Configuring ddclient on Ubuntu Server to work with Dynu.com

First, install ddclient on your Ubuntu box:

sudo apt-get install ddclient

Then configure the ddclient:

sudo nano /etc/ddclient.conf

The contents should be similar to the following, using your username, password, domain name obviously:

# Configuration file for ddclient generated by debconf
#
# /etc/ddclient.conf
protocol=dyndns2
use=web, web=checkip.dynu.com/, web-skip='IP Address'
server=api.dynu.com
login=username
password='password'
domain.dynu.com

You can also determine the update interval by specifying the following in ddclient.conf:

# check every 60 seconds
daemon=60

Be sure to put all the parameters in the configuration file before running DDClient. You can run DDClient as /usr/sbin/ddclient -daemon 300 -syslog which ensures that it is in daemon mode.

If you think your configuration is correct, but DDClient does not work as expected, you can enable debug and verbose messages by running ddclient -daemon=0 -debug -verbose -noquiet

# ddclient configuration for Dynu
#
# /etc/ddclient.conf
daemon=60                                                    # Check every 60 seconds.
syslog=yes                                                   # Log update msgs to syslog.
mail=root                                                    # Mail all msgs to root.
mail-failure=root                                            # Mail failed update msgs to root.
pid=/var/run/ddclient.pid                                    # Record PID in file.                                      
use=web, web=checkip.dynu.com/, web-skip='IP Address'        # Get ip from server.
server=api.dynu.com                                          # IP update server.
protocol=dyndns2                        
login=myusername                                             # Your username.
password=YOURPASSWORD                                        # Password or MD5 of password.
MYDOMAIN.DYNU.COM                                            # List one or more hostnames one on each line.
#MYDOMAIN.COM