Ntp
NTP 無法同步或找不到合適的伺服器
我要解決的問題是 NTP 不會同步：
$ sudo ntpstat unsynchronised time server re-starting polling server every 64 s編輯：這是一些 ntpq 輸出：
$ sudo ntpq -c peers remote refid st t when poll reach delay offset jitter ============================================================================== ntp.eecs.wsu.ed .INIT. 16 u - 64 0 0.000 0.000 0.000 71.19.224.242 .INIT. 16 u - 64 0 0.000 0.000 0.000 ntp4.vps.net .INIT. 16 u - 64 0 0.000 0.000 0.000 mercury.z0p.org .INIT. 16 u - 64 0 0.000 0.000 0.000 li506-17.member .INIT. 16 u - 64 0 0.000 0.000 0.000 4.53.160.75 .INIT. 16 u - 64 0 0.000 0.000 0.000 ntp1.ResComp.Be .INIT. 16 u - 64 0 0.000 0.000 0.000我有預設的 RHEL6 /etc/ntp.conf 配置。伺服器位：
server 0.rhel.pool.ntp.org server 1.rhel.pool.ntp.org server 2.rhel.pool.ntp.org當我停止 ntpd 並嘗試手動執行 ntpdate 時，我得到所有這些伺服器的“找不到適契約步的伺服器”。這是帶有調試輸出的 ntpdate：
$ ntpdate -dq 1.rhel.pool.ntp.org 10 May 10:02:42 ntpdate[13320]: ntpdate 4.2.4p8@1.1612-o Thu May 13 14:38:25 UTC 2010 (1) Looking for host 1.rhel.pool.ntp.org and service ntp host found : caprica.willglynn.com transmit(208.88.126.226) transmit(66.225.61.66) transmit(149.20.68.17) transmit(4.53.160.75) transmit(208.88.126.226) transmit(66.225.61.66) transmit(149.20.68.17) transmit(4.53.160.75) transmit(208.88.126.226) transmit(66.225.61.66) transmit(149.20.68.17) transmit(4.53.160.75) transmit(208.88.126.226) transmit(66.225.61.66) transmit(149.20.68.17) transmit(4.53.160.75) transmit(208.88.126.226) transmit(66.225.61.66) transmit(149.20.68.17) transmit(4.53.160.75) 208.88.126.226: Server dropped: no data 66.225.61.66: Server dropped: no data 149.20.68.17: Server dropped: no data 4.53.160.75: Server dropped: no data server 208.88.126.226, port 123 stratum 0, precision 0, leap 00, trust 000 refid [208.88.126.226], delay 0.00000, dispersion 64.00000 transmitted 4, in filter 4 reference time: 00000000.00000000 Thu, Feb 7 2036 1:28:16.000 originate timestamp: 00000000.00000000 Thu, Feb 7 2036 1:28:16.000 transmit timestamp: d5377c86.25dd5f5a Fri, May 10 2013 10:02:46.147 filter delay: 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 filter offset: 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 delay 0.00000, dispersion 64.00000 offset 0.000000 server 66.225.61.66, port 123 stratum 0, precision 0, leap 00, trust 000 refid [66.225.61.66], delay 0.00000, dispersion 64.00000 transmitted 4, in filter 4 reference time: 00000000.00000000 Thu, Feb 7 2036 1:28:16.000 originate timestamp: 00000000.00000000 Thu, Feb 7 2036 1:28:16.000 transmit timestamp: d5377c86.591061f7 Fri, May 10 2013 10:02:46.347 filter delay: 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 filter offset: 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 delay 0.00000, dispersion 64.00000 offset 0.000000 server 149.20.68.17, port 123 stratum 0, precision 0, leap 00, trust 000 refid [149.20.68.17], delay 0.00000, dispersion 64.00000 transmitted 4, in filter 4 reference time: 00000000.00000000 Thu, Feb 7 2036 1:28:16.000 originate timestamp: 00000000.00000000 Thu, Feb 7 2036 1:28:16.000 transmit timestamp: d5377c86.8c427d35 Fri, May 10 2013 10:02:46.547 filter delay: 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 filter offset: 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 delay 0.00000, dispersion 64.00000 offset 0.000000 server 4.53.160.75, port 123 stratum 0, precision 0, leap 00, trust 000 refid [4.53.160.75], delay 0.00000, dispersion 64.00000 transmitted 4, in filter 4 reference time: 00000000.00000000 Thu, Feb 7 2036 1:28:16.000 originate timestamp: 00000000.00000000 Thu, Feb 7 2036 1:28:16.000 transmit timestamp: d5377c86.bf762a87 Fri, May 10 2013 10:02:46.747 filter delay: 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 filter offset: 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 delay 0.00000, dispersion 64.00000 offset 0.000000 10 May 10:02:47 ntpdate[13320]: no server suitable for synchronization found我可以 ping 池將我定向到的一些 NTP 伺服器：
$ ping caprica.willglynn.com PING caprica.willglynn.com (208.88.126.226) 56(84) bytes of data. 64 bytes from caprica.willglynn.com (208.88.126.226): icmp_seq=1 ttl=52 time=60.2 ms 64 bytes from caprica.willglynn.com (208.88.126.226): icmp_seq=2 ttl=52 time=59.6 ms 64 bytes from caprica.willglynn.com (208.88.126.226): icmp_seq=3 ttl=52 time=59.9 ms 64 bytes from caprica.willglynn.com (208.88.126.226): icmp_seq=4 ttl=52 time=59.8 ms埠 123 的網路統計：
$ netstat -ano|grep 123 udp 0 0 10.0.116.6:123 0.0.0.0:* off (0.00/0/0) udp 0 0 127.0.0.1:123 0.0.0.0:* off (0.00/0/0) udp 0 0 0.0.0.0:123 0.0.0.0:* off (0.00/0/0) udp 0 0 :::123 :::* off (0.00/0/0)iptables 和 ip6tables 已關閉，但有一個外部防火牆應該為 UDP 打開埠 123。
確保機器和網際網路的其餘部分之間沒有外部防火牆。如果有，請要求管理防火牆的人員打開埠 123。