infrapuzzle/fritzbox/dyndns_ovh_setup.md

FritzBox OVH DynDNS (DynHost) Setup

This document describes how to configure your FritzBox to automatically update an OVH DynHost record. Since you have already set up dyndns.moritzgraf.de as a DynHost in your OVH control panel, the remaining step is to configure the FritzBox to push IP updates to OVH.

OVH DynHost Settings (Reference)

The credentials for the DynHost are securely stored in the encrypted dyndns_ovh.secret.yaml file located in this directory. Ensure you have unlocked git-crypt to view the username and password.

(Note: These are not your main OVH account credentials, but the specific credentials generated for the DynHost record!)

FritzBox Configuration Steps

1. Log into your FritzBox Web Interface (usually http://fritz.box).

2. Navigate to Internet > Permit Access > DynDNS.

3. Check the box Use DynDNS (DynDNS benutzen).

4. From the Dynamic DNS provider dropdown, select User-defined (Benutzerdefiniert).

5. Fill out the fields exactly as follows:

   • Update URL:

     https://www.ovh.com/nic/update?system=dyndns&hostname=<domain>&myip=<ipaddr>
     

     (Make sure to copy exactly as written. The FritzBox will automatically replace <domain> and <ipaddr> with the actual values.)

   • Domain name:

     dyndns.moritzgraf.de
     

   • Username: (Get the username value from dyndns_ovh.secret.yaml)

   • Password: (Get the password value from dyndns_ovh.secret.yaml)

6. Click Apply (Übernehmen) to save the settings.

Verifying the Update

After saving, the FritzBox should attempt an immediate update.

1. In the FritzBox interface, go to Overview (Übersicht).
2. Look under the Connections (Verbindungen) section. It should say: Dynamic DNS: enabled, <domain>, Status: successfully registered.
3. You can also manually ping dyndns.moritzgraf.de from an external network to verify it points to your router's current public IP.

Important Note on CGNAT and IPv6

Since your ISP uses Carrier Grade NAT (CGNAT) for IPv4, your public IPv4 address might not be directly reachable from the outside. OVH's legacy DynHost system primarily updates A (IPv4) records. If you specifically need external access to your home network via this dyndns domain, the incoming connection might fail on IPv4 due to CGNAT. (This is why we set up the Wireguard Site-to-Site VPN to the K8s cluster!)