[ALUG] Self-hosted DDNS

Are there any free (preferably as in speech) dynamic DNS packages, to provide services similar to those offered by DynDNS? Just to be clear, I'm not looking for something like ddclient (which connects to services like DynDNS), I want to set up my own DNS server which can be updated by those types of clients. (The application is industrial hardware we're supplying as part of other solutions which will often be set up with Internet access, often with dynamic IP, and we want to keep track of them.) -- Mark Rogers // More Solutions Ltd (Peterborough Office) // 0845 45 89 555 Registered in England (0456 0902) at 13 Clarke Rd, Milton Keynes, MK1 1LG