ddclient
ddclient updates dynamic DNS entries for accounts
...The client can discover your current address via network interfaces or external check services, which is crucial for NAT’d home connections. It runs as a daemon or from cron, with configurable intervals, SSL/TLS for provider communication, and robust logging to aid troubleshooting. A single configuration file defines multiple hosts, credentials, and per-record options, making complex setups straightforward. In practice, ddclient turns dynamic residential or small-office internet links into stable hostnames for VPNs, home labs, and self-hosted services.