openssh/sshd.8

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.\" -*- nroff -*-
.\"
.\" Author: Tatu Ylonen <ylo@cs.hut.fi>
.\" Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
.\" All rights reserved
.\"
- (djm) Merge OpenBSD changes: - markus@cvs.openbsd.org 2000/09/05 02:59:57 [session.c] print hostname (not hushlogin) - markus@cvs.openbsd.org 2000/09/05 13:18:48 [authfile.c ssh-add.c] enable ssh-add -d for DSA keys - markus@cvs.openbsd.org 2000/09/05 13:20:49 [sftp-server.c] cleanup - markus@cvs.openbsd.org 2000/09/06 03:46:41 [authfile.h] prototype - deraadt@cvs.openbsd.org 2000/09/07 14:27:56 [ALL] cleanup copyright notices on all files. I have attempted to be accurate with the details. everything is now under Tatu's licence (which I copied from his readme), and/or the core-sdi bsd-ish thing for deattack, or various openbsd developers under a 2-term bsd licence. We're not changing any rules, just being accurate. - markus@cvs.openbsd.org 2000/09/07 14:40:30 [channels.c channels.h clientloop.c serverloop.c ssh.c] cleanup window and packet sizes for ssh2 flow control; ok niels - markus@cvs.openbsd.org 2000/09/07 14:53:00 [scp.c] typo - markus@cvs.openbsd.org 2000/09/07 15:13:37 [auth-options.c auth-options.h auth-rh-rsa.c auth-rsa.c auth.c] [authfile.h canohost.c channels.h compat.c hostfile.h log.c match.h] [pty.c readconf.c] some more Copyright fixes - markus@cvs.openbsd.org 2000/09/08 03:02:51 [README.openssh2] bye bye - deraadt@cvs.openbsd.org 2000/09/11 18:38:33 [LICENCE cipher.c] a few more comments about it being ARC4 not RC4 - markus@cvs.openbsd.org 2000/09/12 14:53:11 [log-client.c log-server.c log.c ssh.1 ssh.c ssh.h sshd.8 sshd.c] multiple debug levels - markus@cvs.openbsd.org 2000/09/14 14:25:15 [clientloop.c] typo - deraadt@cvs.openbsd.org 2000/09/15 01:13:51 [ssh-agent.c] check return value for setenv(3) for failure, and deal appropriately
2000-09-16 02:29:08 +00:00
.\" As far as I am concerned, the code I have written for this software
.\" can be used freely for any purpose. Any derived versions of this
.\" software must be clearly marked as such, and if the derived work is
.\" incompatible with the protocol description in the RFC file, it must be
.\" called by a name other than "ssh" or "Secure Shell".
.\"
.\" Copyright (c) 1999,2000 Markus Friedl. All rights reserved.
.\" Copyright (c) 1999 Aaron Campbell. All rights reserved.
.\" Copyright (c) 1999 Theo de Raadt. All rights reserved.
- (djm) Merge OpenBSD changes: - markus@cvs.openbsd.org 2000/09/05 02:59:57 [session.c] print hostname (not hushlogin) - markus@cvs.openbsd.org 2000/09/05 13:18:48 [authfile.c ssh-add.c] enable ssh-add -d for DSA keys - markus@cvs.openbsd.org 2000/09/05 13:20:49 [sftp-server.c] cleanup - markus@cvs.openbsd.org 2000/09/06 03:46:41 [authfile.h] prototype - deraadt@cvs.openbsd.org 2000/09/07 14:27:56 [ALL] cleanup copyright notices on all files. I have attempted to be accurate with the details. everything is now under Tatu's licence (which I copied from his readme), and/or the core-sdi bsd-ish thing for deattack, or various openbsd developers under a 2-term bsd licence. We're not changing any rules, just being accurate. - markus@cvs.openbsd.org 2000/09/07 14:40:30 [channels.c channels.h clientloop.c serverloop.c ssh.c] cleanup window and packet sizes for ssh2 flow control; ok niels - markus@cvs.openbsd.org 2000/09/07 14:53:00 [scp.c] typo - markus@cvs.openbsd.org 2000/09/07 15:13:37 [auth-options.c auth-options.h auth-rh-rsa.c auth-rsa.c auth.c] [authfile.h canohost.c channels.h compat.c hostfile.h log.c match.h] [pty.c readconf.c] some more Copyright fixes - markus@cvs.openbsd.org 2000/09/08 03:02:51 [README.openssh2] bye bye - deraadt@cvs.openbsd.org 2000/09/11 18:38:33 [LICENCE cipher.c] a few more comments about it being ARC4 not RC4 - markus@cvs.openbsd.org 2000/09/12 14:53:11 [log-client.c log-server.c log.c ssh.1 ssh.c ssh.h sshd.8 sshd.c] multiple debug levels - markus@cvs.openbsd.org 2000/09/14 14:25:15 [clientloop.c] typo - deraadt@cvs.openbsd.org 2000/09/15 01:13:51 [ssh-agent.c] check return value for setenv(3) for failure, and deal appropriately
2000-09-16 02:29:08 +00:00
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
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.\"
- (djm) Merge OpenBSD changes: - markus@cvs.openbsd.org 2000/09/05 02:59:57 [session.c] print hostname (not hushlogin) - markus@cvs.openbsd.org 2000/09/05 13:18:48 [authfile.c ssh-add.c] enable ssh-add -d for DSA keys - markus@cvs.openbsd.org 2000/09/05 13:20:49 [sftp-server.c] cleanup - markus@cvs.openbsd.org 2000/09/06 03:46:41 [authfile.h] prototype - deraadt@cvs.openbsd.org 2000/09/07 14:27:56 [ALL] cleanup copyright notices on all files. I have attempted to be accurate with the details. everything is now under Tatu's licence (which I copied from his readme), and/or the core-sdi bsd-ish thing for deattack, or various openbsd developers under a 2-term bsd licence. We're not changing any rules, just being accurate. - markus@cvs.openbsd.org 2000/09/07 14:40:30 [channels.c channels.h clientloop.c serverloop.c ssh.c] cleanup window and packet sizes for ssh2 flow control; ok niels - markus@cvs.openbsd.org 2000/09/07 14:53:00 [scp.c] typo - markus@cvs.openbsd.org 2000/09/07 15:13:37 [auth-options.c auth-options.h auth-rh-rsa.c auth-rsa.c auth.c] [authfile.h canohost.c channels.h compat.c hostfile.h log.c match.h] [pty.c readconf.c] some more Copyright fixes - markus@cvs.openbsd.org 2000/09/08 03:02:51 [README.openssh2] bye bye - deraadt@cvs.openbsd.org 2000/09/11 18:38:33 [LICENCE cipher.c] a few more comments about it being ARC4 not RC4 - markus@cvs.openbsd.org 2000/09/12 14:53:11 [log-client.c log-server.c log.c ssh.1 ssh.c ssh.h sshd.8 sshd.c] multiple debug levels - markus@cvs.openbsd.org 2000/09/14 14:25:15 [clientloop.c] typo - deraadt@cvs.openbsd.org 2000/09/15 01:13:51 [ssh-agent.c] check return value for setenv(3) for failure, and deal appropriately
2000-09-16 02:29:08 +00:00
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
.\" $OpenBSD: sshd.8,v 1.157 2001/12/19 07:18:56 deraadt Exp $
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.Dd September 25, 1999
.Dt SSHD 8
.Os
.Sh NAME
.Nm sshd
.Nd OpenSSH SSH daemon
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.Sh SYNOPSIS
.Nm sshd
.Op Fl deiqtD46
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.Op Fl b Ar bits
.Op Fl f Ar config_file
.Op Fl g Ar login_grace_time
.Op Fl h Ar host_key_file
.Op Fl k Ar key_gen_time
.Op Fl o Ar option
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.Op Fl p Ar port
.Op Fl u Ar len
.Sh DESCRIPTION
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.Nm
(SSH Daemon) is the daemon program for
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.Xr ssh 1 .
Together these programs replace rlogin and rsh, and
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provide secure encrypted communications between two untrusted hosts
over an insecure network.
The programs are intended to be as easy to
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install and use as possible.
.Pp
.Nm
is the daemon that listens for connections from clients.
It is normally started at boot from
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.Pa /etc/rc .
It forks a new
daemon for each incoming connection.
The forked daemons handle
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key exchange, encryption, authentication, command execution,
and data exchange.
- Remove references to SSLeay. - Big OpenBSD CVS update - markus@cvs.openbsd.org [clientloop.c] - typo [session.c] - update proctitle on pty alloc/dealloc, e.g. w/ windows client [session.c] - update proctitle for proto 1, too [channels.h nchan.c serverloop.c session.c sshd.c] - use c-style comments - deraadt@cvs.openbsd.org [scp.c] - more atomicio - markus@cvs.openbsd.org [channels.c] - set O_NONBLOCK [ssh.1] - update AUTHOR [readconf.c ssh-keygen.c ssh.h] - default DSA key file ~/.ssh/id_dsa [clientloop.c] - typo, rm verbose debug - deraadt@cvs.openbsd.org [ssh-keygen.1] - document DSA use of ssh-keygen [sshd.8] - a start at describing what i understand of the DSA side [ssh-keygen.1] - document -X and -x [ssh-keygen.c] - simplify usage - markus@cvs.openbsd.org [sshd.8] - there is no rhosts_dsa [ssh-keygen.1] - document -y, update -X,-x [nchan.c] - fix close for non-open ssh1 channels [servconf.c servconf.h ssh.h sshd.8 sshd.c ] - s/DsaKey/HostDSAKey/, document option [sshconnect2.c] - respect number_of_password_prompts [channels.c channels.h servconf.c servconf.h session.c sshd.8] - GatewayPorts for sshd, ok deraadt@ [ssh-add.1 ssh-agent.1 ssh.1] - more doc on: DSA, id_dsa, known_hosts2, authorized_keys2 [ssh.1] - more info on proto 2 [sshd.8] - sync AUTHOR w/ ssh.1 [key.c key.h sshconnect.c] - print key type when talking about host keys [packet.c] - clear padding in ssh2 [dsa.c key.c radix.c ssh.h sshconnect1.c uuencode.c uuencode.h] - replace broken uuencode w/ libc b64_ntop [auth2.c] - log failure before sending the reply [key.c radix.c uuencode.c] - remote trailing comments before calling __b64_pton [auth2.c readconf.c readconf.h servconf.c servconf.h ssh.1] [sshconnect2.c sshd.8] - add DSAAuthetication option to ssh/sshd, document SSH2 in sshd.8 - Bring in b64_ntop and b64_pton from OpenBSD libc (bsd-base64.[ch])
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This implementation of
.Nm
supports both SSH protocol version 1 and 2 simultaneously.
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.Nm
works as follows.
- Remove references to SSLeay. - Big OpenBSD CVS update - markus@cvs.openbsd.org [clientloop.c] - typo [session.c] - update proctitle on pty alloc/dealloc, e.g. w/ windows client [session.c] - update proctitle for proto 1, too [channels.h nchan.c serverloop.c session.c sshd.c] - use c-style comments - deraadt@cvs.openbsd.org [scp.c] - more atomicio - markus@cvs.openbsd.org [channels.c] - set O_NONBLOCK [ssh.1] - update AUTHOR [readconf.c ssh-keygen.c ssh.h] - default DSA key file ~/.ssh/id_dsa [clientloop.c] - typo, rm verbose debug - deraadt@cvs.openbsd.org [ssh-keygen.1] - document DSA use of ssh-keygen [sshd.8] - a start at describing what i understand of the DSA side [ssh-keygen.1] - document -X and -x [ssh-keygen.c] - simplify usage - markus@cvs.openbsd.org [sshd.8] - there is no rhosts_dsa [ssh-keygen.1] - document -y, update -X,-x [nchan.c] - fix close for non-open ssh1 channels [servconf.c servconf.h ssh.h sshd.8 sshd.c ] - s/DsaKey/HostDSAKey/, document option [sshconnect2.c] - respect number_of_password_prompts [channels.c channels.h servconf.c servconf.h session.c sshd.8] - GatewayPorts for sshd, ok deraadt@ [ssh-add.1 ssh-agent.1 ssh.1] - more doc on: DSA, id_dsa, known_hosts2, authorized_keys2 [ssh.1] - more info on proto 2 [sshd.8] - sync AUTHOR w/ ssh.1 [key.c key.h sshconnect.c] - print key type when talking about host keys [packet.c] - clear padding in ssh2 [dsa.c key.c radix.c ssh.h sshconnect1.c uuencode.c uuencode.h] - replace broken uuencode w/ libc b64_ntop [auth2.c] - log failure before sending the reply [key.c radix.c uuencode.c] - remote trailing comments before calling __b64_pton [auth2.c readconf.c readconf.h servconf.c servconf.h ssh.1] [sshconnect2.c sshd.8] - add DSAAuthetication option to ssh/sshd, document SSH2 in sshd.8 - Bring in b64_ntop and b64_pton from OpenBSD libc (bsd-base64.[ch])
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.Pp
.Ss SSH protocol version 1
.Pp
Each host has a host-specific RSA key
(normally 1024 bits) used to identify the host.
Additionally, when
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the daemon starts, it generates a server RSA key (normally 768 bits).
This key is normally regenerated every hour if it has been used, and
is never stored on disk.
.Pp
Whenever a client connects the daemon responds with its public
host and server keys.
