view dropbearkey.1 @ 1715:3974f087d9c0

Disallow leading lines before the ident for server (#102) Per RFC4253 4.2 clients must be able to process other lines of data before the version string, server behavior is not defined neither with MUST/SHOULD nor with MAY. If server process up to 50 lines too - it may cause too long hanging session with invalid/evil client that consume host resources and potentially may lead to DDoS on poor embedded boxes. Let's require first line from client to be version string and fail early if it's not - matches both RFC and real OpenSSH behavior.
author Vladislav Grishenko <themiron@users.noreply.github.com>
date Mon, 15 Jun 2020 18:22:18 +0500
parents 5c8913b7464c
children
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.TH dropbearkey 1
.SH NAME
dropbearkey \- create private keys for the use with dropbear(8) or dbclient(1)
.SH SYNOPSIS
.B dropbearkey
\-t
.I type
\-f
.I file
[\-s
.IR bits ]
[\-y]
.SH DESCRIPTION
.B dropbearkey
generates a
\fIRSA\fR, \fIDSS\fR, \fIECDSA\fR, or \fIEd25519\fR
format SSH private key, and saves it to a file for the use with the
Dropbear client or server.
Note that 
some SSH implementations
use the term "DSA" rather than "DSS", they mean the same thing.
.SH OPTIONS
.TP
.B \-t \fItype
Type of key to generate.
Must be one of
.I rsa
.I ecdsa
.I ed25519
or
.IR dss .
.TP
.B \-f \fIfile
Write the secret key to the file
\fIfile\fR. For client authentication ~/.ssh/id_dropbear is loaded by default
.TP
.B \-s \fIbits
Set the key size to
.I bits
bits, should be multiple of 8 (optional). 
.TP
.B \-y
Just print the publickey and fingerprint for the private key in \fIfile\fR.
.SH NOTES
The program dropbearconvert(1) can be used to convert between Dropbear and OpenSSH key formats.
.P
Dropbear does not support encrypted keys. 
.SH EXAMPLE
generate a host-key:
 # dropbearkey -t rsa -f /etc/dropbear/dropbear_rsa_host_key

extract a public key suitable for authorized_keys from private key:
 # dropbearkey -y -f id_rsa | grep "^ssh-rsa " >> authorized_keys
.SH AUTHOR
Matt Johnston ([email protected]).
.br
Gerrit Pape ([email protected]) wrote this manual page.
.SH SEE ALSO
dropbear(8), dbclient(1), dropbearconvert(1)
.P
https://matt.ucc.asn.au/dropbear/dropbear.html