I'm using dydns to name my servers. My provider is using CGN, therefore my IPv4 is almost useless. Updating my IPv4 does not make any sense and I want to skip/deactivate this, I just want to update my IPv6 (e.g. after a prefix update). Is there a way to achieve/configure this with ddclient?

  • If your ISP is using CGN, then you have a residential network, and your residential terms of service forbid running services to the public Internet. You need to get a business account.
    – Ron Maupin
    Nov 28, 2021 at 1:18

1 Answer 1


Assuming a sufficiently new Perl ddclient perhaps


Makes use of the OS interface command to find IPs, ip on Linux, others on other platforms.

My reading of the source is that it only does one address family, I think. Disabled v4 just in case. Per the template config file, IPv6 requires newer than 3.8.1.

Or, consider using a v6 only network for some hosts. Remove all (non-loopback) v4 addresses from interfaces. Implement transition methods like DNS64/NAT64 where required to connect to IPv4 hosts.

  • usev6=ip yields DEBUG: get_ipv6: using ip, ip reports <undefined>. I tried usev6=web, web=checkipv6.dyndns.com, web-skip='IP Address' and the website shows the correct IPv6, but the debug output says DEBUG: get_ipv6: using web, checkipv6.dyndns.com reports <undefined> .
    – Thomas P
    Nov 30, 2021 at 20:48
  • My mistake, ip method is static IP, as in command line option. if is probably what you want, if getting the IP of a Linux box. See edit. Dec 1, 2021 at 0:29
  • With a tiny modification to usev6=if, if=enx... the edit fixed it for me. Thank you.
    – Thomas P
    Dec 1, 2021 at 5:09

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