That paper actually specifically mentions VPNs as a countermeasure to BGP attacks: Increase the diversity of node connections. The more connected an AS is, th

That paper actually specifically mentions VPNs as a countermeasure to BGP attacks: Increase the diversity of node connections. The more connected an AS is, the harder it is to attack it. We therefore encourage Bitcoin node owners to ensure they are multi-homed. Observe that even single-homed Bitcoin nodes could benefit from extra connectivity by using one or more VPN services through encrypted tunnels so that Bitcoin traffic to and from the node go through multiple and distinct ASes. Attackers that wish to deny connectivity through the tunnel would need to either know both associated IP addresses or, alternatively, disrupt all encrypted traffic to and from nodes— making the attack highly noticeable. Ham radio is another great idea. It’s a bit of a gray area, at last in the US where commercial use and encryption (but not digital signatures) is prohibited. Transmitting block headers may not strictly be against the letter of the law. The transactions themselves though probably would be. I’ve been meaning to set up a service listening on APRS-IS (http://www.aprs-is.net/ http://www.aprs-is.net/) that rebroadcasts transactions to the Bitcoin network. I don’t think such a service would violate the regulations, but users who wish to use it would be responsible for ensuring their transactions did not (if that’s even possible)