Can MySource Matrix restrict access based on IP?
It can in 3.6 using the new Group Membership Restrictions.
Basically, you put uses (including the new public user asset) into groups, and then conditionaly restrict their membershiup based on their IP address.
For example, grant access to a page (or site) for the Members user group. Then put the public user into this group but set a restriction that they must come from an IP address.
Then any non-logged in users from that IP address will be in the Members group, but non-logged in users from other IP address are not in the group and so do not see the content.