Route internet traffic to another site

RouterOS General
1

Hello

I’ve this setup and don’t know how to achieve my target.
I’ve 3 routers (Router A, B, & C) in different locations connected through a VPN connection over Internet to a centralized router.
I’ve OSPF lmplemented so any device of one site is able to ping and see any devices of another site.

I want to make Internet traffic from PCs behind Router A going out through Router C.

I’ve done several tries but i don’t know how to do it.

any clue ?

thanks for your support
Routing.jpg

2

What kind of VPN protocol do you use to connect Router A to Router C? IPSec in tunnel mode or something else with an EoIP or some other kind of tunnel over it?