The client compares the
- Remove references to SSLeay. - Big OpenBSD CVS update - markus@cvs.openbsd.org [clientloop.c] - typo [session.c] - update proctitle on pty alloc/dealloc, e.g. w/ windows client [session.c] - update proctitle for proto 1, too [channels.h nchan.c serverloop.c session.c sshd.c] - use c-style comments - deraadt@cvs.openbsd.org [scp.c] - more atomicio - markus@cvs.openbsd.org [channels.c] - set O_NONBLOCK [ssh.1] - update AUTHOR [readconf.c ssh-keygen.c ssh.h] - default DSA key file ~/.ssh/id_dsa [clientloop.c] - typo, rm verbose debug - deraadt@cvs.openbsd.org [ssh-keygen.1] - document DSA use of ssh-keygen [sshd.8] - a start at describing what i understand of the DSA side [ssh-keygen.1] - document -X and -x [ssh-keygen.c] - simplify usage - markus@cvs.openbsd.org [sshd.8] - there is no rhosts_dsa [ssh-keygen.1] - document -y, update -X,-x [nchan.c] - fix close for non-open ssh1 channels [servconf.c servconf.h ssh.h sshd.8 sshd.c ] - s/DsaKey/HostDSAKey/, document option [sshconnect2.c] - respect number_of_password_prompts [channels.c channels.h servconf.c servconf.h session.c sshd.8] - GatewayPorts for sshd, ok deraadt@ [ssh-add.1 ssh-agent.1 ssh.1] - more doc on: DSA, id_dsa, known_hosts2, authorized_keys2 [ssh.1] - more info on proto 2 [sshd.8] - sync AUTHOR w/ ssh.1 [key.c key.h sshconnect.c] - print key type when talking about host keys [packet.c] - clear padding in ssh2 [dsa.c key.c radix.c ssh.h sshconnect1.c uuencode.c uuencode.h] - replace broken uuencode w/ libc b64_ntop [auth2.c] - log failure before sending the reply [key.c radix.c uuencode.c] - remote trailing comments before calling __b64_pton [auth2.c readconf.c readconf.h servconf.c servconf.h ssh.1] [sshconnect2.c sshd.8] - add DSAAuthetication option to ssh/sshd, document SSH2 in sshd.8 - Bring in b64_ntop and b64_pton from OpenBSD libc (bsd-base64.[ch])
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RSA host key against its own database to verify that it has not changed.
The client then generates a 256 bit random number.
It encrypts this
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random number using both the host key and the server key, and sends
the encrypted number to the server.
Both sides then use this
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random number as a session key which is used to encrypt all further
communications in the session.
The rest of the session is encrypted
using a conventional cipher, currently Blowfish or 3DES, with 3DES
being used by default.
The client selects the encryption algorithm
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to use from those offered by the server.
.Pp
Next, the server and the client enter an authentication dialog.
The client tries to authenticate itself using
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.Pa .rhosts
authentication,
.Pa .rhosts
authentication combined with RSA host
authentication, RSA challenge-response authentication, or password
based authentication.
.Pp
Rhosts authentication is normally disabled
because it is fundamentally insecure, but can be enabled in the server
configuration file if desired.
System security is not improved unless
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.Xr rshd 8 ,
.Xr rlogind 8 ,
and
.Xr rexecd 8
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are disabled (thus completely disabling
.Xr rlogin 1
and
.Xr rsh 1
into the machine).
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.Pp
- Remove references to SSLeay. - Big OpenBSD CVS update - markus@cvs.openbsd.org [clientloop.c] - typo [session.c] - update proctitle on pty alloc/dealloc, e.g. w/ windows client [session.c] - update proctitle for proto 1, too [channels.h nchan.c serverloop.c session.c sshd.c] - use c-style comments - deraadt@cvs.openbsd.org [scp.c] - more atomicio - markus@cvs.openbsd.org [channels.c] - set O_NONBLOCK [ssh.1] - update AUTHOR [readconf.c ssh-keygen.c ssh.h] - default DSA key file ~/.ssh/id_dsa [clientloop.c] - typo, rm verbose debug - deraadt@cvs.openbsd.org [ssh-keygen.1] - document DSA use of ssh-keygen [sshd.8] - a start at describing what i understand of the DSA side [ssh-keygen.1] - document -X and -x [ssh-keygen.c] - simplify usage - markus@cvs.openbsd.org [sshd.8] - there is no rhosts_dsa [ssh-keygen.1] - document -y, update -X,-x [nchan.c] - fix close for non-open ssh1 channels [servconf.c servconf.h ssh.h sshd.8 sshd.c ] - s/DsaKey/HostDSAKey/, document option [sshconnect2.c] - respect number_of_password_prompts [channels.c channels.h servconf.c servconf.h session.c sshd.8] - GatewayPorts for sshd, ok deraadt@ [ssh-add.1 ssh-agent.1 ssh.1] - more doc on: DSA, id_dsa, known_hosts2, authorized_keys2 [ssh.1] - more info on proto 2 [sshd.8] - sync AUTHOR w/ ssh.1 [key.c key.h sshconnect.c] - print key type when talking about host keys [packet.c] - clear padding in ssh2 [dsa.c key.c radix.c ssh.h sshconnect1.c uuencode.c uuencode.h] - replace broken uuencode w/ libc b64_ntop [auth2.c] - log failure before sending the reply [key.c radix.c uuencode.c] - remote trailing comments before calling __b64_pton [auth2.c readconf.c readconf.h servconf.c servconf.h ssh.1] [sshconnect2.c sshd.8] - add DSAAuthetication option to ssh/sshd, document SSH2 in sshd.8 - Bring in b64_ntop and b64_pton from OpenBSD libc (bsd-base64.[ch])
2000-05-07 02:03:14 +00:00
.Ss SSH protocol version 2
.Pp
Version 2 works similarly:
Each host has a host-specific key (RSA or DSA) used to identify the host.
- Remove references to SSLeay. - Big OpenBSD CVS update - markus@cvs.openbsd.org [clientloop.c] - typo [session.c] - update proctitle on pty alloc/dealloc, e.g. w/ windows client [session.c] - update proctitle for proto 1, too [channels.h nchan.c serverloop.c session.c sshd.c] - use c-style comments - deraadt@cvs.openbsd.org [scp.c] - more atomicio - markus@cvs.openbsd.org [channels.c] - set O_NONBLOCK [ssh.1] - update AUTHOR [readconf.c ssh-keygen.c ssh.h] - default DSA key file ~/.ssh/id_dsa [clientloop.c] - typo, rm verbose debug - deraadt@cvs.openbsd.org [ssh-keygen.1] - document DSA use of ssh-keygen [sshd.8] - a start at describing what i understand of the DSA side [ssh-keygen.1] - document -X and -x [ssh-keygen.c] - simplify usage - markus@cvs.openbsd.org [sshd.8] - there is no rhosts_dsa [ssh-keygen.1] - document -y, update -X,-x [nchan.c] - fix close for non-open ssh1 channels [servconf.c servconf.h ssh.h sshd.8 sshd.c ] - s/DsaKey/HostDSAKey/, document option [sshconnect2.c] - respect number_of_password_prompts [channels.c channels.h servconf.c servconf.h session.c sshd.8] - GatewayPorts for sshd, ok deraadt@ [ssh-add.1 ssh-agent.1 ssh.1] - more doc on: DSA, id_dsa, known_hosts2, authorized_keys2 [ssh.1] - more info on proto 2 [sshd.8] - sync AUTHOR w/ ssh.1 [key.c key.h sshconnect.c] - print key type when talking about host keys [packet.c] - clear padding in ssh2 [dsa.c key.c radix.c ssh.h sshconnect1.c uuencode.c uuencode.h] - replace broken uuencode w/ libc b64_ntop [auth2.c] - log failure before sending the reply [key.c radix.c uuencode.c] - remote trailing comments before calling __b64_pton [auth2.c readconf.c readconf.h servconf.c servconf.h ssh.1] [sshconnect2.c sshd.8] - add DSAAuthetication option to ssh/sshd, document SSH2 in sshd.8 - Bring in b64_ntop and b64_pton from OpenBSD libc (bsd-base64.[ch])
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However, when the daemon starts, it does not generate a server key.
Forward security is provided through a Diffie-Hellman key agreement.
This key agreement results in a shared session key.
.Pp
The rest of the session is encrypted using a symmetric cipher, currently
128 bit AES, Blowfish, 3DES, CAST128, Arcfour, 192 bit AES, or 256 bit AES.
- Remove references to SSLeay. - Big OpenBSD CVS update - markus@cvs.openbsd.org [clientloop.c] - typo [session.c] - update proctitle on pty alloc/dealloc, e.g. w/ windows client [session.c] - update proctitle for proto 1, too [channels.h nchan.c serverloop.c session.c sshd.c] - use c-style comments - deraadt@cvs.openbsd.org [scp.c] - more atomicio - markus@cvs.openbsd.org [channels.c] - set O_NONBLOCK [ssh.1] - update AUTHOR [readconf.c ssh-keygen.c ssh.h] - default DSA key file ~/.ssh/id_dsa [clientloop.c] - typo, rm verbose debug - deraadt@cvs.openbsd.org [ssh-keygen.1] - document DSA use of ssh-keygen [sshd.8] - a start at describing what i understand of the DSA side [ssh-keygen.1] - document -X and -x [ssh-keygen.c] - simplify usage - markus@cvs.openbsd.org [sshd.8] - there is no rhosts_dsa [ssh-keygen.1] - document -y, update -X,-x [nchan.c] - fix close for non-open ssh1 channels [servconf.c servconf.h ssh.h sshd.8 sshd.c ] - s/DsaKey/HostDSAKey/, document option [sshconnect2.c] - respect number_of_password_prompts [channels.c channels.h servconf.c servconf.h session.c sshd.8] - GatewayPorts for sshd, ok deraadt@ [ssh-add.1 ssh-agent.1 ssh.1] - more doc on: DSA, id_dsa, known_hosts2, authorized_keys2 [ssh.1] - more info on proto 2 [sshd.8] - sync AUTHOR w/ ssh.1 [key.c key.h sshconnect.c] - print key type when talking about host keys [packet.c] - clear padding in ssh2 [dsa.c key.c radix.c ssh.h sshconnect1.c uuencode.c uuencode.h] - replace broken uuencode w/ libc b64_ntop [auth2.c] - log failure before sending the reply [key.c radix.c uuencode.c] - remote trailing comments before calling __b64_pton [auth2.c readconf.c readconf.h servconf.c servconf.h ssh.1] [sshconnect2.c sshd.8] - add DSAAuthetication option to ssh/sshd, document SSH2 in sshd.8 - Bring in b64_ntop and b64_pton from OpenBSD libc (bsd-base64.[ch])
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The client selects the encryption algorithm
to use from those offered by the server.
Additionally, session integrity is provided
through a cryptographic message authentication code
- Remove references to SSLeay. - Big OpenBSD CVS update - markus@cvs.openbsd.org [clientloop.c] - typo [session.c] - update proctitle on pty alloc/dealloc, e.g. w/ windows client [session.c] - update proctitle for proto 1, too [channels.h nchan.c serverloop.c session.c sshd.c] - use c-style comments - deraadt@cvs.openbsd.org [scp.c] - more atomicio - markus@cvs.openbsd.org [channels.c] - set O_NONBLOCK [ssh.1] - update AUTHOR [readconf.c ssh-keygen.c ssh.h] - default DSA key file ~/.ssh/id_dsa [clientloop.c] - typo, rm verbose debug - deraadt@cvs.openbsd.org [ssh-keygen.1] - document DSA use of ssh-keygen [sshd.8] - a start at describing what i understand of the DSA side [ssh-keygen.1] - document -X and -x [ssh-keygen.c] - simplify usage - markus@cvs.openbsd.org [sshd.8] - there is no rhosts_dsa [ssh-keygen.1] - document -y, update -X,-x [nchan.c] - fix close for non-open ssh1 channels [servconf.c servconf.h ssh.h sshd.8 sshd.c ] - s/DsaKey/HostDSAKey/, document option [sshconnect2.c] - respect number_of_password_prompts [channels.c channels.h servconf.c servconf.h session.c sshd.8] - GatewayPorts for sshd, ok deraadt@ [ssh-add.1 ssh-agent.1 ssh.1] - more doc on: DSA, id_dsa, known_hosts2, authorized_keys2 [ssh.1] - more info on proto 2 [sshd.8] - sync AUTHOR w/ ssh.1 [key.c key.h sshconnect.c] - print key type when talking about host keys [packet.c] - clear padding in ssh2 [dsa.c key.c radix.c ssh.h sshconnect1.c uuencode.c uuencode.h] - replace broken uuencode w/ libc b64_ntop [auth2.c] - log failure before sending the reply [key.c radix.c uuencode.c] - remote trailing comments before calling __b64_pton [auth2.c readconf.c readconf.h servconf.c servconf.h ssh.1] [sshconnect2.c sshd.8] - add DSAAuthetication option to ssh/sshd, document SSH2 in sshd.8 - Bring in b64_ntop and b64_pton from OpenBSD libc (bsd-base64.[ch])
2000-05-07 02:03:14 +00:00
(hmac-sha1 or hmac-md5).
.Pp
Protocol version 2 provides a public key based
user (PubkeyAuthentication) or
client host (HostbasedAuthentication) authentication method,
conventional password authentication and challenge response based methods.
- Remove references to SSLeay. - Big OpenBSD CVS update - markus@cvs.openbsd.org [clientloop.c] - typo [session.c] - update proctitle on pty alloc/dealloc, e.g. w/ windows client [session.c] - update proctitle for proto 1, too [channels.h nchan.c serverloop.c session.c sshd.c] - use c-style comments - deraadt@cvs.openbsd.org [scp.c] - more atomicio - markus@cvs.openbsd.org [channels.c] - set O_NONBLOCK [ssh.1] - update AUTHOR [readconf.c ssh-keygen.c ssh.h] - default DSA key file ~/.ssh/id_dsa [clientloop.c] - typo, rm verbose debug - deraadt@cvs.openbsd.org [ssh-keygen.1] - document DSA use of ssh-keygen [sshd.8] - a start at describing what i understand of the DSA side [ssh-keygen.1] - document -X and -x [ssh-keygen.c] - simplify usage - markus@cvs.openbsd.org [sshd.8] - there is no rhosts_dsa [ssh-keygen.1] - document -y, update -X,-x [nchan.c] - fix close for non-open ssh1 channels [servconf.c servconf.h ssh.h sshd.8 sshd.c ] - s/DsaKey/HostDSAKey/, document option [sshconnect2.c] - respect number_of_password_prompts [channels.c channels.h servconf.c servconf.h session.c sshd.8] - GatewayPorts for sshd, ok deraadt@ [ssh-add.1 ssh-agent.1 ssh.1] - more doc on: DSA, id_dsa, known_hosts2, authorized_keys2 [ssh.1] - more info on proto 2 [sshd.8] - sync AUTHOR w/ ssh.1 [key.c key.h sshconnect.c] - print key type when talking about host keys [packet.c] - clear padding in ssh2 [dsa.c key.c radix.c ssh.h sshconnect1.c uuencode.c uuencode.h] - replace broken uuencode w/ libc b64_ntop [auth2.c] - log failure before sending the reply [key.c radix.c uuencode.c] - remote trailing comments before calling __b64_pton [auth2.c readconf.c readconf.h servconf.c servconf.h ssh.1] [sshconnect2.c sshd.8] - add DSAAuthetication option to ssh/sshd, document SSH2 in sshd.8 - Bring in b64_ntop and b64_pton from OpenBSD libc (bsd-base64.[ch])
2000-05-07 02:03:14 +00:00
.Pp
.Ss Command execution and data forwarding
.Pp
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If the client successfully authenticates itself, a dialog for
preparing the session is entered.
