| .\" mcookie.1 -- |
| .\" Public Domain 1995 Rickard E. Faith (faith@cs.unc.edu) |
| .TH MCOOKIE 1 "25 September 1995" "" "Linux Programmer's Manual" |
| .SH NAME |
| mcookie \- generate magic cookies for xauth |
| .SH SYNOPSIS |
| .B mcookie |
| .RB [ \-v ] |
| .RB [ \-f |
| .IR filename ] |
| .SH DESCRIPTION |
| .B mcookie |
| generates a 128-bit random hexadecimal number for use with the X authority |
| system. Typical usage: |
| .RS |
| xauth add :0 . `mcookie` |
| .RE |
| .PP |
| 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 |
| .B \-f |
| is specified), and several bytes of information from the first of the |
| following devices which is present: |
| .IR /dev/random , |
| .IR /dev/urandom , |
| files in |
| .IR /proc , |
| .IR /dev/audio . |
| .SH 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., |
| .I /dev/random |
| under Linux). |
| .PP |
| It is assumed that none of the devices opened will block. |
| .SH FILES |
| .I /dev/random |
| .br |
| .I /dev/urandom |
| .br |
| .I /dev/audio |
| .br |
| .I /proc/stat |
| .br |
| .I /proc/loadavg |
| .SH "SEE ALSO" |
| .BR X (1), |
| .BR xauth (1), |
| .BR md5sum (1) |
| .SH 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/. |