To determine your IP addres via a local ethernet device, you must specify:

dev=local

In your domain section inside the INI file.  When you specify local, ddnssync
will then figure out which operating system you're running on and do the
appropriate thing to determine your IP address.  There is only one required
parameter needed when using local address detection:

dev_name = <device name>

<device name> needs to be the name of your ethernet device as determined by
your operating system.  On Linux, this is the name of the device as defined by
the ifconfig command (usually eth0, eth1, etc. or perhaps ppp0, etc. for dialup
or DSL/PPPoE Internet connections).

On Microsoft Windows, this would be the name of the device as returned by the
ipconfig command.  It is important to get this right, otherwise ddnssync may
determine your IP address incorrectly and then consequently update your DNS
records with the wrong address.

*** NOTE ***
Though planned for the immediate future, MS Windows is currently not supported
at this time.

An example domain section that uses local detection in an INI file might look
like this:

[mydomain.com]                ; Section heading - can be anything you want
dev = local                   ; Use local network address detection
dev_name = eth0               ; Grab IP address from eth0 device
subsys = Sitelutions          ; Use the Sitelutions DDNS service
subsys_user = user@domain.com ; ID
subsys_pwd = password         ; Sitelutions password 
subsys_id = "0000001,0000002" ; List of A record IDs to update