At this time the client may request
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things like allocating a pseudo-tty, forwarding X11 connections,
forwarding TCP/IP connections, or forwarding the authentication agent
connection over the secure channel.
.Pp
Finally, the client either requests a shell or execution of a command.
The sides then enter session mode.
In this mode, either side may send
1999-10-28 23:15:49 +00:00
data at any time, and such data is forwarded to/from the shell or
command on the server side, and the user terminal in the client side.
.Pp
When the user program terminates and all forwarded X11 and other
connections have been closed, the server sends command exit status to
the client, and both sides exit.
.Pp
.Nm
can be configured using command-line options or a configuration
file.
Command-line options override values specified in the
1999-10-28 23:15:49 +00:00
configuration file.
.Pp
.Nm
rereads its configuration file when it receives a hangup signal,
.Dv SIGHUP ,
by executing itself with the name it was started as, i.e.,
.Pa /usr/sbin/sshd .
.Pp
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The options are as follows:
.Bl -tag -width Ds
.It Fl b Ar bits
Specifies the number of bits in the ephemeral protocol version 1
server key (default 768).
1999-10-28 23:15:49 +00:00
.It Fl d
Debug mode.
The server sends verbose debug output to the system
log, and does not put itself in the background.
The server also will not fork and will only process one connection.
This option is only intended for debugging for the server.
Multiple -d options increase the debugging level.
- (djm) Big OpenBSD sync: - markus@cvs.openbsd.org 2000/09/30 10:27:44 [log.c] allow loglevel debug - markus@cvs.openbsd.org 2000/10/03 11:59:57 [packet.c] hmac->mac - markus@cvs.openbsd.org 2000/10/03 12:03:03 [auth-krb4.c auth-passwd.c auth-rh-rsa.c auth-rhosts.c auth-rsa.c auth1.c] move fake-auth from auth1.c to individual auth methods, disables s/key in debug-msg - markus@cvs.openbsd.org 2000/10/03 12:16:48 ssh.c do not resolve canonname, i have no idea why this was added oin ossh - markus@cvs.openbsd.org 2000/10/09 15:30:44 ssh-keygen.1 ssh-keygen.c -X now reads private ssh.com DSA keys, too. - markus@cvs.openbsd.org 2000/10/09 15:32:34 auth-options.c clear options on every call. - markus@cvs.openbsd.org 2000/10/09 15:51:00 authfd.c authfd.h interop with ssh-agent2, from <res@shore.net> - markus@cvs.openbsd.org 2000/10/10 14:20:45 compat.c use rexexp for version string matching - provos@cvs.openbsd.org 2000/10/10 22:02:18 [kex.c kex.h myproposal.h ssh.h ssh2.h sshconnect2.c sshd.c dh.c dh.h] First rough implementation of the diffie-hellman group exchange. The client can ask the server for bigger groups to perform the diffie-hellman in, thus increasing the attack complexity when using ciphers with longer keys. University of Windsor provided network, T the company. - markus@cvs.openbsd.org 2000/10/11 13:59:52 [auth-rsa.c auth2.c] clear auth options unless auth sucessfull - markus@cvs.openbsd.org 2000/10/11 14:00:27 [auth-options.h] clear auth options unless auth sucessfull - markus@cvs.openbsd.org 2000/10/11 14:03:27 [scp.1 scp.c] support 'scp -o' with help from mouring@pconline.com - markus@cvs.openbsd.org 2000/10/11 14:11:35 [dh.c] Wall - markus@cvs.openbsd.org 2000/10/11 14:14:40 [auth.h auth2.c readconf.c readconf.h readpass.c servconf.c servconf.h] [ssh.h sshconnect2.c sshd_config auth2-skey.c cli.c cli.h] add support for s/key (kbd-interactive) to ssh2, based on work by mkiernan@avantgo.com and me - markus@cvs.openbsd.org 2000/10/11 14:27:24 [auth.c auth1.c auth2.c authfile.c cipher.c cipher.h kex.c kex.h] [myproposal.h packet.c readconf.c session.c ssh.c ssh.h sshconnect1.c] [sshconnect2.c sshd.c] new cipher framework - markus@cvs.openbsd.org 2000/10/11 14:45:21 [cipher.c] remove DES - markus@cvs.openbsd.org 2000/10/12 03:59:20 [cipher.c cipher.h sshconnect1.c sshconnect2.c sshd.c] enable DES in SSH-1 clients only - markus@cvs.openbsd.org 2000/10/12 08:21:13 [kex.h packet.c] remove unused - markus@cvs.openbsd.org 2000/10/13 12:34:46 [sshd.c] Kludge for F-Secure Macintosh < 1.0.2; appro@fy.chalmers.se - markus@cvs.openbsd.org 2000/10/13 12:59:15 [cipher.c cipher.h myproposal.h rijndael.c rijndael.h] rijndael/aes support - markus@cvs.openbsd.org 2000/10/13 13:10:54 [sshd.8] more info about -V - markus@cvs.openbsd.org 2000/10/13 13:12:02 [myproposal.h] prefer no compression
2000-10-14 05:23:11 +00:00
Maximum is 3.
.It Fl e
When this option is specified,
.Nm
will send the output to the standard error instead of the system log.
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.It Fl f Ar configuration_file
Specifies the name of the configuration file.
The default is
.Pa /etc/sshd_config .
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.Nm
refuses to start if there is no configuration file.
.It Fl g Ar login_grace_time
Gives the grace time for clients to authenticate themselves (default
2001-01-07 11:53:40 +00:00
600 seconds).
If the client fails to authenticate the user within
this many seconds, the server disconnects and exits.
A value of zero indicates no limit.
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.It Fl h Ar host_key_file
Specifies the file from which the host key is read (default
.Pa /etc/ssh_host_key ) .
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This option must be given if
.Nm
is not run as root (as the normal
host file is normally not readable by anyone but root).
It is possible to have multiple host key files for
the different protocol versions and host key algorithms.
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.It Fl i
Specifies that
.Nm
is being run from inetd.
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.Nm
is normally not run
from inetd because it needs to generate the server key before it can
respond to the client, and this may take tens of seconds.
Clients would have to wait too long if the key was regenerated every time.
However, with small key sizes (e.g., 512) using
1999-10-28 23:15:49 +00:00
.Nm
from inetd may
be feasible.
.It Fl k Ar key_gen_time
Specifies how often the ephemeral protocol version 1 server key is
regenerated (default 3600 seconds, or one hour).
The motivation for regenerating the key fairly
1999-10-28 23:15:49 +00:00
often is that the key is not stored anywhere, and after about an hour,
it becomes impossible to recover the key for decrypting intercepted
communications even if the machine is cracked into or physically
seized.
A value of zero indicates that the key will never be regenerated.
.It Fl o Ar option
Can be used to give options in the format used in the configuration file.
This is useful for specifying options for which there is no separate
command-line flag.
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.It Fl p Ar port
Specifies the port on which the server listens for connections
(default 22).
.It Fl q
Quiet mode.
Nothing is sent to the system log.
Normally the beginning,
1999-10-28 23:15:49 +00:00
authentication, and termination of each connection is logged.
.It Fl t
Test mode.
Only check the validity of the configuration file and sanity of the keys.
This is useful for updating
.Nm
reliably as configuration options may change.
.It Fl u Ar len
This option is used to specify the size of the field
in the
.Li utmp
structure that holds the remote host name.
If the resolved host name is longer than
.Ar len ,
the dotted decimal value will be used instead.
This allows hosts with very long host names that
overflow this field to still be uniquely identified.
Specifying
.Fl u0
indicates that only dotted decimal addresses
should be put into the
.Pa utmp
file.
.Fl u0
is also be used to prevent
.Nm
from making DNS requests unless the authentication
mechanism or configuration requires it.
Authentication mechanisms that may require DNS include
.Cm RhostsAuthentication ,
.Cm RhostsRSAAuthentication ,
.Cm HostbasedAuthentication
and using a
.Cm from="pattern-list"
option in a key file.
.It Fl D
When this option is specified
.Nm
will not detach and does not become a daemon.
This allows easy monitoring of
.Nm sshd .
.It Fl 4
Forces
.Nm
to use IPv4 addresses only.
.It Fl 6
Forces
.Nm
to use IPv6 addresses only.
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.El
.Sh CONFIGURATION FILE
.Nm
reads configuration data from
.Pa /etc/sshd_config
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(or the file specified with
.Fl f
on the command line).
The file contains keyword-argument pairs, one per line.
Lines starting with
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.Ql #
and empty lines are interpreted as comments.
.Pp
The possible
keywords and their meanings are as follows (note that
keywords are case-insensitive and arguments are case-sensitive):
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.Bl -tag -width Ds
.It Cm AFSTokenPassing
Specifies whether an AFS token may be forwarded to the server.
Default is
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.Dq yes .
.It Cm AllowGroups
2001-02-10 22:19:23 +00:00
This keyword can be followed by a list of group names, separated
by spaces.
If specified, login is allowed only for users whose primary
group or supplementary group list matches one of the patterns.
1999-10-28 23:15:49 +00:00
.Ql \&*
and
.Ql ?
can be used as
wildcards in the patterns.
Only group names are valid; a numerical group ID is not recognized.
By default login is allowed regardless of the group list.
1999-10-28 23:15:49 +00:00
.Pp
.It Cm AllowTcpForwarding
Specifies whether TCP forwarding is permitted.
The default is
.Dq yes .
Note that disabling TCP forwarding does not improve security unless
users are also denied shell access, as they can always install their
own forwarders.
.Pp
1999-10-28 23:15:49 +00:00
.It Cm AllowUsers
2001-02-10 22:19:23 +00:00
This keyword can be followed by a list of user names, separated
by spaces.
If specified, login is allowed only for users names that
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match one of the patterns.
.Ql \&*
and
.Ql ?
can be used as
wildcards in the patterns.
Only user names are valid; a numerical user ID is not recognized.
By default login is allowed regardless of the user name.
If the pattern takes the form USER@HOST then USER and HOST
are separately checked, restricting logins to particular
users from particular hosts.
1999-10-28 23:15:49 +00:00
.Pp
.It Cm AuthorizedKeysFile
Specifies the file that contains the public keys that can be used
for user authentication.
.Cm AuthorizedKeysFile
may contain tokens of the form %T which are substituted during connection
set-up. The following tokens are defined: %% is replaced by a literal '%',
%h is replaced by the home directory of the user being authenticated and
%u is replaced by the username of that user.
After expansion,
.Cm AuthorizedKeysFile
is taken to be an absolute path or one relative to the user's home
directory.
The default is
.Dq .ssh/authorized_keys
.It Cm Banner
In some jurisdictions, sending a warning message before authentication
may be relevant for getting legal protection.
The contents of the specified file are sent to the remote user before
authentication is allowed.
This option is only available for protocol version 2.
.Pp
.It Cm ChallengeResponseAuthentication
Specifies whether challenge response authentication is allowed.
All authentication styles from
.Xr login.conf 5
are supported.
The default is
.Dq yes .
.It Cm Ciphers
Specifies the ciphers allowed for protocol version 2.
Multiple ciphers must be comma-separated.
The default is
.Dq aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour.
.It Cm ClientAliveInterval
Sets a timeout interval in seconds after which if no data has been received
from the client,
.Nm
will send a message through the encrypted
channel to request a response from the client.
The default
is 0, indicating that these messages will not be sent to the client.
This option applies to protocol version 2 only.
.It Cm ClientAliveCountMax
Sets the number of client alive messages (see above) which may be
sent without
.Nm
receiving any messages back from the client. If this threshold is
reached while client alive messages are being sent,
.Nm
will disconnect the client, terminating the session. It is important
to note that the use of client alive messages is very different from
.Cm KeepAlive
(below). The client alive messages are sent through the
encrypted channel and therefore will not be spoofable. The TCP keepalive
option enabled by
.Cm KeepAlive
is spoofable. The client alive mechanism is valuable when the client or
server depend on knowing when a connection has become inactive.
.Pp
The default value is 3. If
.Cm ClientAliveInterval
(above) is set to 15, and
.Cm ClientAliveCountMax
is left at the default, unresponsive ssh clients
will be disconnected after approximately 45 seconds.
1999-10-28 23:15:49 +00:00
.It Cm DenyGroups
This keyword can be followed by a number of group names, separated
by spaces.
Users whose primary group or supplementary group list matches
one of the patterns aren't allowed to log in.
1999-10-28 23:15:49 +00:00
.Ql \&*
and
.Ql ?
can be used as
wildcards in the patterns.
Only group names are valid; a numerical group ID is not recognized.
By default login is allowed regardless of the group list.
1999-10-28 23:15:49 +00:00
.Pp
.It Cm DenyUsers
This keyword can be followed by a number of user names, separated
by spaces.
Login is disallowed for user names that match one of the patterns.
1999-10-28 23:15:49 +00:00
.Ql \&*
and
.Ql ?
can be used as wildcards in the patterns.
Only user names are valid; a numerical user ID is not recognized.
By default login is allowed regardless of the user name.
