How to deny access from an IP address to your web site
To deny access from an IP address use Allow and Deny directives in your .htaccess file. For example, to deny access from 12.345.6.789 and 98.765.4.321
order allow,deny deny from 12.345.6.789 deny from 98.765.4.321 allow from all
How to find the IP address of a website?
Use the ping command.
How to find the domain owner and host of a website?
If you are on Linux or any other *nix, It is just a matter of using whois command. For example, whois example.com
Or you can just use domain tools site or any domain registrar site.
You will get the owner name by doing a whois on the domain name and host information by doing a whois on IP address of the web site.