network-interface-list

network-interface-list is a built-in function in `C source code'.

(network-interface-list)

Return an alist of all network interfaces and their network address.
Each element is a cons, the car of which is a string containing the
interface name, and the cdr is the network address in internal
format; see the description of ADDRESS in `make-network-process'.

If the information is not available, return nil.