VPN from server in green or orange network to IPFire

Hi,
is it possible to connect a server in the green or orange network to IPFire via VPN?
So are IPSec or OpenVPN connections possible at the green or orange firewall? Or is it only available on red?
Because of a special network configuration i can’t set the default route of this server to IPFire. I want to build a tunnel and set the default route to the tunnel.
Regards, Dieter