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 gener-
ator 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)