iptables nat and connection tracking in multiacst router

mcaster1

I would like to understand if kernel connection tracking of does not break the nat rules in case the server is running mcast router (= flooding the packet to multiple interfaces).

Suppose you have mcast router which sees igress multicast traffic on eth0 and flooods it on eth1 .. eth10 acording to its multicast rules. Now we add some post-routing SNAT rules for each interfaces (replace the original source with the source of the interface). The issue here is that according to my understanding kernel is applying the nat rules according to connection identifier which is based on source and destination which does not change of cause - so it would always be the same rule chosen, according to igress trafffic parameters. However there's different NAT rules which must applied on each egress interfaces.

Is it kernel bug? I think the connection tracking must be suppressed automatically if host is running