On Sat, 29 Jan 2000, Ed Cogburn wrote: > Henrique M Holschuh wrote: > > ntpdate is used to do a "one time only" update to your clock. ntp is used to > > discipline your clock and will in fact keep the RTC in a short leash > > updating it every 11 minutes. > > I don't believe ntp is what Patrick needs. "ntp" is the daemon, i.e.
Yes, I agree. Patrick, try ntpdate first. It is much easier, and it demands far less configuration. Read the bottom of this message for a fast server select method and install guide. > the server. "ntpdate" is the "client software". I think what Patrick Well, ntpdate is a client-only software. ntp contains ntpd, the timekeeping daemon, which is both a server and a client. ntpdc, ntpq and others are client-only as well (and are included in the ntp package). But this is just a detail anyway ;-) > elsewhere in ntpdate or ntp-doc packages). For most of us, we should > access a secondary server, there is no reason for an "end-user" like > us to be using primary servers. I seem to remember also that some Unless you're less than 100ms away and serving time yourself to about 100 machines, using a proper configured ntp server, you have *no* business contacting a primary (stratum 1) time server. Actually, an end-user should have no business contacting public stratum 2 servers either, they should use their ISP's timeservers. But not many ISPs are this high-quality to offer timekeeping services... At the very least their backbone providers should have *good* ntp servers open to anyone in their net segment (which includes the ISP users), but not even this is true. > primary servers require "permission to access" first. Get to that Most secondary servers *do require permission to acess* as well. Only they don't feel the need to packet-filter everybody else on a show of faith that you will ask permission first. Start abusing and that won't last long. > list, write down 3-4 of the secondary servers that are geographically > close, and plug that info into ntpdate's config file. *NO*. At the very least ping them and discard the ones which are too far. ntpdate will hammer every server you tell it about with 4 to 8 request packets, causing "load" bursts on the server and you have no business doing that to 3 or 4 servers just because you're too lazy to do it right. Either use only *one* server for ntpdate, or select two (if you think two is not enough for ntpdate, either you'd better study the ntp docs and go install ntp instead, or you have a severely fucked up network connectivity). Here is a possible method to doing the server selection for ntpdate: First select a bunch (5 to 10) servers from the stratum-2 file from www.ntp.org. Pay special attention to the "use policy", and geographic location (actually, network location, but closer geographically _usually_ means closer network-wise). You'll notice most administrators request you to at the very least tell them you'll be using their servers. Now ping the servers you selected. Drop any which has average ping times above 300ms, they won't be useful. If all of them have ping times above 300ms, select the two with the lowest packet drop ratio. Servers with ping times above 800ms are useless. Drop any servers which lost too many 'ping' packets, ntp/ntpdate uses UDP and won't work well with high packet loss (actually one shoud use ntpq instead of ping to do this right, but that requires you to understand the ntpq output). Get the two best servers (lowest ping time) which aren't in the same network domain (if possible). Remember to email them request permission for usage if their entry in the stratum-2 file tells you to do so. Edit /etc/init.d/ntpdate and add the server(s) you selected. Remove hwcloch --adjust calls in /etc/init.d/hwclock.sh because it will bite you sooner or later. -- "One disk to rule them all, One disk to find them. One disk to bring them all and in the darkness grind them. In the Land of Redmond where the shadows lie." -- The Silicon Valley Tarot Henrique Holschuh
