????????OR????????????
????restrict default ignore
????restrict 172.18.65.0 mask 255.255.255.0 nomodify notrap
????#restrict [???IP] mask [netmask_IP] [parameter]
????#???? parameter ?????????е?????Щ??
????ignore?? ???????????? NTP ??????
????nomodify?? ??????????? ntpc ?? ntpq ????????????????????????????? ?????????????????????????????У????
????noquery?? ???????????? ntpq?? ntpc ??????????????????????????? NTP ??????У????
????notrap?? ???? trap ???????????? (remote event logging) ??????
????notrust?? ????????????????
????3.???????ok??????NTP??????
????172.18.65.1?????NTP????????service ntp start   ????   /etc/init.d/ntp start
????4.??????????(????Suse Linux??11?汾????????ntpdate?????????μ?sntp??????в???)
?????????????????????У?sntp -P no -r 172.18.65.1
?????????????????????????????????????
????5.????????????????????
????$crontab -e
???????????磺* 2 * * * * sntp -P no -r 172.18.65.1   #???2??С?????????????????????
????6.??NTP??????????
????$ntpq -q

????ntpq -p ?????г???????? NTP ????????? NTP ????????????????ε????????
????remote?????? NTP ?????? IP ?????????????????????
????????С? * ??????????????????е???? NTP????????????????????????????????????LOCAL(0)
?????????? + ????????????????????????????????????μ??????
????refid???ο???????? NTP ????????
????st???? stratum ??????
????when????????????????????????????μ??????
????poll??????θ?????????????
????reach?????????? NTP ???????????μ????
????delay?????紫?????????????????λ? 10^(-6) ??
????offset???????????????λ?? 10^(-3) ??
????jitter??Linux ??????? BIOS ????????????? ??λ? 10^(-6) ??
????7.????????
?????????????????????????????????????41?????????????????????????????????????????????
???????????????????????????????????????????????????????????????????????????????????????
?????????????ntpq -p???????????????????offset????????????????????????????????????????????
?????????????μ?40????????????????????????172.18.65.1???????????????????????ntpq -p?????????????????
??????????????????????ntp.conf???????????￡?
????restrict default ignore
????server 172.18.65.1 prefer  #perfer??????????Server IP ???????
????restrict 172.18.65.0 mask 255.255.255.0 nomodify notrap
????fudge  127.127.1.0 stratum 10   # LCL is unsynchronized
????#????server?趨???NTP???????????NTP?????????趨??????
????#server    [IP OR HOSTNAME]    [PREFER]
????#?????????
????#ip or hostname ?????ntp????????ip???????????
????#prefer ?? ???????????????
???????????????????￡?
????172.18.65.1?????NTP????????service ntp start   ????   /etc/init.d/ntp start
????????????????????????service ntp start

?????????????????????-0.479ms??????????????????????