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DynDNS Updates without a Client

My new hosting provide Strato offers DynDNS. I was searching for a DynDNS client for my OpenSolaris Home Server, but a small bash script does the job as good as any other client.
#! /bin/bash
. ${HOME}/.dyndns.cfg
DOMAINS=$(cat ${HOME}/
echo "$(date '+%Y-%m-%d %H:%M') $(basename $0)"
for domain in ${DOMAINS}; do
        echo -n "  ${domain} - "
        curl --silent --show-error --insecure --user ${LOGIN} "${UPDATE_URL}?hostname=${domain}"

First, the login credentials (the $LOGIN variable) and the server's URL ($UPDATE_URL) are read from the config file ~/.dyndns.cfg.

Here an example config file:

UPDATE_URL="" # DynDNS service
# UPDATE_URL="" # Strato's DynDNS service

The file contains all the domains which should be updated. They must be whitespace separated, I recomment to put one domain per line.

In the for loop, curl is used to update the domains.

Currently, I use the switch –insecure to disable the SSL certificate check. As soon a I found out how to download the server certificate and check it in the correct way I will let you know in an update.

This script is part of my scripts collection, so you can find the latest version at

You can find the DynDNS protocol specification at

info/script/dyndns_updates_without_client.txt · Last modified: 2013-02-04 22:17 (external edit)