What resources are best for search .onion networks within the Tor? Unlike the web where you can search for a domain or portal, what equivalent systems are available for search for Tor specific networks basically .onion networks/sites without actually knowing their address? Must you know what they are already to go to them directly or is there a master listing/search/or directory for them? Based on subject or whatnot?
I have read this questions and the answers but I am looking for a resource or method to look directly within the Tor network layers.