Authentication behind F5 LineRate issue.

A good next step would be to take a packet capture on the client side and see 1) what types of headers are coming back (particularly WWW-Authenticate) from the server and 2) how far into the negotiation process you get (ie. what are the packets you get in your conversation) to determine where things are failing. It may be worthwhile, too, to compare the conversation with LineRate in the middle to the one directly taking to the server successfully. This research should help you figure out what needs to be tweaked to get everything to work. Here's a good MSDN article on what you might want to look for when Negotiate is the primary means of auth: http://blogs.msdn.com/b/benjaminperkins/archive/2011/09/14/iis-integrated-windows-authentication-with-negotiate.aspx