How to log NAT translation on 6.48 ?

Hello,

For compliance reasons, I need to log NAT translations occurring on a 6.48-powered CCR1009.
I need to log entries such as:
<private_src_ip> <private_src_port> <public_src_ip> <public_src_port>

If necessary, I’ve got a Debian host close to the CCR1009 where I can push log entries or files to, for further processing (insertion in database, …).
I can either pull files from this Debian host or push them from the CCR1009.

How can I proceed ?
Suggestions ?
Recent pointers ?

Best regards