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Configure alternative SMB ports (preview)

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Important

Windows Server Insider builds are in PREVIEW. This information relates to a prerelease product that may be substantially modified before it's released. Microsoft makes no warranties, expressed or implied, with respect to the information provided here.

You can use the SMB client to connect to alternative TCP, QUIC, and RDMA ports. However, you can only connect to alternative ports if the SMB server is configured to support listening on that port.

You can also configure your deployment to block configuring alternative ports or specify that ports can only connect to certain servers.

Prerequisites

In order to configure alternative ports, you need the following:

Map an alternative port

To map an alternative port to your SMB client:

  1. Open an elevated PowerShell window as an administrator.

  2. Run one of the following commands to map a port:

    • Run this command to map a TCP port:

      New-SmbMapping -LocalPath <drive letter>: -RemotePath \\server\share -TcpPort <port number between 0 and 65536>

    • Run this command to map a QUIC port:

      New-SmbMapping -LocalPath <drive letter>: -RemotePath \\server\share -QuicPort <port number between 0 and 65536>

    • Run this command to map an RDMA port:

      New-SmbMapping -LocalPath <drive letter>: -RemotePath \\server\share -RdmaPort <port number between 0 and 65536>

Control or block alternative port usage

The SMB server in Windows and Windows Server only supports changing the SMB over QUIC listening port. You can't configure TCP or RDMA listening ports.

The only method currently available to configure alternative ports is through PowerShell. You can configure the SMB over the QUIC server to use an alternative port by running the following commands:

#Lists all available alternative ports
Get-SmbServerAlternativePort 

#Creates a new alternative port
New-SmbServerAlternativePort -TransportType QUIC -Port <port number> -EnableInstances Default

#Deletes an alternative port
Remove-SmbServerAlternativePort

#Configures SMB to use a specific port
Set-SmbServerAlternativePort

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