I have an OpenBSD 5.5 system that I once had physical access to and I was able to plug in a monitor to upgrade from 5.0 to 5.5.

Now it is installed in a location away from my residence in a spot which prohibits me from being able to plug in a monitor.

I have no problems with the system as is, it works fine for my needs, so I can't really justify deinstalling it just to perform an upgrade.

Is it possible to perform an upgrade remotely through ssh? I understand this is not recommended, which makes it sound like it is possible. I know how set it up to boot from an install image on the hard drive, but I can't actually figure out how it could be done since I was fairly sure the install image wouldn't allow for automatic configuration of the network and ssh server.

  • It should be possible, however the risk to lose control of it if you miss some critical step is huge. If you do not feel comfortable doing it, I would leave it alone. Why not putting together a similar system in a VM, or even replicate it via network, boot it in a VM, and do all the testing and steps to upgrade it and document the steps all the way? – Rui F Ribeiro Dec 2 '15 at 7:07
  • You cannot plugin a monitor, that is fine. Would you be able to plug in it an rs232/IP adapter connected to the same switch? – Rui F Ribeiro Dec 2 '15 at 7:13
  • Yes, I have access to the ports and the switch, I basically just don't have the time to spend at that location for an upgrade, and I can't fit a monitor in that location. Is there need for bios configuration for a serial console? – John Euell Dec 2 '15 at 7:24
  • Probably. However you can configure the kernel for it, and afterwards the booting system, and it is fair game in case something goes wrong, including loss of network connectivity as long as the kernel boots. – Rui F Ribeiro Dec 2 '15 at 7:26
  • Only problem is that the system in question is the router for that network... – John Euell Dec 2 '15 at 7:27
  1. Read the Upgrading without install kernel section of the OpenBSD Upgrade Guide: 4.5 to 4.6.
  2. Take a backup of your existing operating system.
  3. (Optional) Perform a test in a Virtual Machine (shouldn't take too long).
  4. Proceed with the upgrade.

Note: Having access to a serial console and / or Lights Out Management would be handy in case something goes wrong.

Tip: You could, in theory, perform an 'alternate disk install', should you have another disk handy and the option to choose an OS at boot (via LOM for example).


You might want to check out http://www.openbsd.org/cgi-bin/man.cgi/OpenBSD-current/man8/autoinstall.8?query=autoinstall—it’ll do what you want. There are some other projects like https://github.com/jedisct1/yaifo that more specifically address your requirements, but YAIFO hasn’t been maintained in quite some time. Like others have mentioned though, I highly recommend piloting this in a non-production environment first.

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