Manual Reference Pages  - MCOOKIE (1)

NAME

mcookie - generate magic cookies for xauth

CONTENTS

Synopsis
Description
Options
Bugs
Files
Availability

SYNOPSIS

mcookie [options]

DESCRIPTION

mcookie generates a 128-bit random hexadecimal number for use with the X authority system. Typical usage:
xauth add :0 . ‘mcookie‘

The "random" number generated is actually the output of the MD5 message digest fed with various pieces of random information: the current time, the process id, the parent process id, and optionally the contents of an input file. and several bytes of information from the first of the following devices which is present: /dev/random, /dev/urandom, files in /proc, /dev/audio.

OPTIONS

-f, --file=FILE
  Use file as a macig cookie seed. When file is defined as ‘-’ character input is read from stdin.
-v, --verbose
  Explain what is being done.
-V, --version
  Output version information and exit.
-h, --help Display this help and exit.

BUGS

The entropy in the generated 128-bit is probably quite small (and, therefore, vulnerable to attack) unless a non-pseudorandom number generator is used (e.g., /dev/random under Linux).

It is assumed that none of the devices opened will block.

FILES

/dev/random
/dev/urandom
/dev/audio
/proc/stat
/proc/loadavg

SEE ALSO

X(1), xauth(1), md5sum(1)

AVAILABILITY

The mcookie command is part of the util-linux package and is available from ftp://ftp.kernel.org/pub/linux/utils/util-linux/.


util-linux MCOOKIE (1) June 2011
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