Determines whether network access is permitted when satisfying a request.

	For example;
	    to force your neighbors to use you as a sibling instead of
	    a parent.

		acl localclients src 192.0.2.0/24 2001:DB8::a:0/64
		miss_access deny  !localclients
		miss_access allow all

	This means only your local clients are allowed to fetch relayed/MISS
	replies from the network and all other clients can only fetch cached
	objects (HITs).

	The default for this setting allows all clients who passed the
	http_access rules to relay via this proxy.

	This clause only supports fast acl types.
	See http://wiki.squid-cache.org/SquidFaq/SquidAcl for details.