- Remove references to SSLeay. - Big OpenBSD CVS update - markus@cvs.openbsd.org [clientloop.c] - typo [session.c] - update proctitle on pty alloc/dealloc, e.g. w/ windows client [session.c] - update proctitle for proto 1, too [channels.h nchan.c serverloop.c session.c sshd.c] - use c-style comments - deraadt@cvs.openbsd.org [scp.c] - more atomicio - markus@cvs.openbsd.org [channels.c] - set O_NONBLOCK [ssh.1] - update AUTHOR [readconf.c ssh-keygen.c ssh.h] - default DSA key file ~/.ssh/id_dsa [clientloop.c] - typo, rm verbose debug - deraadt@cvs.openbsd.org [ssh-keygen.1] - document DSA use of ssh-keygen [sshd.8] - a start at describing what i understand of the DSA side [ssh-keygen.1] - document -X and -x [ssh-keygen.c] - simplify usage - markus@cvs.openbsd.org [sshd.8] - there is no rhosts_dsa [ssh-keygen.1] - document -y, update -X,-x [nchan.c] - fix close for non-open ssh1 channels [servconf.c servconf.h ssh.h sshd.8 sshd.c ] - s/DsaKey/HostDSAKey/, document option [sshconnect2.c] - respect number_of_password_prompts [channels.c channels.h servconf.c servconf.h session.c sshd.8] - GatewayPorts for sshd, ok deraadt@ [ssh-add.1 ssh-agent.1 ssh.1] - more doc on: DSA, id_dsa, known_hosts2, authorized_keys2 [ssh.1] - more info on proto 2 [sshd.8] - sync AUTHOR w/ ssh.1 [key.c key.h sshconnect.c] - print key type when talking about host keys [packet.c] - clear padding in ssh2 [dsa.c key.c radix.c ssh.h sshconnect1.c uuencode.c uuencode.h] - replace broken uuencode w/ libc b64_ntop [auth2.c] - log failure before sending the reply [key.c radix.c uuencode.c] - remote trailing comments before calling __b64_pton [auth2.c readconf.c readconf.h servconf.c servconf.h ssh.1] [sshconnect2.c sshd.8] - add DSAAuthetication option to ssh/sshd, document SSH2 in sshd.8 - Bring in b64_ntop and b64_pton from OpenBSD libc (bsd-base64.[ch])
2000-05-07 02:03:14 +00:00
.It Cm GatewayPorts
Specifies whether remote hosts are allowed to connect to ports
forwarded for the client.
By default,
.Nm
binds remote port forwardings to the loopback addresss. This
prevents other remote hosts from connecting to forwarded ports.
.Cm GatewayPorts
can be used to specify that
.Nm
should bind remote port forwardings to the wildcard address,
thus allowing remote hosts to connect to forwarded ports.
- Remove references to SSLeay. - Big OpenBSD CVS update - markus@cvs.openbsd.org [clientloop.c] - typo [session.c] - update proctitle on pty alloc/dealloc, e.g. w/ windows client [session.c] - update proctitle for proto 1, too [channels.h nchan.c serverloop.c session.c sshd.c] - use c-style comments - deraadt@cvs.openbsd.org [scp.c] - more atomicio - markus@cvs.openbsd.org [channels.c] - set O_NONBLOCK [ssh.1] - update AUTHOR [readconf.c ssh-keygen.c ssh.h] - default DSA key file ~/.ssh/id_dsa [clientloop.c] - typo, rm verbose debug - deraadt@cvs.openbsd.org [ssh-keygen.1] - document DSA use of ssh-keygen [sshd.8] - a start at describing what i understand of the DSA side [ssh-keygen.1] - document -X and -x [ssh-keygen.c] - simplify usage - markus@cvs.openbsd.org [sshd.8] - there is no rhosts_dsa [ssh-keygen.1] - document -y, update -X,-x [nchan.c] - fix close for non-open ssh1 channels [servconf.c servconf.h ssh.h sshd.8 sshd.c ] - s/DsaKey/HostDSAKey/, document option [sshconnect2.c] - respect number_of_password_prompts [channels.c channels.h servconf.c servconf.h session.c sshd.8] - GatewayPorts for sshd, ok deraadt@ [ssh-add.1 ssh-agent.1 ssh.1] - more doc on: DSA, id_dsa, known_hosts2, authorized_keys2 [ssh.1] - more info on proto 2 [sshd.8] - sync AUTHOR w/ ssh.1 [key.c key.h sshconnect.c] - print key type when talking about host keys [packet.c] - clear padding in ssh2 [dsa.c key.c radix.c ssh.h sshconnect1.c uuencode.c uuencode.h] - replace broken uuencode w/ libc b64_ntop [auth2.c] - log failure before sending the reply [key.c radix.c uuencode.c] - remote trailing comments before calling __b64_pton [auth2.c readconf.c readconf.h servconf.c servconf.h ssh.1] [sshconnect2.c sshd.8] - add DSAAuthetication option to ssh/sshd, document SSH2 in sshd.8 - Bring in b64_ntop and b64_pton from OpenBSD libc (bsd-base64.[ch])
2000-05-07 02:03:14 +00:00
The argument must be
.Dq yes
or
.Dq no .
The default is
.Dq no .
.It Cm HostbasedAuthentication
Specifies whether rhosts or /etc/hosts.equiv authentication together
with successful public key client host authentication is allowed
(hostbased authentication).
This option is similar to
.Cm RhostsRSAAuthentication
and applies to protocol version 2 only.
The default is
.Dq no .
1999-10-28 23:15:49 +00:00
.It Cm HostKey
- (djm) Merge OpenBSD changes: - markus@cvs.openbsd.org 2000/11/06 16:04:56 [channels.c channels.h clientloop.c nchan.c serverloop.c] [session.c ssh.c] agent forwarding and -R for ssh2, based on work from jhuuskon@messi.uku.fi - markus@cvs.openbsd.org 2000/11/06 16:13:27 [ssh.c sshconnect.c sshd.c] do not disabled rhosts(rsa) if server port > 1024; from pekkas@netcore.fi - markus@cvs.openbsd.org 2000/11/06 16:16:35 [sshconnect.c] downgrade client to 1.3 if server is 1.4; help from mdb@juniper.net - markus@cvs.openbsd.org 2000/11/09 18:04:40 [auth1.c] typo; from mouring@pconline.com - markus@cvs.openbsd.org 2000/11/12 12:03:28 [ssh-agent.c] off-by-one when removing a key from the agent - markus@cvs.openbsd.org 2000/11/12 12:50:39 [auth-rh-rsa.c auth2.c authfd.c authfd.h] [authfile.c hostfile.c kex.c kex.h key.c key.h myproposal.h] [readconf.c readconf.h rsa.c rsa.h servconf.c servconf.h ssh-add.c] [ssh-agent.c ssh-keygen.1 ssh-keygen.c ssh.1 ssh.c ssh_config] [sshconnect1.c sshconnect2.c sshd.8 sshd.c sshd_config ssh-dss.c] [ssh-dss.h ssh-rsa.c ssh-rsa.h dsa.c dsa.h] add support for RSA to SSH2. please test. there are now 3 types of keys: RSA1 is used by ssh-1 only, RSA and DSA are used by SSH2. you can use 'ssh-keygen -t rsa -f ssh2_rsa_file' to generate RSA keys for SSH2 and use the RSA keys for hostkeys or for user keys. SSH2 RSA or DSA keys are added to .ssh/authorised_keys2 as before. - (djm) Fix up Makefile and Redhat init script to create RSA host keys - (djm) Change to interim version
2000-11-13 11:57:25 +00:00
Specifies the file containing the private host keys (default
- Remove references to SSLeay. - Big OpenBSD CVS update - markus@cvs.openbsd.org [clientloop.c] - typo [session.c] - update proctitle on pty alloc/dealloc, e.g. w/ windows client [session.c] - update proctitle for proto 1, too [channels.h nchan.c serverloop.c session.c sshd.c] - use c-style comments - deraadt@cvs.openbsd.org [scp.c] - more atomicio - markus@cvs.openbsd.org [channels.c] - set O_NONBLOCK [ssh.1] - update AUTHOR [readconf.c ssh-keygen.c ssh.h] - default DSA key file ~/.ssh/id_dsa [clientloop.c] - typo, rm verbose debug - deraadt@cvs.openbsd.org [ssh-keygen.1] - document DSA use of ssh-keygen [sshd.8] - a start at describing what i understand of the DSA side [ssh-keygen.1] - document -X and -x [ssh-keygen.c] - simplify usage - markus@cvs.openbsd.org [sshd.8] - there is no rhosts_dsa [ssh-keygen.1] - document -y, update -X,-x [nchan.c] - fix close for non-open ssh1 channels [servconf.c servconf.h ssh.h sshd.8 sshd.c ] - s/DsaKey/HostDSAKey/, document option [sshconnect2.c] - respect number_of_password_prompts [channels.c channels.h servconf.c servconf.h session.c sshd.8] - GatewayPorts for sshd, ok deraadt@ [ssh-add.1 ssh-agent.1 ssh.1] - more doc on: DSA, id_dsa, known_hosts2, authorized_keys2 [ssh.1] - more info on proto 2 [sshd.8] - sync AUTHOR w/ ssh.1 [key.c key.h sshconnect.c] - print key type when talking about host keys [packet.c] - clear padding in ssh2 [dsa.c key.c radix.c ssh.h sshconnect1.c uuencode.c uuencode.h] - replace broken uuencode w/ libc b64_ntop [auth2.c] - log failure before sending the reply [key.c radix.c uuencode.c] - remote trailing comments before calling __b64_pton [auth2.c readconf.c readconf.h servconf.c servconf.h ssh.1] [sshconnect2.c sshd.8] - add DSAAuthetication option to ssh/sshd, document SSH2 in sshd.8 - Bring in b64_ntop and b64_pton from OpenBSD libc (bsd-base64.[ch])
2000-05-07 02:03:14 +00:00
.Pa /etc/ssh_host_key )
- (djm) Merge OpenBSD changes: - markus@cvs.openbsd.org 2000/11/06 16:04:56 [channels.c channels.h clientloop.c nchan.c serverloop.c] [session.c ssh.c] agent forwarding and -R for ssh2, based on work from jhuuskon@messi.uku.fi - markus@cvs.openbsd.org 2000/11/06 16:13:27 [ssh.c sshconnect.c sshd.c] do not disabled rhosts(rsa) if server port > 1024; from pekkas@netcore.fi - markus@cvs.openbsd.org 2000/11/06 16:16:35 [sshconnect.c] downgrade client to 1.3 if server is 1.4; help from mdb@juniper.net - markus@cvs.openbsd.org 2000/11/09 18:04:40 [auth1.c] typo; from mouring@pconline.com - markus@cvs.openbsd.org 2000/11/12 12:03:28 [ssh-agent.c] off-by-one when removing a key from the agent - markus@cvs.openbsd.org 2000/11/12 12:50:39 [auth-rh-rsa.c auth2.c authfd.c authfd.h] [authfile.c hostfile.c kex.c kex.h key.c key.h myproposal.h] [readconf.c readconf.h rsa.c rsa.h servconf.c servconf.h ssh-add.c] [ssh-agent.c ssh-keygen.1 ssh-keygen.c ssh.1 ssh.c ssh_config] [sshconnect1.c sshconnect2.c sshd.8 sshd.c sshd_config ssh-dss.c] [ssh-dss.h ssh-rsa.c ssh-rsa.h dsa.c dsa.h] add support for RSA to SSH2. please test. there are now 3 types of keys: RSA1 is used by ssh-1 only, RSA and DSA are used by SSH2. you can use 'ssh-keygen -t rsa -f ssh2_rsa_file' to generate RSA keys for SSH2 and use the RSA keys for hostkeys or for user keys. SSH2 RSA or DSA keys are added to .ssh/authorised_keys2 as before. - (djm) Fix up Makefile and Redhat init script to create RSA host keys - (djm) Change to interim version
2000-11-13 11:57:25 +00:00
used by SSH protocol versions 1 and 2.
1999-10-28 23:15:49 +00:00
Note that
.Nm
Hopefully things did not get mixed around too much. It compiles under Linux and works. So that is at least a good sign. =) 20010122 - (bal) OpenBSD Resync - markus@cvs.openbsd.org 2001/01/19 12:45:26 GMT 2001 by markus [servconf.c ssh.h sshd.c] only auth-chall.c needs #ifdef SKEY - markus@cvs.openbsd.org 2001/01/19 15:55:10 GMT 2001 by markus [auth-krb4.c auth-options.c auth-rh-rsa.c auth-rhosts.c auth-rsa.c auth1.c auth2.c channels.c clientloop.c dh.c dispatch.c nchan.c packet.c pathname.h readconf.c scp.c servconf.c serverloop.c session.c ssh-add.c ssh-keygen.c ssh-keyscan.c ssh.c ssh.h ssh1.h sshconnect1.c sshd.c ttymodes.c] move ssh1 definitions to ssh1.h, pathnames to pathnames.h - markus@cvs.openbsd.org 2001/01/19 16:48:14 [sshd.8] fix typo; from stevesk@ - markus@cvs.openbsd.org 2001/01/19 16:50:58 [ssh-dss.c] clear and free digest, make consistent with other code (use dlen); from stevesk@ - markus@cvs.openbsd.org 2001/01/20 15:55:20 GMT 2001 by markus [auth-options.c auth-options.h auth-rsa.c auth2.c] pass the filename to auth_parse_options() - markus@cvs.openbsd.org 2001/01/20 17:59:40 GMT 2001 [readconf.c] fix SIGSEGV from -o ""; problem noted by jehsom@togetherweb.com - stevesk@cvs.openbsd.org 2001/01/20 18:20:29 [sshconnect2.c] dh_new_group() does not return NULL. ok markus@ - markus@cvs.openbsd.org 2001/01/20 21:33:42 [ssh-add.c] do not loop forever if askpass does not exist; from andrew@pimlott.ne.mediaone.net - djm@cvs.openbsd.org 2001/01/20 23:00:56 [servconf.c] Check for NULL return from strdelim; ok markus - djm@cvs.openbsd.org 2001/01/20 23:02:07 [readconf.c] KNF; ok markus - jakob@cvs.openbsd.org 2001/01/21 9:00:33 [ssh-keygen.1] remove -R flag; ok markus@ - markus@cvs.openbsd.org 2001/01/21 19:05:40 [atomicio.c automicio.h auth-chall.c auth-krb4.c auth-options.c auth-options.h auth-passwd.c auth-rh-rsa.c auth-rhosts.c auth-rsa.c auth.c auth.h auth1.c auth2-chall.c auth2.c authfd.c authfile.c bufaux.c bufaux.h buffer.c canahost.c canahost.h channels.c cipher.c cli.c clientloop.c clientloop.h compat.c compress.c deattack.c dh.c dispatch.c groupaccess.c hmac.c hostfile.c kex.c key.c key.h log-client.c log-server.c log.c log.h login.c login.h match.c misc.c misc.h nchan.c packet.c pty.c radix.h readconf.c readpass.c readpass.h rsa.c scp.c servconf.c serverloop.c serverloop.h session.c sftp-server.c ssh-add.c ssh-agent.c ssh-dss.c ssh-keygen.c ssh-keyscan.c ssh-rsa.c ssh.c ssh.h sshconnect.c sshconnect.h sshconnect1.c sshconnect2.c sshd.c tildexpand.c tildexpand.h ttysmodes.c uidswap.c xmalloc.c] split ssh.h and try to cleanup the #include mess. remove unnecessary #includes. rename util.[ch] -> misc.[ch] - (bal) renamed 'PIDDIR' to '_PATH_SSH_PIDDIR' to match OpenBSD tree - (bal) Moved #ifdef KRB4 in auth-krb4.c above the #include to resolve conflict when compiling for non-kerb install - (bal) removed the #ifdef SKEY in auth1.c to match Markus' changes on 1/19.
