How To Stop Failed Log On

[MpsLand]

hello all, how are you?

there are many failed log on in my windows server 2008 r2 event log. here is one example from my event viewer:
--start quote--
An account failed to log on.
Subject:
Security ID: NULL SID
Account Name: -
Account Domain: -
Logon ID: 0x0
Logon Type: 3
Account For Which Logon Failed:
Security ID: NULL SID
Account Name:
Account Domain: WORKGROUP
Failure Information:
Failure Reason: Unknown user name or bad password.
Status: 0xc000006d
Sub Status: 0xc0000064
Process Information:
Caller Process ID: 0x0
Caller Process Name: -
Network Information:
Workstation Name: --random name--
Source Network Address: --random ip --
Source Port: 13960
Detailed Authentication Information:
Logon Process: NtLmSsp
Authentication Package: NTLM
Transited Services: -
Package Name (NTLM only): -
Key Length: 0
--end quote--

these attempts are so many and periodically. sometimes they up to 30 attempts in only 1 minute, and it happens almost 24 hours nonstop

my question is: what is that and how to make it stop?

please kindly help me, thank you very much

regards,
sebastian

 

[ICTCity]

Also if you don't use / have IIS, check this KB:
http://support.microsoft.com/kb/896861/en-us

 

[MpsLand]

hi, thanks for your help. i have read the kb and it is because "loopback check security feature that is designed to help prevent reflection attacks on your computer", right?
so, it is not harmful and just leave it alone or should i follow the kb and "Specify host names for NTLM authentication" or "Disable the loopback check" in the registry?

again thank you very much for your kind help

 

[ICTCity]

Let's say that I don't have an answer. This is my though:

Don't disable the loopback check, actually it's not causing problem... right? What you could do is to specify NTLM host names, which is easy and safe.

I really don't know which is the best solution. I had just one time this problem and I resolved with NTLM host names but I didn't make any test to understand which scenario is better.

 

[MpsLand]

ok, thank you very much. i would now try to specify NTLM host names. and see the result. again, thank you