gentoo-overlay/net-misc/ntpsec/files/ntpd-r1.service

[Unit]
Description=Network Time Service
After=network.target nss-lookup.target
Conflicts=systemd-timesyncd.service

[Service]
Type=simple
PrivateTmp=true
ExecStart=/usr/sbin/ntpd --configfile=/etc/ntp.conf --panicgate --user=ntp:ntp --nofork
# Specifying -g on the command line allows ntpd to make large adjustments to
# the clock on boot.  However, if Restart=yes is set, a malicious (or broken)
# server could send the incorrect time, trip the panic threshold, and when
# ntpd restarts, serve it the incorrect time (which would be accepted).
Restart=no
RemainAfterExit=yes

[Install]
WantedBy=multi-user.target