Controlling CRM ACCESS - Through IP\'s HTAccess

Hi, I am looking for someone who knows in and out of CRM's like VTiger - I want to control my CRM remotely by giving access to the IP groups or Ip's so that it will only work in that IP, or if someone access that from outside, it will be blocked , but if that person shares the IP address, I should be able to authorize that IP for particular time and Interval I am willing to pay a decent price for this job. Thank's