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Update troubleshoot-tcpip-port-exhaust.md

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Denise Vangel-MSFT 2022-02-07 16:20:04 -08:00 committed by GitHub
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windows/client-management/troubleshoot-tcpip-port-exhaust.md
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@ -22,7 +22,7 @@ There are two types of ports:
- *Ephemeral ports*, which are usually dynamic ports, are the set of ports that every machine by default will have them to make an outbound connection. - *Ephemeral ports*, which are usually dynamic ports, are the set of ports that every machine by default will have them to make an outbound connection.
- *Well-known ports* are the defined port for a particular application or service. For example, file server service is on port 445, HTTPS is 443, HTTP is 80, and RPC is 135. Custom application will also have their defined port numbers. - *Well-known ports* are the defined port for a particular application or service. For example, file server service is on port 445, HTTPS is 443, HTTP is 80, and RPC is 135. Custom application will also have their defined port numbers.
Clients when connecting to an application or service will make use of an ephemeral port from its machine to connect to a well-known port defined for that application or service. A browser on a client machine will use an ephemeral port to connect to https://www.microsoft.com on port 443. When connecting to an application or service, client devices use an ephemeral port from the device to connect to a well-known port defined for that application or service. A browser on a client machine will use an ephemeral port to connect to `https://www.microsoft.com` on port 443.
In a scenario where the same browser is creating a lot of connections to multiple websites, for any new connection that the browser is attempting, an ephemeral port is used. After some time, you will notice that the connections will start to fail and one high possibility for this would be because the browser has used all the available ports to make connections outside and any new attempt to establish a connection will fail as there are no more ports available. When all the ports on a machine are used, we term it as *port exhaustion*. In a scenario where the same browser is creating a lot of connections to multiple websites, for any new connection that the browser is attempting, an ephemeral port is used. After some time, you will notice that the connections will start to fail and one high possibility for this would be because the browser has used all the available ports to make connections outside and any new attempt to establish a connection will fail as there are no more ports available. When all the ports on a machine are used, we term it as *port exhaustion*.
@ -97,14 +97,14 @@ If you suspect that the machine is in a state of port exhaustion:
After a graceful closure or an abrupt closure of a session, after a period of 4 minutes (default), the port used by the process or application would be released back to the available pool. During this 4 minutes, the TCP connection state will be TIME_WAIT state. In a situation where you suspect port exhaustion, an application or process will not be able to release all the ports that it has consumed and will remain in the TIME_WAIT state. After a graceful closure or an abrupt closure of a session, after a period of 4 minutes (default), the port used by the process or application would be released back to the available pool. During this 4 minutes, the TCP connection state will be TIME_WAIT state. In a situation where you suspect port exhaustion, an application or process will not be able to release all the ports that it has consumed and will remain in the TIME_WAIT state.
You may also see CLOSE_WAIT state connections in the same output, however CLOSE_WAIT state is a state when one side of the TCP peer has no more data to send (FIN sent) but is able to receive data from the other end. This state does not necessarily indicate port exhaustion. You might also see CLOSE_WAIT state connections in the same output; however, CLOSE_WAIT state is a state when one side of the TCP peer has no more data to send (FIN sent) but is able to receive data from the other end. This state does not necessarily indicate port exhaustion.
>[!Note] > [!Note]
>Having huge connections in TIME_WAIT state does not always indicate that the server is currently out of ports unless the first two points are verified. Having lot of TIME_WAIT connections does indicate that the process is creating lot of TCP connections and may eventually lead to port exhaustion. > Having huge connections in TIME_WAIT state does not always indicate that the server is currently out of ports unless the first two points are verified. Having lot of TIME_WAIT connections does indicate that the process is creating lot of TCP connections and may eventually lead to port exhaustion.
> >
>Netstat has been updated in Windows 10 with the addition of the **-Q** switch to show ports that have transitioned out of time wait as in the BOUND state. An update for Windows 8.1 and Windows Server 2012 R2 has been released that contains this functionality. The PowerShell cmdlet `Get-NetTCPConnection` in Windows 10 also shows these BOUND ports. > Netstat has been updated in Windows 10 with the addition of the **-Q** switch to show ports that have transitioned out of time wait as in the BOUND state. An update for Windows 8.1 and Windows Server 2012 R2 has been released that contains this functionality. The PowerShell cmdlet `Get-NetTCPConnection` in Windows 10 also shows these BOUND ports.
> >
>Until 10/2016, netstat was inaccurate. Fixes for netstat, back-ported to 2012 R2, allowed Netstat.exe and Get-NetTcpConnection to correctly report TCP or UDP port usage in Windows Server 2012 R2. See [Windows Server 2012 R2: Ephemeral ports hotfixes](https://support.microsoft.com/help/3123245/update-improves-port-exhaustion-identification-in-windows-server-2012) to learn more. > Until 10/2016, netstat was inaccurate. Fixes for netstat, back-ported to 2012 R2, allowed Netstat.exe and Get-NetTcpConnection to correctly report TCP or UDP port usage in Windows Server 2012 R2. See [Windows Server 2012 R2: Ephemeral ports hotfixes](https://support.microsoft.com/help/3123245/update-improves-port-exhaustion-identification-in-windows-server-2012) to learn more.
4. Open a command prompt in admin mode and run the below command 4. Open a command prompt in admin mode and run the below command