NTP Server with no connection to the internet

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http://serverfault.com – I have a small LAN that has no connection to the internet. It consists of two ubuntu servers clustered together providing NFS services to two IP cameras. I need to synchronize the time on all the equipment. The Cameras support NTP so my plan was to run NTP on the server cluster. Can I configure NTPD to just use the system time until this project gets funding to add a 3G/4G connection? This is actually going to be harder than I thought. I'm running a heartbeat cluster with DRBD. I'm going to need to have my primary server provide NTP to the two IP cameras and the other server in the clust (HowTos)