How to Troubleshoot TCP Ports That Stay in the SYN_RECEIVED State for Long Periods of Time (296692)

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If you suspect that the behaviors that you are encountering are caused by network problems, type the following command at a command prompt to view connections that are in the SYN_RECEIVED state: Output that is similar to the following text appears after you run this command: If you run the netstat command one hour later, the TCP ports are still in the SYN_RECEIVED state, which can occur if the registry keys that control the functionality of the TCP/IP protocol are in a non-functioning state. To resolve this problem, set the following registry keys back to their default values: If you find the SynAttackProtect key, and your computer is not under a SYN attack, delete this key. For additional information about how to know whether your system is under a TCP SYN attack, click the article number below to view the article in the Microsoft Knowledge Base: In addition, verify that your network is operating properly without losing a large number of frames. To do this, create a network trace. An indication of packet loss is a high number of TCP retransmission frames. Many advanced network sniffer tools, such as Microsoft Network Monitor 2.0, are able to locate TCP retransmissions.