You can get an assortment of devices that receive time signals from satellites to act as good authoritative time sources on your private network if you are willing to spend some money. If you just want to fake it, I think the trick is to lower the stratum number in the 'fudge' setting in ntpd.conf.
Les
I have tried dropping the stratum to 2,1 and 0 - did notice any effect Of course doing service ntpd restart each time.
Thanks,
jerry