2001-01-22 05:34:40 +00:00
will refuse to use a file if it is group/world-accessible.
- (djm) Merge OpenBSD changes: - markus@cvs.openbsd.org 2000/11/06 16:04:56 [channels.c channels.h clientloop.c nchan.c serverloop.c] [session.c ssh.c] agent forwarding and -R for ssh2, based on work from jhuuskon@messi.uku.fi - markus@cvs.openbsd.org 2000/11/06 16:13:27 [ssh.c sshconnect.c sshd.c] do not disabled rhosts(rsa) if server port > 1024; from pekkas@netcore.fi - markus@cvs.openbsd.org 2000/11/06 16:16:35 [sshconnect.c] downgrade client to 1.3 if server is 1.4; help from mdb@juniper.net - markus@cvs.openbsd.org 2000/11/09 18:04:40 [auth1.c] typo; from mouring@pconline.com - markus@cvs.openbsd.org 2000/11/12 12:03:28 [ssh-agent.c] off-by-one when removing a key from the agent - markus@cvs.openbsd.org 2000/11/12 12:50:39 [auth-rh-rsa.c auth2.c authfd.c authfd.h] [authfile.c hostfile.c kex.c kex.h key.c key.h myproposal.h] [readconf.c readconf.h rsa.c rsa.h servconf.c servconf.h ssh-add.c] [ssh-agent.c ssh-keygen.1 ssh-keygen.c ssh.1 ssh.c ssh_config] [sshconnect1.c sshconnect2.c sshd.8 sshd.c sshd_config ssh-dss.c] [ssh-dss.h ssh-rsa.c ssh-rsa.h dsa.c dsa.h] add support for RSA to SSH2. please test. there are now 3 types of keys: RSA1 is used by ssh-1 only, RSA and DSA are used by SSH2. you can use 'ssh-keygen -t rsa -f ssh2_rsa_file' to generate RSA keys for SSH2 and use the RSA keys for hostkeys or for user keys. SSH2 RSA or DSA keys are added to .ssh/authorised_keys2 as before. - (djm) Fix up Makefile and Redhat init script to create RSA host keys - (djm) Change to interim version
2000-11-13 11:57:25 +00:00
It is possible to have multiple host key files.
.Dq rsa1
keys are used for version 1 and
.Dq dsa
or
.Dq rsa
are used for version 2 of the SSH protocol.
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.It Cm IgnoreRhosts
- OpenBSD CVS updates to v1.2.3 [ssh.h atomicio.c] - int atomicio -> ssize_t (for alpha). ok deraadt@ [auth-rsa.c] - delay MD5 computation until client sends response, free() early, cleanup. [cipher.c] - void* -> unsigned char*, ok niels@ [hostfile.c] - remove unused variable 'len'. fix comments. - remove unused variable [log-client.c log-server.c] - rename a cpp symbol, to avoid param.h collision [packet.c] - missing xfree() - getsockname() requires initialized tolen; andy@guildsoftware.com - use getpeername() in packet_connection_is_on_socket(), fixes sshd -i; from Holger.Trapp@Informatik.TU-Chemnitz.DE [pty.c pty.h] - register cleanup for pty earlier. move code for pty-owner handling to pty.c ok provos@, dugsong@ [readconf.c] - turn off x11-fwd for the client, too. [rsa.c] - PKCS#1 padding [scp.c] - allow '.' in usernames; from jedgar@fxp.org [servconf.c] - typo: ignore_user_known_hosts int->flag; naddy@mips.rhein-neckar.de - sync with sshd_config [ssh-keygen.c] - enable ssh-keygen -l -f ~/.ssh/known_hosts, ok deraadt@ [ssh.1] - Change invalid 'CHAT' loglevel to 'VERBOSE' [ssh.c] - suppress AAAA query host when '-4' is used; from shin@nd.net.fujitsu.co.jp - turn off x11-fwd for the client, too. [sshconnect.c] - missing xfree() - retry rresvport_af(), too. from sumikawa@ebina.hitachi.co.jp. - read error vs. "Connection closed by remote host" [sshd.8] - ie. -> i.e., - do not link to a commercial page.. - sync with sshd_config [sshd.c] - no need for poll.h; from bright@wintelcom.net - log with level log() not fatal() if peer behaves badly. - don't panic if client behaves strange. ok deraadt@ - make no-port-forwarding for RSA keys deny both -L and -R style fwding - delay close() of pty until the pty has been chowned back to root - oops, fix comment, too. - missing xfree() - move XAUTHORITY to subdir. ok dugsong@. fixes debian bug #57907, too. (http://cgi.debian.org/cgi-bin/bugreport.cgi?archive=no&bug=57907) - register cleanup for pty earlier. move code for pty-owner handling to pty.c ok provos@, dugsong@ - create x11 cookie file - fix pr 1113, fclose() -> pclose(), todo: remote popen() - version 1.2.3 - Cleaned up
2000-03-09 10:27:49 +00:00
Specifies that
.Pa .rhosts
and
- OpenBSD CVS updates to v1.2.3 [ssh.h atomicio.c] - int atomicio -> ssize_t (for alpha). ok deraadt@ [auth-rsa.c] - delay MD5 computation until client sends response, free() early, cleanup. [cipher.c] - void* -> unsigned char*, ok niels@ [hostfile.c] - remove unused variable 'len'. fix comments. - remove unused variable [log-client.c log-server.c] - rename a cpp symbol, to avoid param.h collision [packet.c] - missing xfree() - getsockname() requires initialized tolen; andy@guildsoftware.com - use getpeername() in packet_connection_is_on_socket(), fixes sshd -i; from Holger.Trapp@Informatik.TU-Chemnitz.DE [pty.c pty.h] - register cleanup for pty earlier. move code for pty-owner handling to pty.c ok provos@, dugsong@ [readconf.c] - turn off x11-fwd for the client, too. [rsa.c] - PKCS#1 padding [scp.c] - allow '.' in usernames; from jedgar@fxp.org [servconf.c] - typo: ignore_user_known_hosts int->flag; naddy@mips.rhein-neckar.de - sync with sshd_config [ssh-keygen.c] - enable ssh-keygen -l -f ~/.ssh/known_hosts, ok deraadt@ [ssh.1] - Change invalid 'CHAT' loglevel to 'VERBOSE' [ssh.c] - suppress AAAA query host when '-4' is used; from shin@nd.net.fujitsu.co.jp - turn off x11-fwd for the client, too. [sshconnect.c] - missing xfree() - retry rresvport_af(), too. from sumikawa@ebina.hitachi.co.jp. - read error vs. "Connection closed by remote host" [sshd.8] - ie. -> i.e., - do not link to a commercial page.. - sync with sshd_config [sshd.c] - no need for poll.h; from bright@wintelcom.net - log with level log() not fatal() if peer behaves badly. - don't panic if client behaves strange. ok deraadt@ - make no-port-forwarding for RSA keys deny both -L and -R style fwding - delay close() of pty until the pty has been chowned back to root - oops, fix comment, too. - missing xfree() - move XAUTHORITY to subdir. ok dugsong@. fixes debian bug #57907, too. (http://cgi.debian.org/cgi-bin/bugreport.cgi?archive=no&bug=57907) - register cleanup for pty earlier. move code for pty-owner handling to pty.c ok provos@, dugsong@ - create x11 cookie file - fix pr 1113, fclose() -> pclose(), todo: remote popen() - version 1.2.3 - Cleaned up
2000-03-09 10:27:49 +00:00
.Pa .shosts
files will not be used in
.Cm RhostsAuthentication ,
.Cm RhostsRSAAuthentication
or
.Cm HostbasedAuthentication .
.Pp
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.Pa /etc/hosts.equiv
and
.Pa /etc/shosts.equiv
are still used.
The default is
- OpenBSD CVS updates to v1.2.3 [ssh.h atomicio.c] - int atomicio -> ssize_t (for alpha). ok deraadt@ [auth-rsa.c] - delay MD5 computation until client sends response, free() early, cleanup. [cipher.c] - void* -> unsigned char*, ok niels@ [hostfile.c] - remove unused variable 'len'. fix comments. - remove unused variable [log-client.c log-server.c] - rename a cpp symbol, to avoid param.h collision [packet.c] - missing xfree() - getsockname() requires initialized tolen; andy@guildsoftware.com - use getpeername() in packet_connection_is_on_socket(), fixes sshd -i; from Holger.Trapp@Informatik.TU-Chemnitz.DE [pty.c pty.h] - register cleanup for pty earlier. move code for pty-owner handling to pty.c ok provos@, dugsong@ [readconf.c] - turn off x11-fwd for the client, too. [rsa.c] - PKCS#1 padding [scp.c] - allow '.' in usernames; from jedgar@fxp.org [servconf.c] - typo: ignore_user_known_hosts int->flag; naddy@mips.rhein-neckar.de - sync with sshd_config [ssh-keygen.c] - enable ssh-keygen -l -f ~/.ssh/known_hosts, ok deraadt@ [ssh.1] - Change invalid 'CHAT' loglevel to 'VERBOSE' [ssh.c] - suppress AAAA query host when '-4' is used; from shin@nd.net.fujitsu.co.jp - turn off x11-fwd for the client, too. [sshconnect.c] - missing xfree() - retry rresvport_af(), too. from sumikawa@ebina.hitachi.co.jp. - read error vs. "Connection closed by remote host" [sshd.8] - ie. -> i.e., - do not link to a commercial page.. - sync with sshd_config [sshd.c] - no need for poll.h; from bright@wintelcom.net - log with level log() not fatal() if peer behaves badly. - don't panic if client behaves strange. ok deraadt@ - make no-port-forwarding for RSA keys deny both -L and -R style fwding - delay close() of pty until the pty has been chowned back to root - oops, fix comment, too. - missing xfree() - move XAUTHORITY to subdir. ok dugsong@. fixes debian bug #57907, too. (http://cgi.debian.org/cgi-bin/bugreport.cgi?archive=no&bug=57907) - register cleanup for pty earlier. move code for pty-owner handling to pty.c ok provos@, dugsong@ - create x11 cookie file - fix pr 1113, fclose() -> pclose(), todo: remote popen() - version 1.2.3 - Cleaned up
2000-03-09 10:27:49 +00:00
.Dq yes .
.It Cm IgnoreUserKnownHosts
Specifies whether
.Nm
should ignore the user's
.Pa $HOME/.ssh/known_hosts
during
.Cm RhostsRSAAuthentication
or
.Cm HostbasedAuthentication .
The default is
.Dq no .
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.It Cm KeepAlive
Specifies whether the system should send keepalive messages to the
other side.
If they are sent, death of the connection or crash of one
of the machines will be properly noticed.
However, this means that
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connections will die if the route is down temporarily, and some people
find it annoying.
On the other hand, if keepalives are not sent,
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sessions may hang indefinitely on the server, leaving
.Dq ghost
users and consuming server resources.
.Pp
The default is
.Dq yes
(to send keepalives), and the server will notice
if the network goes down or the client host reboots.
This avoids infinitely hanging sessions.
1999-10-28 23:15:49 +00:00
.Pp
To disable keepalives, the value should be set to
.Dq no
in both the server and the client configuration files.
.It Cm KerberosAuthentication
Specifies whether Kerberos authentication is allowed.
