我的 Ubuntu 上有一个功能齐全的 chrony：
v@v-VirtualBox:~$ timedatectl
Local time: Mon 2021-05-17 17:02:03 EEST
Universal time: Mon 2021-05-17 14:02:03 UTC
RTC time: Mon 2021-05-17 14:02:04
Time zone: Europe/Riga (EEST, +0300)
System clock synchronized: yes
NTP service: active
RTC in local TZ: no
v@v-VirtualBox:~$ systemctl status chrony
● chrony.service - chrony, an NTP client/server
Loaded: loaded (/lib/systemd/system/chrony.service; enabled; vendor preset: enabled)
Active: active (running) since Mon 2021-05-17 09:58:14 EEST; 7h ago
Docs: man:chronyd(8)
man:chronyc(1)
man:chrony.conf(5)
Process: 778 ExecStart=/usr/lib/systemd/scripts/chronyd-starter.sh $DAEMON_OPTS (code=exited, status=0/SUCCESS)
Process: 807 ExecStartPost=/usr/lib/chrony/chrony-helper update-daemon (code=exited, status=0/SUCCESS)
Main PID: 802 (chronyd)
Tasks: 2 (limit: 6897)
Memory: 1.9M
CGroup: /system.slice/chrony.service
├─802 /usr/sbin/chronyd -F -1
└─806 /usr/sbin/chronyd -F -1
May 17 10:22:21 v-VirtualBox chronyd[802]: Selected source 78.194.78.49
May 17 10:23:22 v-VirtualBox chronyd[802]: Source 91.189.89.198 replaced with 2001:67c:1560:8003::c8
May 17 10:27:41 v-VirtualBox chronyd[802]: Selected source 91.189.89.199
May 17 10:27:41 v-VirtualBox chronyd[802]: System clock wrong by 1119.071625 seconds, adjustment started
May 17 10:29:51 v-VirtualBox chronyd[802]: Selected source 162.159.200.123
May 17 10:53:36 v-VirtualBox chronyd[802]: Source 2001:67c:1560:8003::c8 replaced with 91.189.89.198
May 17 14:49:46 v-VirtualBox chronyd[802]: Selected source 78.194.78.49
May 17 14:52:57 v-VirtualBox chronyd[802]: Source 162.159.200.123 replaced with 151.80.168.4
May 17 15:16:23 v-VirtualBox chronyd[802]: Selected source 91.189.89.199
May 17 15:24:59 v-VirtualBox chronyd[802]: Selected source 78.194.78.49
v@v-VirtualBox:~$ chronyc sources
210 Number of sources = 8
MS Name/IP address Stratum Poll Reach LastRx Last sample
===============================================================================
^+ chilipepper.canonical.com 2 8 357 254 -2968us[-2968us] +/- 40ms
^+ pugot.canonical.com 2 9 357 991 +3907us[+3299us] +/- 41ms
^+ golem.canonical.com 2 10 377 26m -883us[-1393us] +/- 59ms
^- alphyn.canonical.com 2 9 277 26m -897us[-1399us] +/- 92ms
^+ 183-150-172-163.instance> 4 9 377 648 +2008us[+2008us] +/- 74ms
^+ net1.web.yas-online.net 3 10 377 514 +488us[ +488us] +/- 75ms
^* moz75-1-78-194-78-49.fbx> 3 9 377 664 +1298us[ +635us] +/- 30ms
^+ x.ns.gin.ntt.net 2 9 377 1169 -2448us[-3025us] +/- 73ms
然而，在使用ssh有效Kerberos票证时存在时钟偏差问题：
ssh -Xvvv ***@**.**
...
debug1: Next authentication method: gssapi-with-mic
debug1: Unspecified GSS failure. Minor code may provide more information
Clock skew too great
...
可能存在什么问题？