In this example the Domain is test.dyn.julian-lemmerich.de
and the password is MbSI4A0EsnxBcvWevVtF
curl -6 "https://test.dyn.julian-lemmerich.de:MbSI4A0EsnxBcvWevVtF@dyn.dns.he.net/nic/update?hostname=test.dyn.julian-lemmerich.de" curl -4 "https://test.dyn.julian-lemmerich.de:MbSI4A0EsnxBcvWevVtF@dyn.dns.he.net/nic/update?hostname=test.dyn.julian-lemmerich.de"
This is an example of how to implement it with cron.
# DynDNS Update every 5 minutes */5 * * * * curl -6 "https://test.dyn.julian-lemmerich.de:MbSI4A0EsnxBcvWevVtF@dyn.dns.he.net/nic/update?hostname=test.dyn.julian-lemmerich.de" */5 * * * * curl -4 "https://test.dyn.julian-lemmerich.de:MbSI4A0EsnxBcvWevVtF@dyn.dns.he.net/nic/update?hostname=test.dyn.julian-lemmerich.de"