Code for IP harvest needed

I had a line of code in a registration form years ago. I lost access to the server while in a coma for two years. Now I'm back and need the code.

When people fill out the registration form for a Wordpress blog, the info is emailed tto me. I used to get their IP at the end of the form. I need that line of code to parse (I think that's the right terminology) their IP onto the end of their registration.