dns_update is tool for dynamic dns name, it's a dns server and dns update client. for example, you have domain name call abc.com, and you want to resolve home.abc.com to you home ip adress( your family ip address may change after you reboot your router), you should add ns type record, home.abc.com, set value is ns.abc.com(this must be domain, not a ip address), and you deploy this dns server program in ns.abc.com. after you compile this program , two program generated, call dns and dsn_update, dns is dns server , and dsn_update is update client. it currently support ipv4 only.
port this the udp port to receive client udp update, auth_key is authentication key of update command. this server must run as root, dns(udp) port is 53
you can run server as
/home/user/dns_update/dns_srv 20053 1Y8IZwoC user&
the first parameter is command port, this will receive client update command. the second parameter is authentication key the third parameter is user name, after the server run as root, the process will change it's user to user.
the param of client dsn_update ./dns_update server:port auth_key domain
in this case the command line should be:
./dns_update ns.abc.com:20053 1Y8IZwoC home.abc.com
you should add dns_update client to crontab
* * * * * /home/user/dns_update/dns_update.sh