I found a workaround, in ipcop: leave "enabled on green" proxy checked, but uncheck "transparent on green" proxy.
Then setup web browser to use proxy in manual configuration to use ipcop ip address and use port 800 for all entries (tested in firefox).
Then put in address to force authentication in No Proxy for at the bottom.
This forced authentication for the website I wanted and antivirus is still working in copfilter - eicar test.
Firefox -> tools -> options-> advanced -> network -> settings ->
my ipcop ip is 192.168.1.252
web address that needs authentication admin.spatechadmin.com
*** need to clear cache in ipcop and firefox to test after you make changes.
Firefox setting looked like this:
Attachment:
setting.jpg [ 142.97 KiB | Viewed 3133 times ]