ndyndns is a GPL'ed update client written in C that supports custom, static, and dynamic DNS. It avoids unnecessary updates, reports errors, logs to syslog, and generally ought to be compliant with everything required for a proper dyndns client. It is written to be secure and supports running as an unprivileged process in a chroot jail. SSL-encrypted transfers are also supported.

ndyndns is dependent on cURL and currently works on Linux and the BSDs, but is easily portable to other POSIX platforms.