Sunday, February 28, 2010

Terminal Server Refuses New Connection.

Problem: Terminal Server Refuses New Connections

Error: Event Log Shows 'The terminal server received a large number of incomplete connections. The system may be under attack.'

Problem is caused by too many logon /logoff actions at the same time.

Obviously this could be caused by an attack but if you're like me, it was caused by too much activity at once.


In HKLM\System\CurrentControlSet\Control\TerminalServer , add the following DWORD value: MaxOutstandingConnect

You will need to add the value in hexadecimal format.

For Example:
50 is entered as 32 hex
75 is entered as 4b hex

Then reboot the server and your issue is resolved.

This has been tested and validated on the following OS's:

Windows Server 2008
Windows Server 2008 x64
Windows Server 2008 R2


MJ said...

Hi Jacob,

Thanks for providing the resolution, as you have mentioned that the resolution works on 2008 but does that apply to windows server 2003 R2 SP2 as well? As i am getting the same issue on the above mentioned operating system.

Looking forward to hear from you.

Jacob Ackerman said...

It should work on that OS as well, just backup your registry setting first - just in case.