Will failed login attempts cause SQL Server performance issues?

  • I'll be honest I really know jack about the inner workings of SQL, so any help would be appreciated. Trying to help my boss figure out why we have been having Server Too Busy errors with our website all day. The tech support at our hosting company seem to think it is an issue with too many concurrent connections to the database. I was looking in the log, and saw some thousands and thousands of failed attempts by some IP in Mubai to login using our sa account. Could that be causing us any issues?

  • How many times a second are the errors?

    High number of login attempts can chew up CPU, but it would have to be very frequent.

    Generally, any SQL server instance running on port 1433 and whose IP is not blocked by a firewall,

    will see sa login attempts, primarily coming from IPs in China.

  • 5 to 8 times a second for about 6 hours from the same IP.

  • And is CPU high on the SQL server box?

    Is there a particular reason your SQL server is not behind a firewall?

  • As a related question, if the port is set to 1433, should it be changed to prevent this? Is this typical hacker type of issues?

    [font="Arial"]“Any fool can know. The point is to understand.”
    - Albert Einstein

    "DOH!"
    - Homer Simpson[/font]

  • As a rule I don't like to run on 1433.

    Yes, any scanning tool out there will try to attack 1433 first.

    They will try to log in as sa and sometimes other logins such as dbadmin or some such thing.

    Also they will throw a malformed packet at the port to see if they get something useful back.

  • arnipetursson (12/18/2012)


    And is CPU high on the SQL server box?

    Is there a particular reason your SQL server is not behind a firewall?

    I'll be honest, I am neither a DBA or a Network guy, and I've only been here a week. So my knowledge on why and how the database and web servers are setup is very limited.

  • Its may be a performance related issue ...

    check you CPU usage and memory usage for the sql server

    If its taking much percentage as expected ..you should reorganize the indexes and

    defragment your SQL database

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