I'm trying to build the following network architecture:
Where clients try to connect to a backend server (e.g. SSH) by using a Public Anycast IP adddress (1.2.3.4), that routes the client to the closest entrypoint.
There are 2 entrypoints:
Entrypoint 1 in London, with Public IP 3.3.3.3, which receives the traffic from clients in Europe. Entrypoint 2 in Sao Paulo, with Public IP 2.2.2.2, which receives traffic from clients in America. These 2 entrypoints have an established GRE tunnel to the backend server.
So far this works fine if the backend SSH server binds to a specific GRE tunnel interface IP, but then only clients coming from the associated entrypoint GRE address interface can connect.
How can I make so that clients can connect from both entrypoint, i.e. make the backend SSH server "bind" to both GRE interfaces and route the traffic approprietaly depending from which tunnel it came?
Thank you.