ssh-rand-helper.8   [plain text]


.\" $Id: ssh-rand-helper.8,v 1.2 2003/11/21 12:48:56 djm Exp $
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.\" Copyright (c) 2002 Damien Miller.  All rights reserved.
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.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.
.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