This can be in the form of a Kerberos ticket, or if
1999-10-28 23:15:49 +00:00
.Cm PasswordAuthentication
is yes, the password provided by the user will be validated through
- (djm) Big OpenBSD sync: - markus@cvs.openbsd.org 2000/09/30 10:27:44 [log.c] allow loglevel debug - markus@cvs.openbsd.org 2000/10/03 11:59:57 [packet.c] hmac->mac - markus@cvs.openbsd.org 2000/10/03 12:03:03 [auth-krb4.c auth-passwd.c auth-rh-rsa.c auth-rhosts.c auth-rsa.c auth1.c] move fake-auth from auth1.c to individual auth methods, disables s/key in debug-msg - markus@cvs.openbsd.org 2000/10/03 12:16:48 ssh.c do not resolve canonname, i have no idea why this was added oin ossh - markus@cvs.openbsd.org 2000/10/09 15:30:44 ssh-keygen.1 ssh-keygen.c -X now reads private ssh.com DSA keys, too. - markus@cvs.openbsd.org 2000/10/09 15:32:34 auth-options.c clear options on every call. - markus@cvs.openbsd.org 2000/10/09 15:51:00 authfd.c authfd.h interop with ssh-agent2, from <res@shore.net> - markus@cvs.openbsd.org 2000/10/10 14:20:45 compat.c use rexexp for version string matching - provos@cvs.openbsd.org 2000/10/10 22:02:18 [kex.c kex.h myproposal.h ssh.h ssh2.h sshconnect2.c sshd.c dh.c dh.h] First rough implementation of the diffie-hellman group exchange. The client can ask the server for bigger groups to perform the diffie-hellman in, thus increasing the attack complexity when using ciphers with longer keys. University of Windsor provided network, T the company. - markus@cvs.openbsd.org 2000/10/11 13:59:52 [auth-rsa.c auth2.c] clear auth options unless auth sucessfull - markus@cvs.openbsd.org 2000/10/11 14:00:27 [auth-options.h] clear auth options unless auth sucessfull - markus@cvs.openbsd.org 2000/10/11 14:03:27 [scp.1 scp.c] support 'scp -o' with help from mouring@pconline.com - markus@cvs.openbsd.org 2000/10/11 14:11:35 [dh.c] Wall - markus@cvs.openbsd.org 2000/10/11 14:14:40 [auth.h auth2.c readconf.c readconf.h readpass.c servconf.c servconf.h] [ssh.h sshconnect2.c sshd_config auth2-skey.c cli.c cli.h] add support for s/key (kbd-interactive) to ssh2, based on work by mkiernan@avantgo.com and me - markus@cvs.openbsd.org 2000/10/11 14:27:24 [auth.c auth1.c auth2.c authfile.c cipher.c cipher.h kex.c kex.h] [myproposal.h packet.c readconf.c session.c ssh.c ssh.h sshconnect1.c] [sshconnect2.c sshd.c] new cipher framework - markus@cvs.openbsd.org 2000/10/11 14:45:21 [cipher.c] remove DES - markus@cvs.openbsd.org 2000/10/12 03:59:20 [cipher.c cipher.h sshconnect1.c sshconnect2.c sshd.c] enable DES in SSH-1 clients only - markus@cvs.openbsd.org 2000/10/12 08:21:13 [kex.h packet.c] remove unused - markus@cvs.openbsd.org 2000/10/13 12:34:46 [sshd.c] Kludge for F-Secure Macintosh < 1.0.2; appro@fy.chalmers.se - markus@cvs.openbsd.org 2000/10/13 12:59:15 [cipher.c cipher.h myproposal.h rijndael.c rijndael.h] rijndael/aes support - markus@cvs.openbsd.org 2000/10/13 13:10:54 [sshd.8] more info about -V - markus@cvs.openbsd.org 2000/10/13 13:12:02 [myproposal.h] prefer no compression
2000-10-14 05:23:11 +00:00
the Kerberos KDC.
To use this option, the server needs a
Kerberos servtab which allows the verification of the KDC's identity.
Default is
1999-10-28 23:15:49 +00:00
.Dq yes .
.It Cm KerberosOrLocalPasswd
If set then if password authentication through Kerberos fails then
the password will be validated via any additional local mechanism
such as
.Pa /etc/passwd .
Default is
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.Dq yes .
.It Cm KerberosTgtPassing
Specifies whether a Kerberos TGT may be forwarded to the server.
Default is
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.Dq no ,
as this only works when the Kerberos KDC is actually an AFS kaserver.
.It Cm KerberosTicketCleanup
Specifies whether to automatically destroy the user's ticket cache
file on logout.
Default is
1999-10-28 23:15:49 +00:00
.Dq yes .
.It Cm KeyRegenerationInterval
In protocol version 1, the ephemeral server key is automatically regenerated
after this many seconds (if it has been used).
The purpose of regeneration is to prevent
1999-10-28 23:15:49 +00:00
decrypting captured sessions by later breaking into the machine and
stealing the keys.
The key is never stored anywhere.
If the value is 0, the key is never regenerated.
The default is 3600 (seconds).
1999-10-28 23:15:49 +00:00
.It Cm ListenAddress
Specifies the local addresses
.Nm
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should listen on.
The following forms may be used:
.Pp
.Bl -item -offset indent -compact
.It
.Cm ListenAddress
.Sm off
.Ar host No | Ar IPv4_addr No | Ar IPv6_addr
.Sm on
.It
.Cm ListenAddress
.Sm off
.Ar host No | Ar IPv4_addr No : Ar port
.Sm on
.It
.Cm ListenAddress
.Sm off
.Oo
.Ar host No | Ar IPv6_addr Oc : Ar port
.Sm on
.El
.Pp
If
.Ar port
is not specified,
.Nm
will listen on the address and all prior
.Cm Port
options specified. The default is to listen on all local
addresses. Multiple
.Cm ListenAddress
options are permitted. Additionally, any
.Cm Port
options must precede this option for non port qualified addresses.
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.It Cm LoginGraceTime
The server disconnects after this time if the user has not
successfully logged in.
If the value is 0, there is no time limit.
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The default is 600 (seconds).
.It Cm LogLevel
Gives the verbosity level that is used when logging messages from
.Nm sshd .
The possible values are:
QUIET, FATAL, ERROR, INFO, VERBOSE and DEBUG.
The default is INFO.
Logging with level DEBUG violates the privacy of users
and is not recommended.
.It Cm MACs
Specifies the available MAC (message authentication code) algorithms.
The MAC algorithm is used in protocol version 2
for data integrity protection.
Multiple algorithms must be comma-separated.
The default is
.Dq hmac-md5,hmac-sha1,hmac-ripemd160,hmac-sha1-96,hmac-md5-96 .
.It Cm MaxStartups
Specifies the maximum number of concurrent unauthenticated connections to the
.Nm
daemon.
Additional connections will be dropped until authentication succeeds or the
.Cm LoginGraceTime
expires for a connection.
The default is 10.
.Pp
Alternatively, random early drop can be enabled by specifying
the three colon separated values
.Dq start:rate:full
- (djm) Big OpenBSD sync: - markus@cvs.openbsd.org 2000/09/30 10:27:44 [log.c] allow loglevel debug - markus@cvs.openbsd.org 2000/10/03 11:59:57 [packet.c] hmac->mac - markus@cvs.openbsd.org 2000/10/03 12:03:03 [auth-krb4.c auth-passwd.c auth-rh-rsa.c auth-rhosts.c auth-rsa.c auth1.c] move fake-auth from auth1.c to individual auth methods, disables s/key in debug-msg - markus@cvs.openbsd.org 2000/10/03 12:16:48 ssh.c do not resolve canonname, i have no idea why this was added oin ossh - markus@cvs.openbsd.org 2000/10/09 15:30:44 ssh-keygen.1 ssh-keygen.c -X now reads private ssh.com DSA keys, too. - markus@cvs.openbsd.org 2000/10/09 15:32:34 auth-options.c clear options on every call. - markus@cvs.openbsd.org 2000/10/09 15:51:00 authfd.c authfd.h interop with ssh-agent2, from <res@shore.net> - markus@cvs.openbsd.org 2000/10/10 14:20:45 compat.c use rexexp for version string matching - provos@cvs.openbsd.org 2000/10/10 22:02:18 [kex.c kex.h myproposal.h ssh.h ssh2.h sshconnect2.c sshd.c dh.c dh.h] First rough implementation of the diffie-hellman group exchange. The client can ask the server for bigger groups to perform the diffie-hellman in, thus increasing the attack complexity when using ciphers with longer keys. University of Windsor provided network, T the company. - markus@cvs.openbsd.org 2000/10/11 13:59:52 [auth-rsa.c auth2.c] clear auth options unless auth sucessfull - markus@cvs.openbsd.org 2000/10/11 14:00:27 [auth-options.h] clear auth options unless auth sucessfull - markus@cvs.openbsd.org 2000/10/11 14:03:27 [scp.1 scp.c] support 'scp -o' with help from mouring@pconline.com - markus@cvs.openbsd.org 2000/10/11 14:11:35 [dh.c] Wall - markus@cvs.openbsd.org 2000/10/11 14:14:40 [auth.h auth2.c readconf.c readconf.h readpass.c servconf.c servconf.h] [ssh.h sshconnect2.c sshd_config auth2-skey.c cli.c cli.h] add support for s/key (kbd-interactive) to ssh2, based on work by mkiernan@avantgo.com and me - markus@cvs.openbsd.org 2000/10/11 14:27:24 [auth.c auth1.c auth2.c authfile.c cipher.c cipher.h kex.c kex.h] [myproposal.h packet.c readconf.c session.c ssh.c ssh.h sshconnect1.c] [sshconnect2.c sshd.c] new cipher framework - markus@cvs.openbsd.org 2000/10/11 14:45:21 [cipher.c] remove DES - markus@cvs.openbsd.org 2000/10/12 03:59:20 [cipher.c cipher.h sshconnect1.c sshconnect2.c sshd.c] enable DES in SSH-1 clients only - markus@cvs.openbsd.org 2000/10/12 08:21:13 [kex.h packet.c] remove unused - markus@cvs.openbsd.org 2000/10/13 12:34:46 [sshd.c] Kludge for F-Secure Macintosh < 1.0.2; appro@fy.chalmers.se - markus@cvs.openbsd.org 2000/10/13 12:59:15 [cipher.c cipher.h myproposal.h rijndael.c rijndael.h] rijndael/aes support - markus@cvs.openbsd.org 2000/10/13 13:10:54 [sshd.8] more info about -V - markus@cvs.openbsd.org 2000/10/13 13:12:02 [myproposal.h] prefer no compression
2000-10-14 05:23:11 +00:00
(e.g., "10:30:60").
.Nm
will refuse connection attempts with a probability of
.Dq rate/100
(30%)
if there are currently
.Dq start
(10)
unauthenticated connections.
The probability increases linearly and all connection attempts
are refused if the number of unauthenticated connections reaches
.Dq full
(60).
.It Cm PAMAuthenticationViaKbdInt
Specifies whether PAM challenge response authentication is allowed. This
allows the use of most PAM challenge response authentication modules, but
it will allow password authentication regardless of whether
.Cm PasswordAuthentication
is disabled.
The default is
.Dq no .
1999-10-28 23:15:49 +00:00
.It Cm PasswordAuthentication
Specifies whether password authentication is allowed.
The default is
.Dq yes .
.It Cm PermitEmptyPasswords
When password authentication is allowed, it specifies whether the
server allows login to accounts with empty password strings.
The default is
- OpenBSD CVS updates to v1.2.3 [ssh.h atomicio.c] - int atomicio -> ssize_t (for alpha). ok deraadt@ [auth-rsa.c] - delay MD5 computation until client sends response, free() early, cleanup. [cipher.c] - void* -> unsigned char*, ok niels@ [hostfile.c] - remove unused variable 'len'. fix comments. - remove unused variable [log-client.c log-server.c] - rename a cpp symbol, to avoid param.h collision [packet.c] - missing xfree() - getsockname() requires initialized tolen; andy@guildsoftware.com - use getpeername() in packet_connection_is_on_socket(), fixes sshd -i; from Holger.Trapp@Informatik.TU-Chemnitz.DE [pty.c pty.h] - register cleanup for pty earlier. move code for pty-owner handling to pty.c ok provos@, dugsong@ [readconf.c] - turn off x11-fwd for the client, too. [rsa.c] - PKCS#1 padding [scp.c] - allow '.' in usernames; from jedgar@fxp.org [servconf.c] - typo: ignore_user_known_hosts int->flag; naddy@mips.rhein-neckar.de - sync with sshd_config [ssh-keygen.c] - enable ssh-keygen -l -f ~/.ssh/known_hosts, ok deraadt@ [ssh.1] - Change invalid 'CHAT' loglevel to 'VERBOSE' [ssh.c] - suppress AAAA query host when '-4' is used; from shin@nd.net.fujitsu.co.jp - turn off x11-fwd for the client, too. [sshconnect.c] - missing xfree() - retry rresvport_af(), too. from sumikawa@ebina.hitachi.co.jp. - read error vs. "Connection closed by remote host" [sshd.8] - ie. -> i.e., - do not link to a commercial page.. - sync with sshd_config [sshd.c] - no need for poll.h; from bright@wintelcom.net - log with level log() not fatal() if peer behaves badly. - don't panic if client behaves strange. ok deraadt@ - make no-port-forwarding for RSA keys deny both -L and -R style fwding - delay close() of pty until the pty has been chowned back to root - oops, fix comment, too. - missing xfree() - move XAUTHORITY to subdir. ok dugsong@. fixes debian bug #57907, too. (http://cgi.debian.org/cgi-bin/bugreport.cgi?archive=no&bug=57907) - register cleanup for pty earlier. move code for pty-owner handling to pty.c ok provos@, dugsong@ - create x11 cookie file - fix pr 1113, fclose() -> pclose(), todo: remote popen() - version 1.2.3 - Cleaned up
2000-03-09 10:27:49 +00:00
.Dq no .
1999-10-28 23:15:49 +00:00
.It Cm PermitRootLogin
Specifies whether root can login using
1999-10-28 23:15:49 +00:00
.Xr ssh 1 .
The argument must be
.Dq yes ,
.Dq without-password ,
.Dq forced-commands-only
1999-10-28 23:15:49 +00:00
or
.Dq no .
The default is
.Dq yes .
.Pp
If this option is set to
1999-10-28 23:15:49 +00:00
.Dq without-password
password authentication is disabled for root.
1999-10-28 23:15:49 +00:00
.Pp
If this option is set to
.Dq forced-commands-only
root login with public key authentication will be allowed,
but only if the
1999-10-28 23:15:49 +00:00
.Ar command
option has been specified
1999-10-28 23:15:49 +00:00
(which may be useful for taking remote backups even if root login is
normally not allowed). All other authentication methods are disabled
for root.
.Pp
If this option is set to
.Dq no
root is not allowed to login.
.It Cm PidFile
Specifies the file that contains the process identifier of the
.Nm
daemon.
The default is
.Pa /var/run/sshd.pid .
1999-10-28 23:15:49 +00:00
.It Cm Port
Specifies the port number that
.Nm
listens on.
The default is 22.
Multiple options of this type are permitted.
See also
.Cm ListenAddress .
.It Cm PrintLastLog
Specifies whether
.Nm
should print the date and time when the user last logged in.
The default is
.Dq yes .
1999-10-28 23:15:49 +00:00
.It Cm PrintMotd
Specifies whether
.Nm
should print
1999-10-28 23:15:49 +00:00
.Pa /etc/motd
when a user logs in interactively.
(On some systems it is also printed by the shell,
1999-10-28 23:15:49 +00:00
.Pa /etc/profile ,
or equivalent.)
The default is
1999-10-28 23:15:49 +00:00
.Dq yes .
.It Cm Protocol
Specifies the protocol versions
.Nm
should support.
The possible values are
.Dq 1
and
.Dq 2 .
Multiple versions must be comma-separated.
The default is
.Dq 2,1 .
.It Cm PubkeyAuthentication
Specifies whether public key authentication is allowed.
