We have an website with a folder that userid/password

The situtation is that is the employee area. So, when the employees log-in from the office; they do not to enter the userid/password. If they enter from some place other than the office we need them to enter the userid/password.

Can i somehow have an ip listed to not require the userid/password using the Satisfy directive apache code or??
Looks like modifying the .htaccess file is needed??

Thanks for any help or direction