I have two machines running docker. A (powerful) and B (tiny vps).

All my services are hosted at home on machine A. All dns records point to A. I want to point them to B and implement split horizon dns in my local network to still directly access A. Ideally A is no longer reachable from outside without going over B.

How can I forward requests on machine B to A over a tunnel like wireguard without loosing the source ip addresses?

I tried to get this working by creating two wireguard containers. I think I only need iptable rules on the WG container A but I am not sure. I am a bit confused about the iptable rules needed to get wireguard to properly forward the request through the tunnel.

What are your solutions for such a setup? Is there a better way to do this? I would also be glad for some keywords/existing solutions.

Additional info:

  • Ideally I would like to not leave docker.
  • Split horizon dns is no problem.
  • I have a static ipv6 and ipv4 on both machines.
  • I also have spare ipv6 subnets that I can use for intermediate routing.
  • I would like to avoid cloudflare.
  • z3braEnglish
    2•11 months ago

    Keeping the source IP intact means you’ll have troubles routing back the traffic through host B.

    Basically host A won’t be able to access the internet without going through B, which could not be what you want.

    Here’s how it works:

    On host A:

    • add a /32 route to host B public IP through your local ISP gateway (eg. 192.168.1.1)
    • setup a wireguard tunnel between A and B
    • host A: 172.17.0.1/30
    • host B: 172.17.0.2/30
    • add a default route to host B wireguard IP

    On host B:

    • setup wireguard (same config)
    • add PAT rules to the firewall so to DNAT incoming requests on the ports you need to 172.17.0.1
    • add an SNAT masquerade rule so all outbound request from 172.17.0.1 are NATed with host B public address.

    This should do what you need. However, if I may comment it out, I’d say you should give up on carrying the source IP address down to host A. This setup I described is clunky and can fail in many ways. Also I can see no benefits of doing that besides having “pretty logs” on host A. If you really need good logs, I’d suggest setting up a good reverse proxy on host B and forwarding it’s logs to a collector on host A.