The default is
.Dq yes .
Note that this option applies to protocol version 2 only.
.It Cm ReverseMappingCheck
Specifies whether
.Nm
should try to verify the remote host name and check that
the resolved host name for the remote IP address maps back to the
very same IP address.
The default is
.Dq no .
1999-10-28 23:15:49 +00:00
.It Cm RhostsAuthentication
Specifies whether authentication using rhosts or /etc/hosts.equiv
files is sufficient.
Normally, this method should not be permitted because it is insecure.
1999-10-28 23:15:49 +00:00
.Cm RhostsRSAAuthentication
should be used
instead, because it performs RSA-based host authentication in addition
to normal rhosts or /etc/hosts.equiv authentication.
The default is
.Dq no .
This option applies to protocol version 1 only.
1999-10-28 23:15:49 +00:00
.It Cm RhostsRSAAuthentication
Specifies whether rhosts or /etc/hosts.equiv authentication together
with successful RSA host authentication is allowed.
The default is
- OpenBSD CVS updates to v1.2.3 [ssh.h atomicio.c] - int atomicio -> ssize_t (for alpha). ok deraadt@ [auth-rsa.c] - delay MD5 computation until client sends response, free() early, cleanup. [cipher.c] - void* -> unsigned char*, ok niels@ [hostfile.c] - remove unused variable 'len'. fix comments. - remove unused variable [log-client.c log-server.c] - rename a cpp symbol, to avoid param.h collision [packet.c] - missing xfree() - getsockname() requires initialized tolen; andy@guildsoftware.com - use getpeername() in packet_connection_is_on_socket(), fixes sshd -i; from Holger.Trapp@Informatik.TU-Chemnitz.DE [pty.c pty.h] - register cleanup for pty earlier. move code for pty-owner handling to pty.c ok provos@, dugsong@ [readconf.c] - turn off x11-fwd for the client, too. [rsa.c] - PKCS#1 padding [scp.c] - allow '.' in usernames; from jedgar@fxp.org [servconf.c] - typo: ignore_user_known_hosts int->flag; naddy@mips.rhein-neckar.de - sync with sshd_config [ssh-keygen.c] - enable ssh-keygen -l -f ~/.ssh/known_hosts, ok deraadt@ [ssh.1] - Change invalid 'CHAT' loglevel to 'VERBOSE' [ssh.c] - suppress AAAA query host when '-4' is used; from shin@nd.net.fujitsu.co.jp - turn off x11-fwd for the client, too. [sshconnect.c] - missing xfree() - retry rresvport_af(), too. from sumikawa@ebina.hitachi.co.jp. - read error vs. "Connection closed by remote host" [sshd.8] - ie. -> i.e., - do not link to a commercial page.. - sync with sshd_config [sshd.c] - no need for poll.h; from bright@wintelcom.net - log with level log() not fatal() if peer behaves badly. - don't panic if client behaves strange. ok deraadt@ - make no-port-forwarding for RSA keys deny both -L and -R style fwding - delay close() of pty until the pty has been chowned back to root - oops, fix comment, too. - missing xfree() - move XAUTHORITY to subdir. ok dugsong@. fixes debian bug #57907, too. (http://cgi.debian.org/cgi-bin/bugreport.cgi?archive=no&bug=57907) - register cleanup for pty earlier. move code for pty-owner handling to pty.c ok provos@, dugsong@ - create x11 cookie file - fix pr 1113, fclose() -> pclose(), todo: remote popen() - version 1.2.3 - Cleaned up
2000-03-09 10:27:49 +00:00
.Dq no .
This option applies to protocol version 1 only.
1999-10-28 23:15:49 +00:00
.It Cm RSAAuthentication
Specifies whether pure RSA authentication is allowed.
The default is
1999-10-28 23:15:49 +00:00
.Dq yes .
This option applies to protocol version 1 only.
1999-10-28 23:15:49 +00:00
.It Cm ServerKeyBits
Defines the number of bits in the ephemeral protocol version 1 server key.
The minimum value is 512, and the default is 768.
1999-10-28 23:15:49 +00:00
.It Cm StrictModes
Specifies whether
.Nm
should check file modes and ownership of the
user's files and home directory before accepting login.
This is normally desirable because novices sometimes accidentally leave their
directory or files world-writable.
The default is
1999-10-28 23:15:49 +00:00
.Dq yes .
.It Cm Subsystem
- (djm) Big OpenBSD sync: - markus@cvs.openbsd.org 2000/09/30 10:27:44 [log.c] allow loglevel debug - markus@cvs.openbsd.org 2000/10/03 11:59:57 [packet.c] hmac->mac - markus@cvs.openbsd.org 2000/10/03 12:03:03 [auth-krb4.c auth-passwd.c auth-rh-rsa.c auth-rhosts.c auth-rsa.c auth1.c] move fake-auth from auth1.c to individual auth methods, disables s/key in debug-msg - markus@cvs.openbsd.org 2000/10/03 12:16:48 ssh.c do not resolve canonname, i have no idea why this was added oin ossh - markus@cvs.openbsd.org 2000/10/09 15:30:44 ssh-keygen.1 ssh-keygen.c -X now reads private ssh.com DSA keys, too. - markus@cvs.openbsd.org 2000/10/09 15:32:34 auth-options.c clear options on every call. - markus@cvs.openbsd.org 2000/10/09 15:51:00 authfd.c authfd.h interop with ssh-agent2, from <res@shore.net> - markus@cvs.openbsd.org 2000/10/10 14:20:45 compat.c use rexexp for version string matching - provos@cvs.openbsd.org 2000/10/10 22:02:18 [kex.c kex.h myproposal.h ssh.h ssh2.h sshconnect2.c sshd.c dh.c dh.h] First rough implementation of the diffie-hellman group exchange. The client can ask the server for bigger groups to perform the diffie-hellman in, thus increasing the attack complexity when using ciphers with longer keys. University of Windsor provided network, T the company. - markus@cvs.openbsd.org 2000/10/11 13:59:52 [auth-rsa.c auth2.c] clear auth options unless auth sucessfull - markus@cvs.openbsd.org 2000/10/11 14:00:27 [auth-options.h] clear auth options unless auth sucessfull - markus@cvs.openbsd.org 2000/10/11 14:03:27 [scp.1 scp.c] support 'scp -o' with help from mouring@pconline.com - markus@cvs.openbsd.org 2000/10/11 14:11:35 [dh.c] Wall - markus@cvs.openbsd.org 2000/10/11 14:14:40 [auth.h auth2.c readconf.c readconf.h readpass.c servconf.c servconf.h] [ssh.h sshconnect2.c sshd_config auth2-skey.c cli.c cli.h] add support for s/key (kbd-interactive) to ssh2, based on work by mkiernan@avantgo.com and me - markus@cvs.openbsd.org 2000/10/11 14:27:24 [auth.c auth1.c auth2.c authfile.c cipher.c cipher.h kex.c kex.h] [myproposal.h packet.c readconf.c session.c ssh.c ssh.h sshconnect1.c] [sshconnect2.c sshd.c] new cipher framework - markus@cvs.openbsd.org 2000/10/11 14:45:21 [cipher.c] remove DES - markus@cvs.openbsd.org 2000/10/12 03:59:20 [cipher.c cipher.h sshconnect1.c sshconnect2.c sshd.c] enable DES in SSH-1 clients only - markus@cvs.openbsd.org 2000/10/12 08:21:13 [kex.h packet.c] remove unused - markus@cvs.openbsd.org 2000/10/13 12:34:46 [sshd.c] Kludge for F-Secure Macintosh < 1.0.2; appro@fy.chalmers.se - markus@cvs.openbsd.org 2000/10/13 12:59:15 [cipher.c cipher.h myproposal.h rijndael.c rijndael.h] rijndael/aes support - markus@cvs.openbsd.org 2000/10/13 13:10:54 [sshd.8] more info about -V - markus@cvs.openbsd.org 2000/10/13 13:12:02 [myproposal.h] prefer no compression
2000-10-14 05:23:11 +00:00
Configures an external subsystem (e.g., file transfer daemon).
Arguments should be a subsystem name and a command to execute upon subsystem
request.
The command
.Xr sftp-server 8
implements the
.Dq sftp
file transfer subsystem.
By default no subsystems are defined.
Note that this option applies to protocol version 2 only.
1999-10-28 23:15:49 +00:00
.It Cm SyslogFacility
Gives the facility code that is used when logging messages from
.Nm sshd .
The possible values are: DAEMON, USER, AUTH, LOCAL0, LOCAL1, LOCAL2,
LOCAL3, LOCAL4, LOCAL5, LOCAL6, LOCAL7.
The default is AUTH.
1999-10-28 23:15:49 +00:00
.It Cm UseLogin
Specifies whether
.Xr login 1
is used for interactive login sessions.
The default is
.Dq no .
Note that
.Xr login 1
is never used for remote command execution.
Note also, that if this is enabled,
.Cm X11Forwarding
will be disabled because
.Xr login 1
does not know how to handle
.Xr xauth 1
cookies.
1999-10-28 23:15:49 +00:00
.It Cm X11DisplayOffset
Specifies the first display number available for
.Nm sshd Ns 's
X11 forwarding.
This prevents
1999-10-28 23:15:49 +00:00
.Nm
from interfering with real X11 servers.
- OpenBSD CVS updates to v1.2.3 [ssh.h atomicio.c] - int atomicio -> ssize_t (for alpha). ok deraadt@ [auth-rsa.c] - delay MD5 computation until client sends response, free() early, cleanup. [cipher.c] - void* -> unsigned char*, ok niels@ [hostfile.c] - remove unused variable 'len'. fix comments. - remove unused variable [log-client.c log-server.c] - rename a cpp symbol, to avoid param.h collision [packet.c] - missing xfree() - getsockname() requires initialized tolen; andy@guildsoftware.com - use getpeername() in packet_connection_is_on_socket(), fixes sshd -i; from Holger.Trapp@Informatik.TU-Chemnitz.DE [pty.c pty.h] - register cleanup for pty earlier. move code for pty-owner handling to pty.c ok provos@, dugsong@ [readconf.c] - turn off x11-fwd for the client, too. [rsa.c] - PKCS#1 padding [scp.c] - allow '.' in usernames; from jedgar@fxp.org [servconf.c] - typo: ignore_user_known_hosts int->flag; naddy@mips.rhein-neckar.de - sync with sshd_config [ssh-keygen.c] - enable ssh-keygen -l -f ~/.ssh/known_hosts, ok deraadt@ [ssh.1] - Change invalid 'CHAT' loglevel to 'VERBOSE' [ssh.c] - suppress AAAA query host when '-4' is used; from shin@nd.net.fujitsu.co.jp - turn off x11-fwd for the client, too. [sshconnect.c] - missing xfree() - retry rresvport_af(), too. from sumikawa@ebina.hitachi.co.jp. - read error vs. "Connection closed by remote host" [sshd.8] - ie. -> i.e., - do not link to a commercial page.. - sync with sshd_config [sshd.c] - no need for poll.h; from bright@wintelcom.net - log with level log() not fatal() if peer behaves badly. - don't panic if client behaves strange. ok deraadt@ - make no-port-forwarding for RSA keys deny both -L and -R style fwding - delay close() of pty until the pty has been chowned back to root - oops, fix comment, too. - missing xfree() - move XAUTHORITY to subdir. ok dugsong@. fixes debian bug #57907, too. (http://cgi.debian.org/cgi-bin/bugreport.cgi?archive=no&bug=57907) - register cleanup for pty earlier. move code for pty-owner handling to pty.c ok provos@, dugsong@ - create x11 cookie file - fix pr 1113, fclose() -> pclose(), todo: remote popen() - version 1.2.3 - Cleaned up
2000-03-09 10:27:49 +00:00
The default is 10.
.It Cm X11Forwarding
Specifies whether X11 forwarding is permitted.
The default is
- OpenBSD CVS updates to v1.2.3 [ssh.h atomicio.c] - int atomicio -> ssize_t (for alpha). ok deraadt@ [auth-rsa.c] - delay MD5 computation until client sends response, free() early, cleanup. [cipher.c] - void* -> unsigned char*, ok niels@ [hostfile.c] - remove unused variable 'len'. fix comments. - remove unused variable [log-client.c log-server.c] - rename a cpp symbol, to avoid param.h collision [packet.c] - missing xfree() - getsockname() requires initialized tolen; andy@guildsoftware.com - use getpeername() in packet_connection_is_on_socket(), fixes sshd -i; from Holger.Trapp@Informatik.TU-Chemnitz.DE [pty.c pty.h] - register cleanup for pty earlier. move code for pty-owner handling to pty.c ok provos@, dugsong@ [readconf.c] - turn off x11-fwd for the client, too. [rsa.c] - PKCS#1 padding [scp.c] - allow '.' in usernames; from jedgar@fxp.org [servconf.c] - typo: ignore_user_known_hosts int->flag; naddy@mips.rhein-neckar.de - sync with sshd_config [ssh-keygen.c] - enable ssh-keygen -l -f ~/.ssh/known_hosts, ok deraadt@ [ssh.1] - Change invalid 'CHAT' loglevel to 'VERBOSE' [ssh.c] - suppress AAAA query host when '-4' is used; from shin@nd.net.fujitsu.co.jp - turn off x11-fwd for the client, too. [sshconnect.c] - missing xfree() - retry rresvport_af(), too. from sumikawa@ebina.hitachi.co.jp. - read error vs. "Connection closed by remote host" [sshd.8] - ie. -> i.e., - do not link to a commercial page.. - sync with sshd_config [sshd.c] - no need for poll.h; from bright@wintelcom.net - log with level log() not fatal() if peer behaves badly. - don't panic if client behaves strange. ok deraadt@ - make no-port-forwarding for RSA keys deny both -L and -R style fwding - delay close() of pty until the pty has been chowned back to root - oops, fix comment, too. - missing xfree() - move XAUTHORITY to subdir. ok dugsong@. fixes debian bug #57907, too. (http://cgi.debian.org/cgi-bin/bugreport.cgi?archive=no&bug=57907) - register cleanup for pty earlier. move code for pty-owner handling to pty.c ok provos@, dugsong@ - create x11 cookie file - fix pr 1113, fclose() -> pclose(), todo: remote popen() - version 1.2.3 - Cleaned up
2000-03-09 10:27:49 +00:00
.Dq no .
