ssh-rand-helper.0   [plain text]

SSH-RAND-HELPER(8)      OpenBSD System Manager's Manual     SSH-RAND-HELPER(8)

     ssh-rand-helper - random number gatherer for OpenSSH

     ssh-rand-hlper [-vxXh] [-b bytes]

     ssh-rand-helper is a small helper program used by ssh(1), ssh-add(1),
     ssh-agent(1), ssh-keygen(1), ssh-keyscan(1) and sshd(8) to gather random
     numbers of cryptographic quality if the openssl(4) library has not been
     configured to provide them itself.

     Normally ssh-rand-helper will generate a strong random seed and provide
     it to the calling program via standard output. If standard output is a
     tty, ssh-rand-helper will instead print the seed in hexidecimal format
     unless told otherwise.

     ssh-rand-helper will by default gather random numbers from the system
     commands listed in /etc/ssh/ssh_prng_cmds.  The output of each of the
     commands listed will be hashed and used to generate a random seed for the
     calling program.  ssh-rand-helper will also store seed files in
     ~/.ssh/prng_seed between executions.

     Alternately, ssh-rand-helper may be configured at build time to collect
     random numbers from a EGD/PRNGd server via a unix domain or localhost tcp

     This program is not intended to be run by the end-user, so the few
     commandline options are for debugging purposes only.

     -b bytes
             Specify the number of random bytes to include in the output.

     -x      Output a hexidecimal instead of a binary seed.

     -X      Force output of a binary seed, even if standard output is a tty

     -v      Turn on debugging message. Multiple -v options will increase the
             debugging level.

     -h      Display a summary of options.

     Damien Miller <>

     ssh(1), ssh-add(1), ssh-keygen(1), sshd(8)

OpenBSD 4.8                     April 14, 2002                     OpenBSD 4.8