.\" $OpenBSD: fsirand.8,v 1.27 2003/07/30 22:29:32 millert Exp $
.\"
.\" Copyright (c) 1997 Todd C. Miller <Todd.Miller@courtesan.com>
.\"
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.\" purpose with or without fee is hereby granted, provided that the above
.\" copyright notice and this permission notice appear in all copies.
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.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
.\"
.Dd January 25, 1997
.Dt FSIRAND 8
.Os
.Sh NAME
.Nm fsirand
.Nd randomize inode generation numbers
.Sh SYNOPSIS
.Nm fsirand
.Op Fl b
.Op Fl f
.Op Fl p
.Ar special
.Op Ar ...
.Sh DESCRIPTION
The
.Nm
command installs random generation numbers on all the inodes for
each filesystem specified on the command line by
.Ar special .
This increases the security of NFS-exported filesystems by making
it difficult to
.Dq guess
filehandles.
.Pp
.Em Note :
.Xr newfs 8
now does the equivalent of
.Nm
itself so it is no longer necessary to
run
.Nm
by hand on a new filesystem.
It is only used to re-randomize or report on an existing filesystem.
.Pp
.Nm
should only be used on an unmounted filesystem that
has been checked with
.Xr fsck 8
or a filesystem that is mounted read-only.
.Nm
may be used on the root filesystem in single-user mode
but the system should be rebooted via
.Dq reboot -n
afterwards.
.Pp
The options are as follows:
.Bl -tag -width Ds
.It Fl b
Use the default block size (usually 512 bytes) instead
of the value gleaned from the disklabel.
.It Fl f
Force
.Nm
to run even if the filesystem on
.Ar special
is not marked as clean.
.It Fl p
Print the current generation numbers for all inodes instead of
generating new ones.
.El
.Sh SEE ALSO
.Xr fs 5 ,
.Xr fsck 8 ,
.Xr newfs 8 ,
.Xr reboot 8
.Sh HISTORY
The
.Nm
command appeared in SunOS 3.x.
This version of
.Nm
first appeared in
.Ox 2.1 .
.Sh AUTHORS
.An Todd C. Miller
.Sh CAVEATS
Since
.Nm
allocates enough memory to hold all the inodes in
a given cylinder group, it may use a large amount
of memory for large disks with few cylinder groups.