The specific idea is to tie a user to a specific IP address. At login time set a cookie with the IP address of the user and then check it against the address from which it is being sent from at every authentication process. To be explicit - I do want the authentication to fail if I use my laptop to login via a WiFi in a coffee shop and then try to continue working with my internet connection at home.
On the face of it, it seems like
wp_validate_auth_cookie is the place into which to add the additional check, but it doesn't provide any useful filter. I guess I can override that function but this will be my last resort, does anyone have a cleaner ideas on how to accomplish it?