Multihome OpenVPN

https://community.openvpn.net/openvpn/ticket/442

Configure a multi-homed UDP server. This option can be used when OpenVPN has been con‐
figured to listen on all interfaces, and will attempt to bind client sessions to the
interface on which packets are being received, so that outgoing packets will be sent
out of the same interface. Note that this option is only relevant for UDP servers and
currently is only implemented on Linux.

Note: clients connecting to a --multihome server should always use the --nobind option.