FSIRAND(8)              FreeBSD System Manager's Manual             FSIRAND(8)

NAME
     fsirand - randomize inode generation numbers

SYNOPSIS
     fsirand [-b] [-f] [-p] special [special ...]

DESCRIPTION
     The fsirand utility installs random generation numbers on all the inodes
     for each file system specified on the command line by special.  This
     increases the security of NFS-exported file systems by making it
     difficult to ``guess'' filehandles.

     Note: newfs(8) now does the equivalent of fsirand itself so it is no
     longer necessary to run fsirand by hand on a new file system.  It is only
     used to re-randomize or report on an existing file system.

     The fsirand utility should only be used on an unmounted file system that
     has been checked with fsck(8) or a file system that is mounted read-only.
     The fsirand utility may be used on the root file system in single-user
     mode but the system should be rebooted via ``reboot -n'' afterwards.

OPTIONS
     The available options are as follows:

     -b      Use the default block size (usually 512 bytes) instead of the
             value gleaned from the disklabel.

     -f      Force fsirand to run even if the file system on special is not
             marked as clean.

     -p      Print the current generation numbers for all inodes instead of
             generating new ones.

SEE ALSO
     fs(5), fsck(8), newfs(8)

HISTORY
     The fsirand utility appeared in SunOS 3.x.

     This version of fsirand first appeared in OpenBSD 2.1.

     A FreeBSD version first appeared in FreeBSD 2.2.5.

AUTHORS
     Todd C. Miller <Todd.Miller@courtesan.com>

CAVEATS
     Since fsirand 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.

FreeBSD 13.1-RELEASE-p6        January 25, 1997        FreeBSD 13.1-RELEASE-p6