at home server without screen blocked by bad ipfw conf -- live boot usb with sshd

[Fabian Keil]

Orka Edison <orka.edison at ovh.fr> wrote:

> i brink my at home by a bad ipfw.rules...
> 
> how can i créate an usb boot key with sshd for access to my server ?
> with an fixed IP and tools-box for repair my machine.

I use a script to adjust the UFS partition on an image
created by the "memstick" target after it has been copied
to the USB stick.

The relevant script content:

    set -e -x
    mount "${device}" /mnt/
    [...]
    mkdir -p /mnt/root/.ssh
    echo 'ssh-ed25519 [...]' > /mnt/root/.ssh/authorized_keys
    chmod -R go-rwx /mnt/root/.ssh
    echo 'PermitRootLogin yes' >> /mnt/etc/ssh/sshd_config
    echo 'ifconfig_re0=192.168.5.48' >> /mnt/etc/rc.conf
    echo 'sshd_enable="YES"' >> /mnt/etc/rc.conf
    sed -e 's at ro, at rw,@' -i.bak /mnt/etc/fstab
    cat /mnt/etc/fstab
    umount /mnt

You'll have to add your own public ssh key, adjust the rc.conf
modification and maybe add a default router if needed.

If you simply messed up the ipfw rules the memstick image
should contain everything you need to fix it.

If you are in a hurry and don't mind using unreproducible binaries
built by third parties you could download a memstick image from
freebsd.org instead of building it yourself.

Fabian
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