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

# NAME

`fsirand` — randomize inode generation numbers

# SYNOPSIS

`fsirand` | [`-bfp`] special ...

# DESCRIPTION

The `fsirand` command installs random generation numbers on all the inodes for each filesystem specified on the command line by special. This increases the security of NFS-exported filesystems 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 filesystem. It is only used to re-randomize or report on an existing filesystem.

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

The 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 filesystem 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), reboot(8)

# HISTORY

The `fsirand` command appeared in SunOS 3.x. This version of `fsirand` first appeared in OpenBSD 2.1.

# AUTHORS

Todd C. Miller

# 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.

January 25, 2019 | Debian