IPv6 and forensic requests

Hi All, we are implementing IPv6 only infrastructure. For IPv4 access, we using tayga for 6to4 translation and then CGN for NAT. There is a number of ways for Linux based NAT to store information for future forensic requests (i.e. "who was it cracking that website?"). But what about 6to4 translators, as tayga? I believe there should be well-known patches or solutions. The aim is to have what /64 (not even /128) was translated to what IPv4 at the requested time. Is there any?