Include "identity" in the listen{} section, so that you can do

	Include "identity" in the listen{} section, so that you can do
	things like:

DEFAULT	Server-Identity == "foo", Proxy-To-Realm := foo.com

	i.e. handle the requests differently, based on which socket
	they came in on.  It's like Packet-Dst-IP-Address, but independent
	of IPv4/IPv6 concerns, and you can have multiple sockets with
	the same identity.