Please note that this is also a bug in the current ntp distribution from ntp.org, but I thought you would want to know, and perhaps fix it ...
ps: I logged this under xntp3 because you don't have a way of entering bugs for ntp. You can SEARCH for bugs in component ntp, but you'll never find any, since ntp is not listed as a valid component for ENTERING bugs.
Under xntp3, the following segment in the ntp.conf file worked: requestkey 1234 enable auth Under ntp v4, this will NOT allow the use of passwords with key "1234" unless either the "enable auth" line is removed, OR the following line is added to ntp.conf: trustedkey 1234 So, this is presumably a change in the authentication requirements for ntp v4.
According to the author of ntp (Professor David Mills of the University of Delaware), the authentication code in ntp v4 has been tighted, and this is expected behavior. Hence, it is not a bug and the resolution is to include the "trustedkey" line shown above in ntp.conf.