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Weird problem installing SEB 1.9.1

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Tim Hunt
2013-06-21
2013-07-01
  • Tim Hunt
    Tim Hunt
    2013-06-21

    We have a weird situation where SEB works with one of our test servers, but not with another. Our two test servers are https://icmatest.vledev2.open.ac.uk/exams and https://learn6acct.open.ac.uk/. (You won't be able to access either of those, they are behind the OU firewall.) I will refer to these as icmatest and learn6.

    When we build an installer for SEB pointing at icmatest, everything works.

    When we build an installer for SEB pointing at learn6, then when you install it on a new computer and try to run it, you see this:

    1. The screen goes blank with a blue background (as normal)
    2. The swirly progress indicator appears in the middle of the screen and turns round for perhaps a minute.
    3. The swirly progress indicator goes away, and but the web page does not appear, so you are left staring at a blank blue screen.

    There is no real difference between the way the two servers are set up. The differences are:

    • icmatest is a single box.
    • learn6 is a pair of servers behind a load-balancer (netscaler), and is using the OU's single-sign-on system (which basically just means that you get redirected to another server to log in, then get redirected abck.)

    What is more weird is that, after it has failed, you can make it work as follows:

    • Install the version of SEB pointing at icmatest and run it.
    • Install the version of SEB pointing at learn6 again and run it. Now it works.

    Also, if you ahve previously installed SEB on a particular computer, installing the learn6 version just works.

    So, my questions are:

    A. Has anyone else seen a problem like this?
    B. When you do get a problem like this, are there any techniques to debug the problem? It is quite hard to debug a secure application ;-)

     
    • Dirk Bauer
      Dirk Bauer
      2013-06-25

      Hi Tim,

      I'm out of country this week and have very limited net access,
      so it is indeed difficult to debug. Cannot remember having heard of this
      particular problem but seems to that SEB (xulrunner) got confused
      by this special switching/redirection when trying to connect to the
      second server (exam URL). Maybe it worked later cos xulrunner
      browser component stored access data in LocalAppData of current user.
      Just my first assumption.

      Regards, Dirk


      Von: Tim Hunt [tjhunt@users.sf.net]
      Gesendet: Freitag, 21. Juni 2013 11:43
      An: [seb:discussion]
      Betreff: [seb:discussion] Weird problem installing SEB 1.9.1

      We have a weird situation where SEB works with one of our test servers, but not with another. Our two test servers are https://icmatest.vledev2.open.ac.uk/exams and https://learn6acct.open.ac.uk/. (You won't be able to access either of those, they are behind the OU firewall.) I will refer to these as icmatest and learn6.

      When we build an installer for SEB pointing at icmatest, everything works.

      When we build an installer for SEB pointing at learn6, then when you install it on a new computer and try to run it, you see this:

      1. The screen goes blank with a blue background (as normal)
      2. The swirly progress indicator appears in the middle of the screen and turns round for perhaps a minute.
      3. The swirly progress indicator goes away, and but the web page does not appear, so you are left staring at a blank blue screen.

      There is no real difference between the way the two servers are set up. The differences are:

      • icmatest is a single box.
      • learn6 is a pair of servers behind a load-balancer (netscaler), and is using the OU's single-sign-on system (which basically just means that you get redirected to another server to log in, then get redirected abck.)

      What is more weird is that, after it has failed, you can make it work as follows:

      • Install the version of SEB pointing at icmatest and run it.
      • Install the version of SEB pointing at learn6 again and run it. Now it works.

      Also, if you ahve previously installed SEB on a particular computer, installing the learn6 version just works.

      So, my questions are:

      A. Has anyone else seen a problem like this?
      B. When you do get a problem like this, are there any techniques to debug the problem? It is quite hard to debug a secure application ;-)


      Weird problem installing SEB 1.9.1https://sourceforge.net/p/seb/discussion/844844/thread/16c9eec9/?limit=50#e6d3


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  • Tim Hunt
    Tim Hunt
    2013-06-21

    My colleage Phil Butcher worked this out.

    We made a start page that was just a plain HTML page with a link to the learn6 URL, and made a version of SEB that started there. When you clicked on that link in SEB installed onto a clean machine, we got the error

    "Learn6acct uses an invalid security certificate. The certificate is not trusted because no issuer chain was provided. Error code:sec_error_unknown_issuer."

    Mozilla have a nice page explaining this: https://wiki.mozilla.org/Incomplete_Certificate_Chain. The section "But Sometimes It Works" explains why the problem eventually goes away.

    So, we need to fix our sever config. Would be nice if, when this problem occurs, the failure could be made less mysterious to SEB users.

     
  • Damn, we also had this problem once! I think there should be a discussion regarding this in the forum. Wait, we even have this mentioned in our documentation: http://www.safeexambrowser.org/windows/win_usermanual_en.html#Certificates

    The question regarding debugging is mentioned in the documentation of the (yet unofficial or not linked from safeexambrowser.org) SEB XULRunner browser component at:

    https://github.com/eqsoft/seb/blob/master/doc.md

    (we should somehow incorporate this documentation into safeexambrowser.org, latest when it gets more final regarding SEB 2.0, some functions still have to be implemented in the SEB XULRunner browser component)

    If something which has to do with the web browser of SEB Windows isn't clear enough, then searching mozilla.org or https://developer.mozilla.org is always a good idea (even though it might still not be easy to figure out).

     
    Last edit: Daniel Schneider 2013-07-01