[Semibug] backup files over serial console

Mark Moellering markmoellering at psyberation.com
Sun Mar 17 09:35:07 EDT 2019

Thanks Nick.

  I wasn't sure if the bsd.rd file would give me a shell prompt or not.
That's great!  I will let everyone know how well it turns out

On Sat, Mar 16, 2019 at 11:39 PM Nick Holland <nick at holland-consulting.net>

> On 3/16/19 9:50 PM, Mark Moellering wrote:
> > I am trying to put OpenBSD on an ubiquiti edgerouter - 4.  I was able
> > to install it on a EdgeRouter-Lite but that was easier, as I could open
> > the case and everything was installed on a USB stick.
> > the EdgeRouter-4 cannot be opened (or I haven't figure out how).  I am
> > pretty sure I can install OpenBSD but I would like to try and make a
> > backup of the software first.Â
> >
> > As near as I can tell, this needs to be done over the serial cable.  I
> > really can't figure out how to do this.  I read the cu man page and it
> > says:
> > Â Â Â Â
> >
> > Copy file from remote to local.  The *cu* utility prompts first for
> >            the name of the file to be sent, then for a command to be exe-
> >            cuted on the remote machine.
> >
> > I have no idea what this means... I am more of a programmer who uses
> > FreeBSD / openBSD
> > than a sysadmin, so I am pretty lost at this point. Can someone explain
> > what this means or how to
> > backup directories, etc over the console? Or is there another / better
> > way to do this?
> cu can be used to transfer text files -- capturing the output of 'cat' or
> sending text files as if you are typing rapidly.  Not so good for binary
> stuff.  You would have to add something like xmodem to actually move
> binary stuff over the serial port.
> You probably don't want to send gigabytes of data over a serial port
> anyway.  Serial ports are slow.
> I see there's a USB port on it.  Assuming that's supported by OpenBSD
> (hm. looks like it might be imperfect), I'd boot from the OpenBSD bsd.rd
> kernel (the install kernel) and dd the on-board storage to a file on the
> USB drive, or even image it directly to the USB drive.
> For example, assuming the on-board storage is sd0 and the USB drive is sd1:
>    # cd /dev
>    # sh MAKEDEV sd1    # because this isn't in RAMDISK kernels)
>    # dd if=/dev/rsd0c of=/dev/rsd1c bs=1m
> (wait)
> Note: this creates an IMAGE on sd1, you probably can't jam it in another
> machine and see files.  IF you "mount" the USB stick first, you could
> change the of to "of=/mnt/er4.img", however, if you use FAT, you might
> have issues with big files.  If you use FFS, you will probably find that
> FFS is not platform neutral; you can't be sure you can read the files on
> another machine other than another Octeon system.
> Looks like the OpenBSD support of the USB port might require a little
> pre-boot magic before working, so I'd recommend making two copies and
> comparing them elsewhere before overwriting what you want.
> Nick.
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