Web site Iframe To other website

Hi there, good day,

I m try to archieve the following scenario

There are User(U), website A (A), website B (B)

Condition:
B is block from outside world and only allow access from A.
A is open to all.
U must access A in order to view page from B.
Must be done on web and not Remote Desktop to into A

Result: A is acting like a vpn mechanism so that A is able to view B

Current:
I create a page using iframe at A linking to B.
However, B still detect the call is from U and blocking the page from viewed.

How can i make the Iframe(or other method) from U to simulate call from A to B?

Please help...

Thanks in advanced

edited**
A is using PHP
B is using ASPNET

I'm pretty sure you're going to have to look into passing credentials from the php page to the aspnet page.

Hi Mod...

Thanks for helping...

Web C is shut tight...
IP that is not in the allow list is blocked in router level.

That is why i want to simulate the IP from one of the allow list server to access it.

Please let me know if this is possible or not.