Bridging between network interfaces in linux

Assume I have a linux computer, ruing an OpenVPN Access Server with the following interfaces:

wwan0 - Inteet access, IP 212.179.50.50

tun0 - OpenVPN interface, IP 172.225.25.1 (the SERVER's VPN IP)

eth0 - Etheet interface, coected to a switch and gets IP 10.0.0.10 (Switch's IP is 10.0.0.1)

What I am trying to do:

1. Allowing clients to coect to the OpenVPN server using the server's public inteet IP (done that).
2. Allowing those clients who coect to the OpenVPN server, to PING the switch (10.0.0.1), and any other device coected to that switch.

What is the easy way of doing this (using ifconfig/iptables/etc).

Thanks!