The configuration of NTP vs timesyncd on Debian 10+ doesn’t work correctly with the 2.0.0 line of check_mk_agent. Verified in versions up to 2.0.0p39
Specifically, check_mk_agent looks for a service named ntp.service to detect the use of NTP for time configuration. In newer versions of Debian, this service is renamed to ntpsec.service.
Changing the line
if [ “$(systemctl | awk ‘/ntp.service|ntpd.service/{print $3; exit}’)” = “active” ]; then
to
if [ “$(systemctl | awk ‘/ntp.service|ntpd.service|ntpsec.service/{print $3; exit}’)” = “active” ]; then
resolves the issue.