Windows identity getting confused between users

Discussion in 'ASP .Net' started by Scottrm, Jun 30, 2010.

  1. Scottrm

    Scottrm Guest

    We are observing some strange behaviour in our web server logs where where
    the Identity of the currently logged in user seems to be getting swapped with
    another user. I will describe our set up before explaining further.

    We are running an web site (v3.5 of the framework) on 2 Windows 2008
    web servers and use forms authentication.They are load balanced using a
    separate server running Apache 2.2 on Linux (Cent OS 5). The load balancing
    simply attaches a cookie to a user and directs them to a particular server
    for each subsequent request.

    We notice on occasion patterns in the log like this (details obfuscated)

    First Log Entry

    UserName -

    UserId - 1111

    WebPage - page1

    IP - ip1

    Time - 2010-06-29 12:56:20.750

    SessionId - h3uyz2fsdfegugjy452sdz0far

    Second Log Entry

    UserName -

    UserId - 2222

    WebPage - page2

    IP - ip2

    Time - 2010-06-29 12:57:16.133

    SessionId - 21ipjsdfsdfieqqwyfdokgqsb55

    We are using forms authentication using the standard forms
    authentication framework (the standard login control and we implemented a
    custom membership provider).

    The UserName is the Windows identity retrieved using
    "HttpContext.Current.User.Identity.Name" The UserId is the database Id set in
    the session. The sessionId is retrieved using

    As you can see the same Windows identity is the same for 2 different users,
    under different IP addresses and with different session id's, hitting the
    site about the same time. We checked and the IP's were from totally different
    locations. The wrong windows identity seems to be getting recorded. UserId
    2222 should have a different username recorded.

    Since it happens very occasionally, the code is standard and has not changed
    substantially for some time we don't "think" it is a coding error. We presume
    either a problem with the load balancer or some problem in the web server. I
    have never heard of such problems in before.

    Recently we did change our set up from IIS6 on Windows 2003 and a Cisco
    hardware load balancer to the current setup of IIS7 on Windows 2008 and the
    Apache load balancing. Any ideas appreciated.

    The forms authentication entry in the web.config is

    authentication mode="Forms"

    forms loginUrl="LoginPage.aspx" name=".ASPXFORMSAUTH"
    Scottrm, Jun 30, 2010
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