---
title: vmnet_interface_id_key
framework: vmnet
role: symbol
role_heading: Global Variable
platforms: [Mac Catalyst 13.0+, macOS 10.10+]
path: vmnet/vmnet_interface_id_key
---

# vmnet_interface_id_key

## Declaration

```swift
let vmnet_interface_id_key: UnsafePointer<CChar>
```

## Discussion

Discussion Interface identifier of the previously created interface. If no interface identifier is passed to the vmnet function, a new MAC address is generated and a interface identifier is associated to it. This identifier is passed back to the client in the interface_param dictionary. To re-use a previously generated MAC address, the interface identifier associated with the MAC address needs to be passed to the vmnet function in the interface_desc parameter. The value specified for this key should be of type XPC_TYPE_UUID. important: Specifying a value for vmnet_interface_id_key does not guarantee the return of MAC address associated with the identifier. In cases where the MAC address associated with the id cannot be granted, an error is returned to the caller. note: This key may also be used in an XPC dictionary for a interface_param argument, for which it represents the identifier mapping to the MAC address returned in vmnet_mac_address_key. See interface_param XPC Dictionary Keys for more information.

## See Also

### Constants

- [vmnet_operation_mode_key](vmnet/vmnet_operation_mode_key.md)