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# VZFileHandleNetworkDeviceAttachment

A network device that transmits raw network packets and frames using a datagram socket.

```
class VZFileHandleNetworkDeviceAttachment
```

## Overview

A [`VZFileHandleNetworkDeviceAttachment`](/documentation/Virtualization/VZFileHandleNetworkDeviceAttachment) object maps a network interface to a connected datagram socket. This attachment transmits data at the data link layer. You configure and manage the socket in your app, and manage the corresponding data transfers.

To configure a network device with a socket-based file handle:

1. Create a socket with the `SOCK_DGRAM` type in your app.
2. Create a <doc://com.apple.documentation/documentation/Foundation/FileHandle> from the socket’s file descriptor.
3. Create the [`VZFileHandleNetworkDeviceAttachment`](/documentation/Virtualization/VZFileHandleNetworkDeviceAttachment) object using the file handle.
4. Assign the attachment object to the [`attachment`](/documentation/Virtualization/VZNetworkDeviceConfiguration/attachment) property of a [`VZVirtioNetworkDeviceConfiguration`](/documentation/Virtualization/VZVirtioNetworkDeviceConfiguration) object.
5. Add the [`VZVirtioNetworkDeviceConfiguration`](/documentation/Virtualization/VZVirtioNetworkDeviceConfiguration) object to the [`networkDevices`](/documentation/Virtualization/VZVirtualMachineConfiguration/networkDevices) property of your [`VZVirtualMachineConfiguration`](/documentation/Virtualization/VZVirtualMachineConfiguration).

This attachment doesn’t require your app to have the <doc://com.apple.documentation/documentation/BundleResources/Entitlements/com.apple.vm.networking> entitlement.

## Topics

### Creating the attachment point

[`init(fileHandle:)`](/documentation/Virtualization/VZFileHandleNetworkDeviceAttachment/init(fileHandle:))

Creates the attachment from a file handle that contains a connected datagram socket.

### Getting the file handle

[`fileHandle`](/documentation/Virtualization/VZFileHandleNetworkDeviceAttachment/fileHandle)

The file handle assigned to this attachment.

### Specifying the network packet size

[`maximumTransmissionUnit`](/documentation/Virtualization/VZFileHandleNetworkDeviceAttachment/maximumTransmissionUnit)

An integer value that indicates the maximum transmission unit (MTU) associated with this attachment.


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