gjh42 is right.
If you're hoping to minimize fraud, trying to do so by logging IP address is futile. 99% of the public connects to the internet using dynamically generated IP addresses, and fraudsters do indeed spoof their IP's.
The best prevention against fraud are to:
- make sure your site and your server are as secure as possible by correctly configuring security elements and using the most up-to-date versions of zencart,
- install and configure SSL (dedicated SSL is best),
- consider using CAPTCHA scripts on mailer forms and user input submissions,
And in the commercial process...
- View different billing and shipping addresses as suspicious until proven otherwise.
- Use a proper online payment gateway for c-card transactions.
- Never store credit card data in your database.
- Do not accept online orders from people in countries you would not normally do business with. Telephone interested customers and verify their credentials.
- View your user logs daily and look for suspicious behaviours.
- Report any suspicious attempts to hack your site to your hosting service immediately.