How to mark external traffic within the network?

Question

linux

There is a router (on CentOS) with 2 providers. It is configured so that Internet access can go both through isp1 and through isp2. There are forwards from 10.0.0.2 to 192.168.1.2 and from 10.10.10.2 to 192.168.1.2. if the appeal came on 10.10.10.2, it can leave after 10.0.0.2, how to eliminate this situation.

Answer 1

You need to label CONNECTIONS.
This can be done by iproute2, link to start wiki.dieg.info/iptables#kriterij_connmark + read articles about configuring gateways with balancing.

Answer 2

I don't know the correct solution.
As part of the delusion - natit (src-nat) incoming traffic on these ports, then the packet will be returned in accordance with the NAT table.