14 March 2014

What are "Schannel" errors and how to stop logging them

With certain Microsoft products, such as Exchange and Lync you see your evelogs filling up with "Schannel" errors; event id: 36888 The following fatal alert was generated: 51. The internal error state is 1306.

The event it self doesnt give out a lwhole lot of information but here is an explanation for it from technet:

When you enable Schannel event logging on a computer that is running Microsoft Windows NT Server 4.0, Microsoft Windows 2000 Server, Microsoft Windows XP Professional, Microsoft Windows Server 2003, Microsoft Windows Server 2008, or Microsoft Windows Server 2008 R2, detailed information from Schannel events can be written to the Event Viewer logs, in particular the System event log. This article describes how to enable and configure Schannel event logging. 

The internal error state is 1203 - From a support forum: "This event is seen on windows 2008 R2 running IIS. If a user tries to access a web site using HTTP but specifies an SSL port in the URL then this event is logged. This event is expected as the client is trying to use the wrong port or the wrong protocol to access the site
The error 1203 indicates invalid ClientHello from the client. This is by design and you can ignore this warning."

If your System eventlog is filling up with "Schannel" errors, and you want to stop this behavior, you can do the following.

Enable /disable logging

Warning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall your operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.

Note This registry key is present already in Windows 2000 and XP Professional.
  1. Start Registry Editor. To do this, click Start, click Run, type regedt32, and then click OK.
  2. Locate the following key in the registry:
  3. On the Edit menu, click Add Value, and then add the following registry value:
    Value Name: EventLogging
    Data Type: REG_DWORD
    Note After you add this property, you must give it a value. See the table in the "Logging options" section to obtain the appropriate value for the kind of events that you want to log.
  4. Exit Registry Editor.
  5. Click Start, click Shut Down, click to select Restart, and then click OK to restart the computer. (Logging does not take effect until after you restart the computer).

Logging options

The default value for Schannel event logging is 0x0000 in Windows NT Server 4.0, which means that no Schannel events are logged. In Windows 2000 Server and Windows XP Professional, this value is set to 0x0001, which means that error messages are logged. Additionally, you can log multiple events by specifying the hexadecimal value that equates to the logging options that you want. For example, to log error messages (0x0001) and warnings (0x0002), set the value to 0x0003.
Collapse this tableExpand this table:

0x0000                  Do not log
0x0001                  Log error messages
0x0002                  Log warnings
0x0004                  Log informational and success events


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