November 13, 2020 at 9:38 pm
Hello,
I am trying to find the cause for an error that is creating a lot of noise in our audit logs. I am able to reproduce this error whenever I telnet to our server (on the sql server port) and the connection is closed or times out. This error also shows up when a few of our application servers close their connection from the sql server as well.
Error when telnet connection is manually closed:
Network error code 0x2746 occurred while establishing a connection; the connection has been closed. This may have been caused by client or server login timeout expiration. Time spent during login: total 9671 ms, enqueued 0 ms, network writes 0 ms, network reads 9670 ms, establishing SSL 0 ms, network reads during SSL 0 ms, network writes during SSL 0 ms, secure calls during SSL 0 ms, enqueued during SSL 0 ms, negotiating SSPI 0 ms, network reads during SSPI 0 ms, network writes during SSPI 0 ms, secure calls during SSPI 0 ms, enqueued during SSPI 0 ms, validating login 0 ms, including user-defined login processing 0 ms. [CLIENT: 137.190.###.###]
Error when telnet times out:
StatementNetwork error code 0x102 occurred while establishing a connection; the connection has been closed. This may have been caused by client or server login timeout expiration. Time spent during login: total 110051 ms, enqueued 0 ms, network writes 0 ms, network reads 110050 ms, establishing SSL 0 ms, network reads during SSL 0 ms, network writes during SSL 0 ms, secure calls during SSL 0 ms, enqueued during SSL 0 ms, negotiating SSPI 0 ms, network reads during SSPI 0 ms, network writes during SSPI 0 ms, secure calls during SSPI 0 ms, enqueued during SSPI 0 ms, validating login 0 ms, including user-defined login processing 0 ms. [CLIENT: 137.190.###.###]
I am at a loss. Please let me know if you have any ideas on why this error might be popping up.
November 14, 2020 at 10:10 pm
Thanks for posting your issue and hopefully someone will answer soon.
This is an automated bump to increase visibility of your question.
November 15, 2020 at 7:13 am
Would say you have a network issue somewhere. Have you spoke to the networking admins and asked them to trace route and packet capture so you can see whats going on network side when these things happen?
What other errors are in the eventlog/errorlog at the same time, any 18456 errors at all?
Do you have any custom login triggers enabled which may cause this?
What is the server activity when trying to connect, CPU maxed out, RAM maxed out, number of concurrent sessions, worker threads in use etc? What monitoring of SQL is in place?
Whats the configuration? MultiSubnet AOAG with all IP's registered? Failed connections are coming from the other subnet where SQL is not running from?
The list is endless so needs some proper monitoring of all the kinks in the chain to see where the problem is stemming from
November 17, 2020 at 4:54 pm
Thanks Anthony,
I am working with my network admins now to see if we can see anything on their end.
No other errors show up when this error is logged.
No custom login triggers in place. We use mixed mode.
The server resources don't spike when this error is logged, we have max concurrent sessions set to Zero. We are using SQL Sentry to monitor the databases, and Icinga to monitor server resources.
We have some servers using multiple subnet AOAG and some not. The failed connection logs come in regardless of AOAG.
The only thing I can think, is that if a connection (like telnet) is testing the connection over the sql server port without sending SQL credentials for the database instance, it is failing to authenticate because it isn't sending credentials.
As far as I can tell, I am able to connect to the sql server though the sql server port, but if I don't send credentials, it closes the connection and creates this error.
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