OpenBSD pcn0 Driver Issue Resolved

 Published on 4 Nov 2005 ·  Filed in Tutorial ·  375 words (estimated 2 minutes to read)

Well, sort of resolved. I was never able to make the pcn driver (from OpenBSD 3.8) actually work under VMware, but I did find information on how to disable the pcn driver and revert to the older le driver.

This archived Neohapsis discussion, followed by a quick e-mail exchange with the author of the thread (who, thankfully, was very responsive and very helpful) led me to the solution. Some of it I had to improvise on the fly, but here’s the overall process:

1. Boot from the OpenBSD 3.8 boot CD image (I pointed the virtual CD-ROM drive in the VM directly to the corresponding ISO image).

2. At the OpenBSD boot> prompt, type “-c” (without quotes) and press Enter. This takes you into User Kernel Config, or UKC.

3. At the UKC prompt, type “disable pcn” to disable the pcn driver.

4. Type “quit” at the next UKC prompt to exit the kernel config and proceed with the boot process. If you watch the boot process, you will see OpenBSD load the le driver and identify the virtual NIC as le1.

That’s all well and good, but how do you make the changes stick between reboots? Here’s how.

1. Once you’ve gotten OpenBSD fully installed and are rebooting for the first time after installation, follow the steps above to use the le driver for the next reboot.

2. Use the “config -e -o nbsd bsd” command (see the relevant man page for details) to modify the kernel again, only this time saving the changes to the file named nbsd.

3. Upon the next reboot after using the config command to create a new kernel file, specify the name of that new kernel file (nbsd in our example here) at the OpenBSD boot> prompt.

4. Assuming that everything works OK (it did for me), rename the original kernel to “bsd.original” and rename your new kernel to just “bsd”. Then, upon the next reboot, the pcn driver should be disabled and everything should work just fine.

Using this process, I now have two OpenBSD 3.8 VMs running and haven’t experienced any issues. Now, on to installing ClamAV on OpenBSD….(more details soon)

UPDATE: The pcn0 network driver from OpenBSD 3.9 works perfectly under VMware (at least, on ESX Server). I have posted more information here.

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