Use mobile phone tethered wired connection as network interface to USB A port on install target laptop. How to select USB A port on laptop as Network Interface?

[spazmodic]

Hi All.
When using netbootXYZ:

• Instead of using the default Ethernet port as the network interface on a laptop which is the target device for an install with netbootXYZ,
• I would like to select a USB 3.0 A port as the network interface for the target device.

Is this possible?
I can see in netbootXYZ that when it does NOT detect ethernet, it DOES allow you to select other interfaces using a numbering system. I think ethernet as the default is number 0 or 1.
Not sure if this is or might be a possible way to select a USB A port as a network interface for the target device.

In this case:

• I am installing to a crappy laptop which has a broken ethernet port.
• But this would also be VERY useful for using netbootXYZ "on the run" generally, as I have an abundance of USB C to USB A cables, and these are easy to find.
• However: a USB C to Ethernet cables are MUCH more difficult to find and come across, at least in my experience. I don't think I have a single one of these!

The setup and logic for my current target device (crappy laptop with broken ethernet jack) is:
I have my mobile phone with a USB C connection that can deliver a wired network connection when operating in "Tethered" mode.

I want to use this tethered network connection to use netbootXYZ to do installs on a crappy laptop that has a broken ethernet jack (or any other laptop) through the laptop's USB A port.

If this is possible:
I need to know how to select the USB A Port as the network interface.

I have tested this elsewhere and know the tethered wired network connection from the phone's data works for USB-C-to-USB-C interfaces, ie from phone to a laptop.
That is:
I have another laptop with a USB C Connection which can't get wifi on that OS.
I use my phone's tethered connection as the network access on that laptop (USB C port to USB C port) when I am away from home, and that works fine.

However, I realize this is a somewhat different case for a few reasons.

USB 3.0 certainly appears to have enough pins for this to be possible (8 and GND), Tx +/- and Rx +/-, so it seems like this might be possible.

Not sure if some kind of adapter other than a simple USB C to USB A cable is required.

Anyway, thoughts from somebody who knows way more stuff than me, and who might have an answer to this either way would be much appreciated.

Thanks!

[no-usernames-left]

USB 3.0 certainly appears to have enough pins for this to be possible (8 and GND), Tx +/- and Rx +/-, so it seems like this might be possible.

Unfortunately, this is not how it works. When you enable the wired hotspot mode, the phone presents another USB device which is selectable by the machine's OS, which is achieved using USB mode switching. The restricted environment in which netboot is running likely doesn't/won't have support for this.

[spazmodic]

Wow! That was a quick response. Thanks! And bugger. Thanks for the archwiki link. It's a good one. Well, fingers crossed there is some other/related/substitute method. Maybe not.

Do you perhaps have other articles or info on this topic of usb mode switching?

I would have thought something like "USB mode switching" sounds low level-enough that it might be able to be implemented in a small space and within a "restricted environment". Obviously as you/we mention, it can be used as a network interface that provides a network data-stream in the "less-restricted" setting of a full-blown OS, so I'm hoping it is not a far stretch to implement (if it is not already), but then again I've already shown what I know about this topic, which is practically nothing.

[NiKiZe]

Unless manufacturers have changed the protocol, iPXE itself does have support for the major implementations of tethering, however it has not been enabled by default in previous iPXE builds. So you need a build of iPXE with USB NIC support enabled. I think the latest builds on boot.ipxe.org does have it, but I have not verified.

To test create a USB with ipxe.efi and get that booting, Sounds like you have the basics for this already?
Run ifstat and see which nics you get, you should also be able to run dhcp to get an IP. - Remember tho, that your mobile will act as a router, so you will get the settings that your phone provides, and not the settings of the network it is connected to, so don't get confused by IP etc not matching your local network.

[spazmodic]

Thank you for this! Drowning in study at the moment, but I will come back and research and hopefully test this later.