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.

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.