SAVE-ENTROPY(8)         FreeBSD System Manager's Manual        SAVE-ENTROPY(8)

NAME

     save-entropy - Save bits of entropy to feed /dev/random at startup

SYNOPSIS

     save-entropy

DESCRIPTION

     The save-entropy command is used to save entropy data from /dev/random to
     files in a specified output location.  The files saved are used at
     startup to provide additional entropy for /dev/random.  The output file
     will be different in every invocation until the maximum number of
     different files is reached.  (See entropy_save_num for details).  By
     default this script is invoked via cron(8) every eleven minutes
     approximately.

     This command does nothing if executed inside a jail(8).

     Three variables in /etc/rc.conf regulate the behavior of the script:

     entropy_dir
             Specify the directory for saved entropy files.  Defaults to
             /var/db/entropy.  If set to "NO" it disables caching entropy via
             cron(8).  This setting is shared with /etc/rc.d/random.

     entropy_save_sz
             Size of the entropy cache files.  Defaults to 4096.

     entropy_save_num
             Number of entropy cache files to save.  Defaults to 8.

FILES

     /etc/rc.conf

EXIT STATUS

     The save-entropy utility exits 0 on success, and >0 if an error occurs.
     Errors will be recorded in the system log.

SEE ALSO

     syslog(3), random(4), rc.conf(5), cron(8)

HISTORY

     The save-entropy command first appeared in FreeBSD 5.0.

AUTHORS

     The save-entropy command was originally written by Doug Barton
     <dougb@FreeBSD.org>.  This manual page was written by
     Fernando Apesteguia <fernape@FreeBSD.org>.

FreeBSD 15.1-STABLE-HBSD      September 18, 2023               SAVE-ENTROPY(8)