Hello Mark et al,
ampd-1.0 daemon made by Marius YO2LOJ
is fast, selfcontained and easy to start.
It stores learned routes in encap format file,
ready to use any time in case of need.
My Raspberry Pi set into DMZ zone
sits behing my own router.
This is the ONLY requirement to have it working.
Best regards.
Tom - sp2lob