I have a PHP Application, hosted on IIS 7 Server.
The Application needs to be secure for a customer (based in Germany).
The problem I face is that the only security I have used is cookies.
Their solution would be to use some sort of IP Address based security, where only access from certain IP Addresses would be permitted.
The problem I see with this is that the customer has numerous different 'sites' across Germany, which would have their own servers and therefore different IP Addresses and in some cases, no server at all.
So my questions are:
1. Is IP Address security a viable option?
2. Would the customer's request be a valid concern?
3. What would be the best practice of implementing the request?