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WCF: Review System.Net and Network traces for Windows Authentication/Delegation based troubleshooting

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WCF: Review System.Net and Network traces for Windows Authentication/Delegation based troubleshooting

System.Net traces

<?xml version="1.0" encoding="utf-8" ?>

<configuration>

<system.diagnostics>

<trace autoflush="true" />

<sources>

<source name="System.Net">

<listeners>

<add name="System.Net"/>

</listeners>

</source>

<source name="System.Net.HttpListener">

<listeners>

<add name="System.Net"/>

</listeners>

</source>

<source name="System.Net.Sockets">

<listeners>

<add name="System.Net"/>

</listeners>

</source>

<source name="System.Net.Cache">

<listeners>

<add name="System.Net"/>

</listeners>

</source>

</sources>

<sharedListeners>

<add  name="System.Net"  type="System.Diagnostics.TextWriterTraceListener"

initializeData="c:\traces\System.Net.trace.log"   traceOutputOptions="DateTime"  />

</sharedListeners>

<switches>

<add name="System.Net" value="Verbose" />

<add name="System.Net.Sockets" value="Verbose" />

<add name="System.Net.Cache" value="Verbose" />

<add name="System.Net.HttpListener" value="Verbose" />

</switches>

</system.diagnostics>

</configuration>

 

Once the data is collected follow below steps to review:

  • Search for following key words “InitializeSecurityContext”
  • This will give you the socket number associated with the request:

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  • Follow the socket number upwards and you should see the web request associated with it.

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  • You might see multiple “InitializeSecurityContext” call, so make sure to search for one more key word “Received headers”

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  • This received header is very crucial as it contains the authentication scheme supported by server and the challenge for authentication.
  • Just after this, we should find the “InitializeSecurityContext” call with the service principle name listed.. used to get the Kerberos token from DC

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  • As we can see above, I am using the SPN listed via “targetName” value. Above screen shows that I am using a BAD SPN and eventually this will fail to get the Kerberos Token from DC
  • In just next frame, you can see client trying to use a NTLM toknen:

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Network traces review

  • Next we will see how we read this conversation over the Network, because Network traces will also reflect that we failed to get Kerberos token.
  • Once you have the data collected, please use following filter to review the logs “Kerberosv4 / Kerberosv5”'

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  • Now we should try to review the Response received from the DC, many a time you might find multiple responses received and it may be difficult to identify the one which we called.
  • So the trick is, with in the response… you will see the service principle name set/seen via System.Net traces

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  • As we can see this response is indeed coming for the request we initiated... and along with that we also Kerberos error code:

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  • Keep this kb handy to review the status codes:

https://technet.microsoft.com/en-us/library/cc738673%28v=ws.10%29.aspx

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  • Clearly error indicates that the service principle name is not registered.

Hope this helps in performing basic troubleshooting for windows authentication/delegation failure.

 

Thanks

Saurabh Somani