HardenedBSD/crypto/openssh/ssh-rand-helper.8
Dag-Erling Smørgrav d4af9e693f Upgrade to OpenSSH 5.1p1.
I have worked hard to reduce diffs against the vendor branch.  One
notable change in that respect is that we no longer prefer DSA over
RSA - the reasons for doing so went away years ago.  This may cause
some surprises, as ssh will warn about unknown host keys even for
hosts whose keys haven't changed.

MFC after:	6 weeks
2008-08-01 02:48:36 +00:00

95 lines
3.0 KiB
Groff

.\" $Id: ssh-rand-helper.8,v 1.3 2007/01/22 01:44:53 djm Exp $
.\"
.\" 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.
.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