An attack on port 1720 may cause NetMeeting to refuse incoming connections after more than approximately 200 Transmission Control Protocol (TCP) connections are opened. If you apply the fix that is mentioned in the following Microsoft Knowledge Base article, this problem is not resolved:
MS00-077: Denial of Service Can Occur with Microsoft NetMeeting
This problem occurs because of the way that NetMeeting handles TCP connections in the Callcont.dll dynamic link library.
To resolve this problem, obtain the latest service pack for Microsoft Windows 2000. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:
How to Obtain the Latest Windows 2000 Service Pack
Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article. This problem was first corrected in Microsoft Windows 2000 Service Pack 4.