# vmnet_subnet_mask_key A string that represnts the IPv4 subnet mask to use on the interface. ``` let vmnet_subnet_mask_key: UnsafePointer ``` ## Discussion You must also specify `vmnet_start_address_key` and `vmnet_end_address_key` that you supply in the `interface_desc` and `interface_param` dictionaries. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)