How can I log IP addresses of all visitors to my wp-login.php page?

I am experiencing continuous brute force attempts from some IP addresses on my wordpress installation at https://www.vineeth.in. I have installed certain logging and access control add-ons but I am looking for a way in which I could log IP and time stamp of all visitors to my wp-login.php. The counter codes given by sites like StatCounter, when added to this file, generated PHP script errors.

Please help me to implement an IP logging system on my wp-login.php.