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Damien Millera8e06ce2003-11-21 23:48:55 +11001.\" $Id: ssh-rand-helper.8,v 1.2 2003/11/21 12:48:56 djm Exp $
Damien Miller32e48182002-04-14 19:27:12 +10002.\"
3.\" Copyright (c) 2002 Damien Miller. All rights reserved.
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25.Dd April 14, 2002
26.Dt SSH-RAND-HELPER 8
27.Os
28.Sh NAME
29.Nm ssh-rand-helper
30.Nd Random number gatherer for OpenSSH
31.Sh SYNOPSIS
32.Nm ssh-rand-hlper
33.Op Fl vxXh
34.Op Fl b Ar bytes
35.Sh DESCRIPTION
36.Nm
Damien Millera8e06ce2003-11-21 23:48:55 +110037is a small helper program used by
Damien Miller32e48182002-04-14 19:27:12 +100038.Xr ssh 1 ,
39.Xr ssh-add 1 ,
40.Xr ssh-agent 1 ,
41.Xr ssh-keygen 1 ,
Damien Millera8e06ce2003-11-21 23:48:55 +110042.Xr ssh-keyscan 1
Damien Miller32e48182002-04-14 19:27:12 +100043and
44.Xr sshd 8
Damien Millera8e06ce2003-11-21 23:48:55 +110045to gather random numbers of cryptographic quality if the
Damien Miller32e48182002-04-14 19:27:12 +100046.Xr openssl 4
47library has not been configured to provide them itself.
48.Pp
Damien Millera8e06ce2003-11-21 23:48:55 +110049Normally
Damien Miller32e48182002-04-14 19:27:12 +100050.Nm
51will generate a strong random seed and provide it to the calling
Damien Millera8e06ce2003-11-21 23:48:55 +110052program via standard output. If standard output is a tty,
Damien Miller32e48182002-04-14 19:27:12 +100053.Nm
54will instead print the seed in hexidecimal format unless told otherwise.
55.Pp
56.Nm
57will by default gather random numbers from the system commands listed
58in
59.Pa /etc/ssh/ssh_prng_cmds .
Damien Millera8e06ce2003-11-21 23:48:55 +110060The output of each of the commands listed will be hashed and used to
61generate a random seed for the calling program.
Damien Miller32e48182002-04-14 19:27:12 +100062.Nm
Damien Millera8e06ce2003-11-21 23:48:55 +110063will also store seed files in
Damien Miller32e48182002-04-14 19:27:12 +100064.Pa ~/.ssh/prng_seed
65between executions.
66.Pp
Damien Millera8e06ce2003-11-21 23:48:55 +110067Alternately,
Damien Miller32e48182002-04-14 19:27:12 +100068.Nm
Damien Millera8e06ce2003-11-21 23:48:55 +110069may be configured at build time to collect random numbers from a
Damien Miller32e48182002-04-14 19:27:12 +100070EGD/PRNGd server via a unix domain or localhost tcp socket.
71.Pp
Damien Millera8e06ce2003-11-21 23:48:55 +110072This program is not intended to be run by the end-user, so the few
Damien Miller32e48182002-04-14 19:27:12 +100073commandline options are for debugging purposes only.
74.Bl -tag -width Ds
75.It Fl b Ar bytes
76Specify the number of random bytes to include in the output.
77.It Fl x
78Output a hexidecimal instead of a binary seed.
79.It Fl X
80Force output of a binary seed, even if standard output is a tty
81.It Fl v
82Turn on debugging message. Multiple
83.Fl v
84options will increase the debugging level.
85.Fl h
86Display a summary of options.
87.El
88.Sh AUTHORS
89Damien Miller <djm@mindrot.org>
90.Sh SEE ALSO
91.Xr ssh 1 ,
92.Xr ssh-add 1 ,
93.Xr ssh-keygen 1 ,
94.Xr sshd 8