CentOS虚拟机静态日期自动变更致应用中断求助

Hey there, let's troubleshoot this annoying date reset issue on your CentOS VM. It's a real headache when your static date requirement gets disrupted unexpectedly—especially when it breaks your application. Let's walk through potential fixes based on what you've already tried and other common culprits:

1. Hunt Down Hidden Time Sync Services #

Even if you uninstalled NTP, CentOS (especially 7 and newer) often uses alternative time sync tools like chronyd or systemd-timesyncd by default. These could be quietly overriding your date:

• First, check if these services are running:

  systemctl status chronyd
  systemctl status systemd-timesyncd
  

• If either shows as active, stop, disable, and mask them to prevent them from starting back up:

  # For chronyd
  systemctl stop chronyd
  systemctl disable chronyd
  systemctl mask chronyd
  
  # For systemd-timesyncd (if applicable)
  systemctl stop systemd-timesyncd
  systemctl disable systemd-timesyncd
  systemctl mask systemd-timesyncd
  

2. Double-Check VMware Time Sync Settings #

You mentioned adjusting VMware sync, but let's make sure we've covered all bases here:

• On your ESXi/vSphere host, navigate to the VM's settings > Options > VMware Tools, and ensure the "Synchronize guest time with host" option is unchecked.
• Inside the VM, edit the VMware Tools config file /etc/vmware-tools/tools.conf to explicitly disable time sync:

  [timesync]
  enabled = false
  

• Restart the VMware Tools service to apply changes:

  systemctl restart vmtoolsd
  

3. Check for Unexpected Scheduled Tasks #

Your daily cron job resets the date at midnight, but another scheduled task might be running at 3 PM to change it back. Let's audit all cron-related items:

• List cron jobs for every user on the system:

  for user in $(cut -f1 -d: /etc/passwd); do crontab -u $user -l; done
  

• Check system-wide cron directories for scripts that could modify the date:

  ls -la /etc/cron.d/ /etc/cron.hourly/ /etc/cron.daily/ /etc/cron.weekly/ /etc/cron.monthly/
  

• Also, check anacron—it can run missed tasks when the VM is online, which might trigger a date change:

  anacron -t /etc/anacrontab -n
  

4. Lock Down Systemd's Timedatectl #

Ensure systemd isn't secretly syncing the time in the background:

• Run timedatectl and verify that NTP service and System clock synchronized both show no.
• If either is yes, disable NTP sync with:

  timedatectl set-ntp false
  

5. Dig Into System Logs to Find the Culprit #

Logs can tell us exactly what's changing the date at 3 PM. Let's search for relevant entries:

• For CentOS 7+, use journalctl to narrow down to the 3 PM window:

  journalctl --since "14:59:00" --until "15:01:00" | grep -i "date\|time"
  

• For older CentOS versions, check /var/log/messages:

  grep -i "date\|time" /var/log/messages | grep -B2 -A2 "Jun 23"
  

Look for entries that show a process or user executing date -s or timedatectl set-time—this will point you directly to the source.

6. Lock Date-Modifying Commands (As a Last Resort) #

To prevent any unauthorized changes, you can make the date and timedatectl commands immutable with chattr. This way, only root can modify them (and you'll need to adjust your cron job to temporarily remove the lock):

• First, apply the immutable flag:

  chattr +i /usr/bin/date
  chattr +i /usr/bin/timedatectl
  

• Update your cron job to remove the lock, set the date, then reapply the lock:

  0 0 * * * /bin/chattr -i /usr/bin/date && /bin/date -s "2017-06-23 00:00:00" && /bin/chattr +i /usr/bin/date
  

内容的提问来源于stack exchange，提问作者Santosh