WireGuard within a WireGuard VPN

WireGuard within a WireGuard VPN

[Lonnie Abelbeck]

Hi,

I have successfully implemented a WAN failover using a Netgear LB1121 =
4G/LTE Modem over a WireGuard tunnel to a VM instance (static IPv4) in =
the cloud.

Since most 4G/LTE providers only support outbound-only (NAT'ed), =
IPv4-only, dynamic IPv4 address networks, by using WireGuard to a static =
IPv4 endpoint a bidirectional dual-stack IPv4/IPv6 network is created.  =
Works very well.

Question ...

When failover occurs a 0.0.0.0/1 + 128.0.0.0/1 route is added to the wg0 =
interface via the cloud VM WireGuard address.

There is a secondary WireGuard peer (dynamic remote endpoint) other than =
the failover 4G/LTE peer, which on failover tries to re-establish over =
the WireGuard failover peer, which fails.

Possible solutions:

1) On failover add a route for the secondary endpoint (extracted using =
'wg') and route to the ethernet interface the 4G/LTE Modem is connected. =
 Fingers crossed the dynamic remote endpoint does not change during the =
failover.

2) Possibly reduce the MTU of the secondary WireGuard peer to allow it =
to work within the WireGuard failover peer.  If so, what MTU would be =
required for WG to tunnel within another WG ? Possibly would require =
separate wg0 and wg1 interfaces for matching MTU's ?

Appreciate any comments.

Lonnie