1.\" $NetBSD: ssh-keysign.8,v 1.15 2024/07/08 22:33:44 christos Exp $ 2.\" $OpenBSD: ssh-keysign.8,v 1.18 2024/06/17 08:30:29 djm Exp $ 3.\" 4.\" Copyright (c) 2002 Markus Friedl. All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 15.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25.\" 26.Dd June 17 2024 27.Dt SSH-KEYSIGN 8 28.Os 29.Sh NAME 30.Nm ssh-keysign 31.Nd OpenSSH helper for host-based authentication 32.Sh SYNOPSIS 33.Nm 34.Sh DESCRIPTION 35.Nm 36is used by 37.Xr ssh 1 38to access the local host keys and generate the digital signature 39required during host-based authentication. 40.Pp 41.Nm 42is disabled by default and can only be enabled in the 43global client configuration file 44.Pa /etc/ssh/ssh_config 45by setting 46.Cm EnableSSHKeysign 47to 48.Dq yes . 49.Pp 50.Nm 51is not intended to be invoked by the user, but from 52.Xr ssh 1 . 53See 54.Xr ssh 1 55and 56.Xr sshd 8 57for more information about host-based authentication. 58.Sh FILES 59.Bl -tag -width Ds -compact 60.It Pa /etc/ssh/ssh_config 61Controls whether 62.Nm 63is enabled. 64.Pp 65.It Pa /etc/ssh/ssh_host_ecdsa_key 66.It Pa /etc/ssh/ssh_host_ed25519_key 67.It Pa /etc/ssh/ssh_host_rsa_key 68These files contain the private parts of the host keys used to 69generate the digital signature. 70They should be owned by root, readable only by root, and not 71accessible to others. 72Since they are readable only by root, 73.Nm 74must be set-uid root if host-based authentication is used. 75.Pp 76.It Pa /etc/ssh/ssh_host_ecdsa_key-cert.pub 77.It Pa /etc/ssh/ssh_host_ed25519_key-cert.pub 78.It Pa /etc/ssh/ssh_host_rsa_key-cert.pub 79If these files exist, they are assumed to contain public certificate 80information corresponding with the private keys above. 81.El 82.Sh SEE ALSO 83.Xr ssh 1 , 84.Xr ssh-keygen 1 , 85.Xr ssh_config 5 , 86.Xr sshd 8 87.Sh HISTORY 88.Nm 89first appeared in 90.Ox 3.2 . 91.Sh AUTHORS 92.An Markus Friedl Aq Mt markus@openbsd.org 93