Get external IP and update ddns service
I find it annoying that you can't update both the IPv4 and IPv6 records in just one invocation of your program.

According to the usage guide at https://dns.he.net,


Hurricane Electric also provides a "what is my IP address?" service, at http://checkip.dns.he.net/ .  That way, your program wouldn't be relying on a second service provider.
Better yet, this dynamic DNS service automatically infers that you want to add a DNS record that refers to your current IP address, if you omit the myip parameter.


Autodetect my IPv4/IPv6 address:
% curl -4 "http://dyn.example.com:password@dyn.dns.he.net/nic/update?hostname=dyn.example.com"
% curl -6 "http://dyn.example.com:password@dyn.dns.he.net/nic/update?hostname=dyn.example.com"