Web service for Dynamic DNS service

Last in my small series about running your own Dynamic DNS service: how to support clients which can’t use the nsupdate tool directly.

Required:

• A webserver with a scripting language
• A dumb client which a browser or browser emulation (like lynx or curl)

On the server side you need a little script, plus the dns-update.pl from this posting plus the Bind key for the zone you want to update. Here is the script, let’s say the name is update-zone.php:

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<?php

if ($_GET['key'] == 'cryptic_key') {
    system("/srv/www/updates.domain/dns-update.pl /srv/www/updates.domain/entry1-transfer.key entry1.updates.domain " . $_SERVER['REMOTE_ADDR']);
}

?>

The cryptic_key should be a random value, it’s only required to identify the client. Then the dns-update.pl script is executed with the Bind key, the hostname which should be updated and the IP address of the client. Note: if you want the client to supply it’s name as well (the second parameter), make sure you sanitize the input.

Now all the client has to do is open a website from time to time:

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lynx -source -dump 'http://<webserver>/update-zone.php?key=cryptic_key'

It’s a good idea to protect the website with https as well.