mount_vnd,
vnconfig
—
configure vnode disks
| mount_vnd |
[-k]
[-K rounds]
[-o options]
[-S saltfile]
[-t disktype] image
vnd_dev |
| vnconfig |
[-ckluv]
[-K rounds]
[-S saltfile]
[-t disktype] vnd_dev
image |
The
vnconfig command configures vnode pseudo disk
devices. It will associate (or disassociate) the special file
vnd_dev with the regular file
image, allowing the latter to be accessed as
though it were a disk.
mount_vnd works similarly to
vnconfig, but it provides an interface that can
be used by the
fstab(5)
infrastructure, so that an
image file can be
configured to a device
node while booting.
mount_vnd defaults to the
vnd0 device.
For
fstab(5) lines with type
“ffs”, the “noauto” option must be set to prevent a
mount(8) of the FFS partitions
before the necessary vnd devices are configured. Also, the
“fs_passno” field has to be set to 0 to prevent
fsck(8) from checking the file
system for the same reasons.
mount_vnd is invoked by
mount(8) when using the following
syntax:
mount
[options] -t vnd
image
node
The options are as follows:
-
-
- -c
- vnconfig only. Configures the
device. If successful, references to
vnd_dev will access the contents of
image. This is the default
operation.
-
-
- -K
rounds
- Associate an encryption key with the device. All data will
be encrypted using the Blowfish cipher before it is written to the disk.
The user is asked for both a passphrase and the name of a salt file. The
salt file can also be specified on the command line using the
-S option. The passphrase and salt are
combined according to PKCS #5 PBKDF2 for the specified number of rounds to
generate the actual key used. rounds is a
number between 1000 and
INT_MAX. DO NOT
LOSE THE SALT FILE.
-
-
- -k
- Associate an encryption key with the device. All data will
be encrypted using the Blowfish cipher before it is written to the
disk.
-
-
- -l
- vnconfig only. List the vnd
devices and indicate which ones are in use. If a specific
vnd_dev is given, then only that one will
be described.
-
-
- -o
options
- mount_vnd only. Options are
specified with a -o flag followed by a comma
separated string of options. See the
mount(8) man page for
possible options and their meanings.
At the moment, -o is only here for
compatibility reasons, but no use is made of supplied options.
-
-
- -S
saltfile
- When -K is used, specify the
saltfile.
-
-
- -t
disktype
- Specify a disktype entry
from the disktab(5)
database. The vnd_dev will have the
sector size, sectors per track, and tracks per cylinder values of the
specified disktype. The defaults are
512-byte sectors, 100 sectors per track and 1 track per cylinder.
-
-
- -u
- vnconfig only. Unconfigures a
vnd_dev.
-
-
- -v
- vnconfig only. Print messages
to stdout describing actions taken.
- /dev/{,r}vnd*
-
Configure a CD-ROM or DVD image file as vnode disk vnd0 and mount the ISO 9660
file system contained in it:
# vnconfig vnd0 /tmp/diskimage
# mount -t cd9660 /dev/vnd0c /mnt
Configure an encrypted image file as vnode disk vnd0 and mount the FFS file
system contained in the ‘a’ partition of the disklabel. The
encryption key does not echo and must be entered every time the vnode disk is
configured.
# vnconfig -k vnd0 /tmp/cryptimg
Encryption key:
# mount /dev/vnd0a /mnt
An equivalent
fstab(5) entry is:
/tmp/cryptimg /dev/vnd0c vnd rw,noauto,-k 0 0
/dev/vnd0a /mnt ffs rw,noauto 0 0
Same as above, but now configure the vnode using PKCS #5 PBKDF2 and a salt file
with 20000 rounds:
# vnconfig -K 20000 vnd0 /tmp/cryptimg
Encryption key:
Salt file: /tmp/cryptsalt
# mount /dev/vnd0a /mnt
An equivalent
fstab(5) entry is:
/tmp/cryptimg /dev/vnd0c vnd rw,noauto,-K=20000 0 0
/dev/vnd0a /mnt ffs rw,noauto 0 0
Unmount the file system and unconfigure the vnode device:
# umount /mnt
# vnconfig -u vnd0
A sample of commands to put in
rc.local(8) in order to have
vnd images configured at boot time is listed here:
# Example for automatically configuring a vnd device on startup
echo "configuring vnd devices:"
mount /dev/vnd0c
fsck -p /dev/rvnd0a
mount /mnt
Mounting images during the first pass of
fsck(8) and
mount(8) is not possible, because
the image to be configured to a vnd itself resides on a file system that first
has to be checked and mounted.
vnd(4),
disktab(5),
fstab(5),
mount(8),
swapon(8),
umount(8)
The
mount_vnd command first appeared in
OpenBSD 4.2.
The ‘c’ partition of a vnd image should not be used. When a
superblock becomes damaged,
fsck_ffs(8) needs information
contained in the disklabel to determine the location of alternate superblocks.
This information is not available when directly using the ‘c’
partition, so checking the file system image will fail.
Swapping to vnd devices is no longer supported.
The encryption used is obsolete. Consider using
softraid(4) instead.
![[OpenBSD]](/openbsd.gif){kind=small}