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MS SQL connection failure log for TLS/encryption issues

pl flag
Jay

I have an application which has suddenly failed to login to a MS SQL database on the same LAN. On the client side logs I can see: [Microsoft][SQL Server Native Client 11.0]Encryption not supported on the client. # #

Now if i look at the MS SQL audit/login logs, there is no trace of this. Logs are enabled as per https://stackoverflow.com/questions/6769099/where-are-sql-server-connection-attempts-logged

Are there any other special/different log locations that catch connection errors at the security protocol and below?

Thanks!

rvsc48 avatar
gh flag
If the option in SSMS under the Instance properties>Security>FailedLogins is at least checked, it should be writing TLS connection errors to the Sql Server Error log to the Sql side. I know you said you are already seeing these in the client application logs. Are you seeing any in the Sql Server error log?
pl flag
Jay
Failed logins are already checked - no i do not see any indication of failed TLS connections in the SQL log.
rvsc48 avatar
gh flag
You could start a Profiler trace and watch it while the connection is attempting to be made. If you don't see anything in the Profiler results, then you can say the connection attempt is not even making it over to Sql Server.
Score:0
pl flag
Jay

@rvsc48 i think you're right it has not reached the server at all i now know that the client machine had their usable security protocols changed/enforced, so looks like the client's Windows OS has prevented the SQL client there from using TLS1.0. I'm not sure where I could see this on the client event logs, but it does explain why it doesn't show up on the SQL server side.

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