Periodic update of IPs which are using Dynamic DNS (Wireguard)

[tripplet]

Hi,
I recently started using Passepartout and it works great for me so far

I would be cool if there would be an option to periodically update the IP of peers/endpoints for a Wireguard connection.
Its annoying for example when I use it to connect to my home server which is has a dynamic DNS because of the daily changing IP.
This always breaks my connection when the reconnect is happening over night.

This is some thing which is quite annoying that it is not supported on the normal Wireguard App, so this would be an awesome improvement/feature for Passepartout I think.
Thanks Tobi

[keeshux]

LOL, misclicked on the phone. I will read this tomorrow.

[keeshux]

Does this actually take a "reconnection" to break? Doesn't this systematically happen after some time? Because WireGuard is connectionless, I believe that at some point, the packets are sent to an outdated resolved IP. Whereas if a new handshake is performed, I would expect WireGuard to re-resolve the hostname and use the new IP as expected.

Please, add the steps to reproduce this consistently if you can. Thank you.

[tripplet]

In theory yes. You are right Wireguard is connectionless and will update its IPs once a new packet is seen.
The problem is that normally you are behind a NAT in your home network.
Even if you configure a keep-alive on the server side this UDP packets send to the client will be rejected by the router as the source IP has changed.
On the other side packets send by the client will be send to the wrong IP.
Due to this the wireguard kernel module will never learn of the new IP of the server.
The same applies to using it on iOS at some point the IP of the server will change, if at that point you are on your home network the same problem appears.

In summary only a reconnect of the wireguard connection on the client side helps.

For Linux there is this official script which periodically re resolves the peer IPs.
I put this into a small service for that (mostly as an exercise to learn rust 😄)

For the official windows client I also implemented this logic, see here
It was sadly never accepted, see this discussion

From my understanding this must be handled in userspace as the wireguard kernel modules have no concept of DNS/hostnames also resolving DNS in kernel space would not be ideal.