Host-Only Networking and Port Forwarding Support in macOS Virtualization Framework

For both host-only and port forwarding, teams typically implement the networking themselves using the VZFileHandleNetworkDeviceAttachment.

This requires a user-space network stack. There are a few open source projects that can be used there.

Given that the whole stack becomes under the control of the app, the exact policy for how VMs are connected and ports handled is fully customizable through the implementation.

For best performance, it's recommended to use the VZFileHandleNetworkDeviceAttachment.maximumTransmissionUnit to set a large MTU for such mode. That reduces the emulation overhead for each packet. Another valuable parameter is the buffer size of the sockets passed through the NSFileHandle.

Thank you for the reply. it seems to be that this is a bit complex task for a novice. can you please guid me on where to look for some samples on how to achive this using VZFileHandleNetworkDeviceAttachment

Hmm, yes, if you aren't already familiar with userspace networking, this is definitely a large task to start.

You may want to create feature requests for each one of the features you mentioned while explaining what you are trying to achieve. This will help the teams track demand for such features.

If you are just trying to get a channel between host and guest, would VZVirtioSocketDevice be a solution? It is efficient and private for each VM.

Thanks for the heads up. i will create a feature request. This is not just to get a channel between host and guest. This is for creating isolated host only network with guest and also a port forward from host to guest. i am trying to add these features to my virtual machine manager application. I dont have expertise in creating user space networking.

Just to answer my own question now it is possible to do this with macOS 26 with custom vmnet network.

Indeed. Thanks for closing the loop here.

And just for the sake of those following along at home, I wanted to post a couple of links to rbmanian75’s other threads, where we’ve been discussing the mechanics, and the limitations, of this technique:

• Port forwarding with VZVmnetNetworkDeviceAttachment
• Programmatic IP Discovery for VZVirtualMachine in an App Store Sandbox

Actually, come to think of it, rbmanian75’s All Posts page currently reads like a Virtualization FAQ (-:

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Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

Actually, come to think of it, rbmanian75’s All Posts page currently reads like a Virtualization FAQ (-:

The reason for it is obvious to bring this app to https://apps.apple.com/us/app/virtualprog-virtual-machine/id6744131218?mt=12 to mac app store. sorry for shameless self promo.