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.\" $Id: ssh-rand-helper.8,v 1.3 2007/01/22 01:44:53 djm Exp $
.\"
.\" Copyright (c) 2002 Damien Miller. All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
.\"
.Dd April 14, 2002
.Dt SSH-RAND-HELPER 8
.Os
.Sh NAME
.Nm ssh-rand-helper
.Nd random number gatherer for OpenSSH
.Sh SYNOPSIS
.Nm ssh-rand-hlper
.Op Fl vxXh
.Op Fl b Ar bytes
.Sh DESCRIPTION
.Nm
is a small helper program used by
.Xr ssh 1 ,
.Xr ssh-add 1 ,
.Xr ssh-agent 1 ,
.Xr ssh-keygen 1 ,
.Xr ssh-keyscan 1
and
.Xr sshd 8
to gather random numbers of cryptographic quality if the
.Xr openssl 4
library has not been configured to provide them itself.
.Pp
Normally
.Nm
will generate a strong random seed and provide it to the calling
program via standard output. If standard output is a tty,
.Nm
will instead print the seed in hexidecimal format unless told otherwise.
.Pp
.Nm
will by default gather random numbers from the system commands listed
in
.Pa /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.
.Nm
will also store seed files in
.Pa ~/.ssh/prng_seed
between executions.
.Pp
Alternately,
.Nm
may be configured at build time to collect random numbers from a
EGD/PRNGd server via a unix domain or localhost tcp socket.
.Pp
This program is not intended to be run by the end-user, so the few
commandline options are for debugging purposes only.
.Bl -tag -width Ds
.It Fl b Ar bytes
Specify the number of random bytes to include in the output.
.It Fl x
Output a hexidecimal instead of a binary seed.
.It Fl X
Force output of a binary seed, even if standard output is a tty
.It Fl v
Turn on debugging message. Multiple
.Fl v
options will increase the debugging level.
.It Fl h
Display a summary of options.
.El
.Sh AUTHORS
Damien Miller <djm@mindrot.org>
.Sh SEE ALSO
.Xr ssh 1 ,
.Xr ssh-add 1 ,
.Xr ssh-keygen 1 ,
.Xr sshd 8
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