Proxmox with a FreeBSD guest
Proxmox recommends using ntpd daemon in a FreeBSD client to maintain client real time synchronization. See pve.proxmox. com/wiki/FreeBSD_Guest_Notes and forum.proxmox. com/threads/time-drift-in-windows-7-guest.41268/#post-198848
Real time is set in the guest when it first starts. After which the guest clock drifts with the hosts processor crystal.
ntpd is the ntp daemon. See www.freebsd. org/cgi/man.cgi?query=ntpd&apropos=0&sektion=8&manpath=FreeBSD+12.2-stable&arch=default&format=html
Configured via /etc/ntp.conf
Command line interface ntpq See www.freebsd. org/cgi/man.cgi?query=ntpq&sektion=8&apropos=0&manpath=FreeBSD+12.2-RELEASE+and+Ports
11 minute hardware real time clock update can be enable by adding the line "SYNC_HWCLOCK=yes" to /etc/sysconfig/ntpdate
date gives time of day to 1 second resolution
Qemu guest agent
I think qemu can also sync time between the guest and Porxmox host.
Doing so is suggested github. com/aborche/qemu-guest-agent/blob/master/supported_command_reference.md
Other virtualization systems such as vmware have time synchronization between host and guest via the agent
Time synchronization should be done via only one system otherwise interaction between them decreases time system accuracy. Which mean if an agent and ntpd is used then there would need to be a way of disabling time synchronization via the agent. I'm not sure how to do this.
pfsense guest on Proxmox host
Given it is probably best to run ntp (chrony) on Proxmox then synch time in pfsense to the Proxmox host via ntpd over the LAN interface. Ideally I would like to do the following but not sure how to acheive that in pfsense
Enable ntpd on pfsense but not listening to clients on any interface. Selecting no interfaces in the GUI does the reverse.
Disable hardware real time clock update by pfsense. This is done every 11 minutes by chronyd on the Proxmox host. In pfsense the directory structure is different, so I can't goto to /etc/sysconfig/ntpdate and set SYNC_HWCLOCK=no