MCOOKIE(1)                                          Linux Programmer's Manual                                         MCOOKIE(1)



NAME
       mcookie - generate magic cookies for xauth

SYNOPSIS
       mcookie [-v] [-f filename]

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 informa-
       tion: the current time, the process id, the parent process id, the contents of an input file (if -f  is  specified),  and
       several  bytes  of information from the first of the following devices which is present: /dev/random, /dev/urandom, files
       in /proc, /dev/audio.

BUGS
       The entropy in the generated 128-bit is probably quite small (and, therefore, vulnerable to attack) unless a  non-pseudo-
       random 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-ng package and is available from ftp://ftp.kernel.org/pub/linux/utils/util-
       linux-ng/.



                                                        25 September 1995                                             MCOOKIE(1)