We have a RUTX09 connected via GSM interface and we use IPSec tunnel between GSM address of the router and our firewall in a private APN. I want to use NTP via IPSec so I need to change source IP address for NTP packets to loopback IP that it is encrypted by IPSec policy. Web GUI does not allow to influence source IP address. I suppose that default behaviour is to use IP address of outgoing interface as a source so NTP probably uses GSM address. The routing and firewall rules block access from GSM address. Is there any possibility how to set source IP address of NTP packets? Loopback IP is successfully used for ssh access and for monitoring status of the router. I want to use it for NTP too.