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How to enable passthrough for USB Network Adapters claimed by ESXi CDCE Driver?

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As part of vSphere 7.0, ESXi now ships with a USB CDCE (Communication Device Class Ethernet) driver which can benefit customers with SB network adapters that support the CDCE specification as shared in this blog post HERE. This can especially be useful for those running a VMware Homelab where the onboard network adapter may not be supported and using a CDCE USB network adapter would allow you to install ESXi.

When a CDCE-supported USB network adapter is connected to an ESXi host, it will automatically be claimed by the CDCE driver as shown in the screenshot below.


If you are planning to use the USB network adapter for VMkernel traffic, then there is no workflow change like any other physical network adapter. However, if you intend to passthrough the USB network adapter to a VM, then you may find that it is not working as expected.


The reason for this is that ESXi has already claimed the USB device, assuming you wish to use it for VMkernel traffic. To change the behavior for a particular CDCE-supported USB network adapter, we just need to apply a USB Quirk which tells ESXi to ignore this adapter.

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Quick Tip - Enabling ESXi Coredumps to be stored on USB

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I was recently working with Engineering to reproduce an issue which causes an ESXi PSOD (Purple Screen of Death) and I wanted the generated ESXi coredump to simply write to the USB device, which I could easily grab.

As of ESXi 7.x, I know we had removed a few of the old ESXi kernel boot options for allowing ESXi to store coredumps on a USB device and the using the ESXi kernel boot option allowCoreDumpOnUsb=TRUE should now be used, however I was struggling to get it to work.

Since I was using a debug version of ESXi, I needed to install ESXi from scratch and I thought I could simpply add the required kernel option, as shown in the screenshot below, and I had assumed it would automatically configure the ESXi coredump file to be stored on the VMFS-L volume residing on the USB device.


After a couple of attempts, I finally realized that this particular ESXi kernel boot option, is literally that, a boot option that is only applicable after the initial ESXi installation. 🤦 Unlike other ESXi kernel boot options which can be used during the initial installation which would apply certain configuration changes, this setting applies after ESXi has been installed. Once I appended the setting, the ESXi coredump file was created in the VMFS-L volume and I was then able to reproduce the issue and generate vm-support bundle that included the coredump!

Changing the default HTTP(s) Reverse Proxy Ports on ESXi 8.0

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The process of changing the default ports for the ESXi Reverse Proxy service has always been pretty straight forward, which I had also shared back in 2015 HERE. While most customers stick with the default configuration (80 for HTTP and 443 for HTTPS), we do have some customers that need to change these ports to meet certain organization security and/or compliance requirements.

Disclaimer: VMware does not officially support modifying the default HTTP/HTTPS ports on an ESXi host.

I recently came across a customer report where the previous method for changing the ESXi Reverse Proxy ports on an 8.0 host no longer worked and the only thing that was shared was that the user could no longer run ESXCLI directly within the ESXi Shell, which I thought was a strange observation.

I deployed the latest ESXi 8.0b as a Nested ESXi VM and I went through the instructions I had outlined in my blog post HERE and changed the HTTPS port from 443 to 4444, which was the setup the user was looking to do and I ran into the exact same issue. At first, I thought maybe we actually no longer support this capability and decided to quickly test by using the remote version of ESXCLI, which allows you to specify a port as part of the connection and it failed with the same error.

UPDATE (07/31/23) - For ESXi 8.0 Update 1 instructions, please refer to this blog post HERE.

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