Restrict cookies to a single IP address.

src/ipc.proto

@@ -166,6 +166,7 @@ message cookie
 	required string username = 1;
 	required string groupname = 2;
 	required string hostname = 3;
+	required string ip = 4;
 	required bytes session_id = 5;
 	required uint32 expiration = 6;
 	required uint32 ipv4_seed = 7;