This Electrical Mounting Box will weatherproof the cables and make it so that you don't have to drill a 3/4 inch hole in the wall (to push the Cat5 connection into the wall). With this mounting box, you can drill a smaller hole and have all your connections inside the junction box. They will weatherproof the connectors, but you will still have access to the connections.

Also, allows you to run conduit down the wall and into your camera junction box, if drilling a hole is impossible.

The diameter is 4 inches and the conduit plug (fully tightened) is 1 inch.