[Unit]
Description=Synchronize system clock to NTP and PTP time sources
After=chronyd.service ntpd.service ntpdate.service sntp.service network-online.target
Conflicts=chronyd.service ntpd.service phc2sys.service ptp4l.service
Wants=network-online.target

[Service]
Type=simple
ExecStart=/usr/sbin/timemaster -f /etc/timemaster.conf
RuntimeDirectory=timemaster

CapabilityBoundingSet=~CAP_AUDIT_CONTROL CAP_AUDIT_READ CAP_AUDIT_WRITE
CapabilityBoundingSet=~CAP_BLOCK_SUSPEND CAP_KILL CAP_LEASE CAP_LINUX_IMMUTABLE
CapabilityBoundingSet=~CAP_MAC_ADMIN CAP_MAC_OVERRIDE CAP_MKNOD
CapabilityBoundingSet=~CAP_SYS_BOOT CAP_SYS_CHROOT CAP_SYS_MODULE CAP_SYS_PACCT
CapabilityBoundingSet=~CAP_SYS_PTRACE CAP_SYS_RAWIO CAP_SYS_TTY_CONFIG CAP_WAKE_ALARM
DeviceAllow=char-pps rw
DeviceAllow=char-ptp rw
DeviceAllow=char-rtc rw
DevicePolicy=closed
LockPersonality=yes
MemoryDenyWriteExecute=yes
PrivateTmp=yes
ProtectControlGroups=yes
ProtectHome=yes
ProtectHostname=yes
ProtectKernelLogs=yes
ProtectKernelModules=yes
ProtectKernelTunables=yes
ProtectProc=invisible
ProtectSystem=strict
ReadWritePaths=/run/timemaster /var/lib/chrony -/var/log -/var/spool
RestrictAddressFamilies=AF_INET AF_INET6 AF_NETLINK AF_PACKET AF_UNIX
RestrictNamespaces=yes
RestrictSUIDSGID=yes
SystemCallArchitectures=native
SystemCallFilter=~@cpu-emulation @debug @module @mount @obsolete @raw-io @reboot @swap

[Install]
WantedBy=multi-user.target