Anyway, I am thinking of replacing them with IP ones since that will get me a better picture, but I dont want to have my lan exposed on a cable outside that someone could just plug into and see everything.
All the cheap NVR's I have looked at have only had a single ethernet port, and have operated the camera over the same IP range and interface that is used to connect to the network for viewing/managing them which IMO is a bit stupid.
Is there any cheap off the shelf solution that will act as a firewall of sorts between the camera and the lan, only allowing connections to the camera to happen from the lan, and only from the DVR etc?
Other option is to get a routerboard and deal with configuring it, but that is more effort than just buying something made for the job. In addition I would like to get the cameras on the flatmates lan as well, since they will no long be able to watch them from an RF modulator on the composite camera to know when the pizza is arriving.