities to manage network interfaces. There is a one-to-one correspondence between the interfaces and adapters on a given computer. An interface is an IP-level abstraction, whereas an adapter is a datalink-level abstraction.
Use the functions described in the following paragraphs to manage interfaces on the local computer.
The GetNumberOfInterfaces function returns the number of interfaces on the local computer.
The GetInterfaceInfo function returns a table that contains the names and corresponding indexes for the interfaces on the local computer. For code samples involving GetInterfaceInfo see Managing Interfaces Using GetInterfaceInfo.
The GetFriendlyIfIndex function takes an interface index and returns a backward-compatible interface index, that is, one that uses only the lower 24 bits. This type of index is sometimes referred to as a "friendly" interface index.
The GetIfEntry function returns a MIB_IFROW structure that contains information about a particular interface on the local computer. This function requires the caller to supply the index of the interface.
Use the SetIfEntry function to modify the configuration of a particular interface.