mcookie

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 information: 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-pseudorandom number  gen‐
       erator 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 avail‐
       able from ftp://ftp.kernel.org/pub/linux/utils/util-linux-ng/.



                               25 September 1995                    MCOOKIE(1)