I have an ASP.NET form (a login page), when I POST the values to the server (windows, IIS 6), the request passes through a proxy and the POST pareameters end up getting lost and ultimately the page just refreshes as there are no POST parameters.
The thing is that this is not a constant issue as sometimes you can log in fine and generally if you clear your browser temp files it then works ok.
I ran Fiddler to check what's going on and basically I'm getting:
A regular POST request containing session id, POST data etc. The response (HTTP 407) contains a Proxy-Authenticate: Negotiate and Proxy-Support: Session-Based-Authentication header.
The next request to the server contains a Proxy-Authorization: Negotiate header containing a long string (base64 i think). This request does NOT contain the POST values. The response is another 407 and actually now that i look at it Fiddler displays 'HTTP/1.1 407 Proxy Authentication Required ( Access is denied. )' as the header.
Then there's a third request that contains the Proxy-Authorization header and returns 200 OK, but of course the POST values weren't sent Subsequent requests result in a HTTP/1.1 407 Proxy Authentication Required ( The ISA Server requires authorization to fulfill the request. Access to the Web Proxy filter is denied. ) response followed by a second successful but empty request.
The client won't let me bypass the proxy as it's intermittent and all other pages in the application (that include plenty of web forms) work fine.
Any ideas on what I can try?