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Revision as of 07:18, 9 May 2013 by Stefw (talk | contribs) (Change testing of short offsets first)


Demonstrate that MIT Kerberos 1.11 no longer requires clients to synchronize their system clocks with that of the KDC.


  1. Perform prerequisite setup before you run these tests.
  2. You need a domain account, either a user or administrator.
  3. Get the client's current system time.
     $ date 
     Mon Mar 11 15:47:05 EDT 2013 
  4. Set the system time on the client to be between one and two hours ahead.
    sudo date -s "next hour"
    sudo date -s "next hour"
    Yeah, running it twice is a simple way to do that

How to test

  1. Use an Active Directory domain user account to authenticate to the Active Directory server using kinit
    $ kinit user@AD.EXAMPLE.COM
    Password for user@AD.EXAMPLE.COM
    • Make sure that you capitalize the domain name.
    • If the above fails with 'Preauthentication failed' then you probably typed the wrong password.
    • There should be no output from this command.

Expected Results

  1. Check that you have an appropriate entry in your credentials cache using the klist command.
    $ klist
    • You should see a line that has a service principal named "krbtgt/AD.EXAMPLE.COM@AD.EXAMPLE.COM"

More: Other time offsets

Try setting other time offsets to break kerberos clock syncing:

* More than a day backwards
* More than a day forwards
* Small amount of time backwards


If you want to file a bug related to this issue, run the command with the the KRB5_TRACE=/dev/stderr environment variable, like this:

$ KRB5_TRACE=/dev/stderr kinit user@AD.EXAMPLE.COM