# vmnet_enable_virtio_header_key Enable virtio headers in all packets. ``` let vmnet_enable_virtio_header_key: UnsafePointer ``` ## Discussion For more information, see [5.1.6 Device Operation](https://docs.oasis-open.org/virtio/virtio/v1.1/virtio-v1.1.html) in the Virtio specification You must not specify this property if [`vmnet_enable_checksum_offload_key`](/documentation/vmnet/vmnet_enable_checksum_offload_key) is specified. --- 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)