trusty (1) mcookie.1.gz

Provided by: util-linux_2.20.1-5.1ubuntu20.9_amd64 bug

NAME
       mcookie - generate magic cookies for xauth


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/.