ensuring referrer address

[Sharon]

Hi all,
I need to ensure that a client using a popup service on my site,
was referred by an authorized host.
The referrer server variable is sent by the client,
and therefor is not reliable.
Do you know of other ways to do this?
Thanks,
Sharon.

 

[Peter Rilling]

Do you control the authorized hosts?

If you do not control the hosts, then I would say it is not possible.
Otherwise you could use something like cookies. But even cookies can be
spoofed.