Note that disabling X11 forwarding does not improve security in any
way, as users can always install their own forwarders.
X11 forwarding is automatically disabled if
.Cm UseLogin
is enabled.
.It Cm XAuthLocation
Specifies the location of the
.Xr xauth 1
program.
The default is
.Pa /usr/X11R6/bin/xauth .
1999-10-28 23:15:49 +00:00
.El
.Ss Time Formats
.Pp
.Nm
command-line arguments and configuration file options that specify time
may be expressed using a sequence of the form:
.Sm off
.Ar time Oo Ar qualifier Oc ,
.Sm on
where
.Ar time
is a positive integer value and
.Ar qualifier
is one of the following:
.Pp
.Bl -tag -width Ds -compact -offset indent
.It Cm <none>
seconds
.It Cm s | Cm S
seconds
.It Cm m | Cm M
minutes
.It Cm h | Cm H
hours
.It Cm d | Cm D
days
.It Cm w | Cm W
weeks
.El
.Pp
Each member of the sequence is added together to calculate
the total time value.
.Pp
Time format examples:
.Pp
.Bl -tag -width Ds -compact -offset indent
.It 600
600 seconds (10 minutes)
.It 10m
10 minutes
.It 1h30m
1 hour 30 minutes (90 minutes)
.El
1999-10-28 23:15:49 +00:00
.Sh LOGIN PROCESS
When a user successfully logs in,
.Nm
does the following:
.Bl -enum -offset indent
.It
If the login is on a tty, and no command has been specified,
prints last login time and
1999-10-28 23:15:49 +00:00
.Pa /etc/motd
(unless prevented in the configuration file or by
.Pa $HOME/.hushlogin ;
see the
.Sx FILES
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section).
.It
If the login is on a tty, records login time.
.It
Checks
.Pa /etc/nologin ;
if it exists, prints contents and quits
(unless root).
.It
Changes to run with normal user privileges.
.It
Sets up basic environment.
.It
Reads
.Pa $HOME/.ssh/environment
if it exists.
.It
Changes to user's home directory.
.It
If
.Pa $HOME/.ssh/rc
exists, runs it; else if
.Pa /etc/sshrc
1999-10-28 23:15:49 +00:00
exists, runs
it; otherwise runs xauth.
The
1999-10-28 23:15:49 +00:00
.Dq rc
files are given the X11
authentication protocol and cookie in standard input.
.It
Runs user's shell or command.
.El
.Sh AUTHORIZED_KEYS FILE FORMAT
.Pa $HOME/.ssh/authorized_keys
is the default file that lists the public keys that are
permitted for RSA authentication in protocol version 1
and for public key authentication (PubkeyAuthentication)
in protocol version 2.
.Cm AuthorizedKeysFile
may be used to specify an alternative file.
.Pp
Each line of the file contains one
1999-10-28 23:15:49 +00:00
key (empty lines and lines starting with a
.Ql #
are ignored as
comments).
Each RSA public key consists of the following fields, separated by
spaces: options, bits, exponent, modulus, comment.
Each protocol version 2 public key consists of:
options, keytype, base64 encoded key, comment.
The options fields
are optional; its presence is determined by whether the line starts
1999-10-28 23:15:49 +00:00
with a number or not (the option field never starts with a number).
The bits, exponent, modulus and comment fields give the RSA key for
protocol version 1; the
1999-10-28 23:15:49 +00:00
comment field is not used for anything (but may be convenient for the
user to identify the key).
For protocol version 2 the keytype is
.Dq ssh-dss
or
.Dq ssh-rsa .
1999-10-28 23:15:49 +00:00
.Pp
Note that lines in this file are usually several hundred bytes long
(because of the size of the RSA key modulus).
You don't want to type them in; instead, copy the
.Pa identity.pub ,
.Pa id_dsa.pub
or the
.Pa id_rsa.pub
1999-10-28 23:15:49 +00:00
file and edit it.
.Pp
The options (if present) consist of comma-separated option
specifications.
No spaces are permitted, except within double quotes.
The following option specifications are supported (note
that option keywords are case-insensitive):
1999-10-28 23:15:49 +00:00
.Bl -tag -width Ds
.It Cm from="pattern-list"
Specifies that in addition to RSA authentication, the canonical name
of the remote host must be present in the comma-separated list of
patterns
.Pf ( Ql *
and
.Ql ?
serve as wildcards).
The list may also contain
patterns negated by prefixing them with
.Ql ! ;
if the canonical host name matches a negated pattern, the key is not accepted.
The purpose
1999-10-28 23:15:49 +00:00
of this option is to optionally increase security: RSA authentication
by itself does not trust the network or name servers or anything (but
the key); however, if somebody somehow steals the key, the key
permits an intruder to log in from anywhere in the world.
This additional option makes using a stolen key more difficult (name
1999-10-28 23:15:49 +00:00
servers and/or routers would have to be compromised in addition to
just the key).
.It Cm command="command"
Specifies that the command is executed whenever this key is used for
authentication.
The command supplied by the user (if any) is ignored.
The command is run on a pty if the client requests a pty;
otherwise it is run without a tty.
If a 8-bit clean channel is required,
one must not request a pty or should specify
.Cm no-pty .
A quote may be included in the command by quoting it with a backslash.
This option might be useful
to restrict certain RSA keys to perform just a specific operation.
An example might be a key that permits remote backups but nothing else.
Note that the client may specify TCP/IP and/or X11
forwarding unless they are explicitly prohibited.
Note that this option applies to shell, command or subsystem execution.
1999-10-28 23:15:49 +00:00
.It Cm environment="NAME=value"
Specifies that the string is to be added to the environment when
logging in using this key.
Environment variables set this way
override other default environment values.
Multiple options of this type are permitted.
This option is automatically disabled if
.Cm UseLogin
is enabled.
1999-10-28 23:15:49 +00:00
.It Cm no-port-forwarding
Forbids TCP/IP forwarding when this key is used for authentication.
Any port forward requests by the client will return an error.
This might be used, e.g., in connection with the
1999-10-28 23:15:49 +00:00
.Cm command
option.
.It Cm no-X11-forwarding
Forbids X11 forwarding when this key is used for authentication.
Any X11 forward requests by the client will return an error.
.It Cm no-agent-forwarding
Forbids authentication agent forwarding when this key is used for
authentication.
.It Cm no-pty
Prevents tty allocation (a request to allocate a pty will fail).
.It Cm permitopen="host:port"
Limit local
.Li ``ssh -L''
port forwarding such that it may only connect to the specified host and
port.
IPv6 addresses can be specified with an alternative syntax:
.Ar host/port .
Multiple
.Cm permitopen
options may be applied separated by commas. No pattern matching is
performed on the specified hostnames, they must be literal domains or
addresses.
1999-10-28 23:15:49 +00:00
.El
.Ss Examples
1024 33 12121.\|.\|.\|312314325 ylo@foo.bar
.Pp
from="*.niksula.hut.fi,!pc.niksula.hut.fi" 1024 35 23.\|.\|.\|2334 ylo@niksula
.Pp
command="dump /home",no-pty,no-port-forwarding 1024 33 23.\|.\|.\|2323 backup.hut.fi
.Pp
permitopen="10.2.1.55:80",permitopen="10.2.1.56:25" 1024 33 23.\|.\|.\|2323
1999-10-28 23:15:49 +00:00
.Sh SSH_KNOWN_HOSTS FILE FORMAT
The
- Remove references to SSLeay. - Big OpenBSD CVS update - markus@cvs.openbsd.org [clientloop.c] - typo [session.c] - update proctitle on pty alloc/dealloc, e.g. w/ windows client [session.c] - update proctitle for proto 1, too [channels.h nchan.c serverloop.c session.c sshd.c] - use c-style comments - deraadt@cvs.openbsd.org [scp.c] - more atomicio - markus@cvs.openbsd.org [channels.c] - set O_NONBLOCK [ssh.1] - update AUTHOR [readconf.c ssh-keygen.c ssh.h] - default DSA key file ~/.ssh/id_dsa [clientloop.c] - typo, rm verbose debug - deraadt@cvs.openbsd.org [ssh-keygen.1] - document DSA use of ssh-keygen [sshd.8] - a start at describing what i understand of the DSA side [ssh-keygen.1] - document -X and -x [ssh-keygen.c] - simplify usage - markus@cvs.openbsd.org [sshd.8] - there is no rhosts_dsa [ssh-keygen.1] - document -y, update -X,-x [nchan.c] - fix close for non-open ssh1 channels [servconf.c servconf.h ssh.h sshd.8 sshd.c ] - s/DsaKey/HostDSAKey/, document option [sshconnect2.c] - respect number_of_password_prompts [channels.c channels.h servconf.c servconf.h session.c sshd.8] - GatewayPorts for sshd, ok deraadt@ [ssh-add.1 ssh-agent.1 ssh.1] - more doc on: DSA, id_dsa, known_hosts2, authorized_keys2 [ssh.1] - more info on proto 2 [sshd.8] - sync AUTHOR w/ ssh.1 [key.c key.h sshconnect.c] - print key type when talking about host keys [packet.c] - clear padding in ssh2 [dsa.c key.c radix.c ssh.h sshconnect1.c uuencode.c uuencode.h] - replace broken uuencode w/ libc b64_ntop [auth2.c] - log failure before sending the reply [key.c radix.c uuencode.c] - remote trailing comments before calling __b64_pton [auth2.c readconf.c readconf.h servconf.c servconf.h ssh.1] [sshconnect2.c sshd.8] - add DSAAuthetication option to ssh/sshd, document SSH2 in sshd.8 - Bring in b64_ntop and b64_pton from OpenBSD libc (bsd-base64.[ch])
2000-05-07 02:03:14 +00:00
.Pa /etc/ssh_known_hosts ,
and
.Pa $HOME/.ssh/known_hosts
files contain host public keys for all known hosts.
The global file should
be prepared by the administrator (optional), and the per-user file is
maintained automatically: whenever the user connects from an unknown host
its key is added to the per-user file.
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.Pp
Each line in these files contains the following fields: hostnames,
bits, exponent, modulus, comment.
The fields are separated by spaces.
1999-10-28 23:15:49 +00:00
.Pp
Hostnames is a comma-separated list of patterns ('*' and '?' act as
wildcards); each pattern in turn is matched against the canonical host
name (when authenticating a client) or against the user-supplied
name (when authenticating a server).
A pattern may also be preceded by
1999-10-28 23:15:49 +00:00
.Ql !
to indicate negation: if the host name matches a negated
pattern, it is not accepted (by that line) even if it matched another
pattern on the line.
.Pp
- Remove references to SSLeay. - Big OpenBSD CVS update - markus@cvs.openbsd.org [clientloop.c] - typo [session.c] - update proctitle on pty alloc/dealloc, e.g. w/ windows client [session.c] - update proctitle for proto 1, too [channels.h nchan.c serverloop.c session.c sshd.c] - use c-style comments - deraadt@cvs.openbsd.org [scp.c] - more atomicio - markus@cvs.openbsd.org [channels.c] - set O_NONBLOCK [ssh.1] - update AUTHOR [readconf.c ssh-keygen.c ssh.h] - default DSA key file ~/.ssh/id_dsa [clientloop.c] - typo, rm verbose debug - deraadt@cvs.openbsd.org [ssh-keygen.1] - document DSA use of ssh-keygen [sshd.8] - a start at describing what i understand of the DSA side [ssh-keygen.1] - document -X and -x [ssh-keygen.c] - simplify usage - markus@cvs.openbsd.org [sshd.8] - there is no rhosts_dsa [ssh-keygen.1] - document -y, update -X,-x [nchan.c] - fix close for non-open ssh1 channels [servconf.c servconf.h ssh.h sshd.8 sshd.c ] - s/DsaKey/HostDSAKey/, document option [sshconnect2.c] - respect number_of_password_prompts [channels.c channels.h servconf.c servconf.h session.c sshd.8] - GatewayPorts for sshd, ok deraadt@ [ssh-add.1 ssh-agent.1 ssh.1] - more doc on: DSA, id_dsa, known_hosts2, authorized_keys2 [ssh.1] - more info on proto 2 [sshd.8] - sync AUTHOR w/ ssh.1 [key.c key.h sshconnect.c] - print key type when talking about host keys [packet.c] - clear padding in ssh2 [dsa.c key.c radix.c ssh.h sshconnect1.c uuencode.c uuencode.h] - replace broken uuencode w/ libc b64_ntop [auth2.c] - log failure before sending the reply [key.c radix.c uuencode.c] - remote trailing comments before calling __b64_pton [auth2.c readconf.c readconf.h servconf.c servconf.h ssh.1] [sshconnect2.c sshd.8] - add DSAAuthetication option to ssh/sshd, document SSH2 in sshd.8 - Bring in b64_ntop and b64_pton from OpenBSD libc (bsd-base64.[ch])
2000-05-07 02:03:14 +00:00
Bits, exponent, and modulus are taken directly from the RSA host key; they
1999-10-28 23:15:49 +00:00
can be obtained, e.g., from
.Pa /etc/ssh_host_key.pub .
1999-10-28 23:15:49 +00:00
The optional comment field continues to the end of the line, and is not used.
.Pp
Lines starting with
.Ql #
and empty lines are ignored as comments.
.Pp
When performing host authentication, authentication is accepted if any
matching line has the proper key.
It is thus permissible (but not
1999-10-28 23:15:49 +00:00
recommended) to have several lines or different host keys for the same
names.
This will inevitably happen when short forms of host names
from different domains are put in the file.
It is possible
1999-10-28 23:15:49 +00:00
that the files contain conflicting information; authentication is
accepted if valid information can be found from either file.
.Pp
Note that the lines in these files are typically hundreds of characters
long, and you definitely don't want to type in the host keys by hand.
Rather, generate them by a script
or by taking
.Pa /etc/ssh_host_key.pub
1999-10-28 23:15:49 +00:00
and adding the host names at the front.
.Ss Examples
.Bd -literal
closenet,.\|.\|.\|,130.233.208.41 1024 37 159.\|.\|.93 closenet.hut.fi
cvs.openbsd.org,199.185.137.3 ssh-rsa AAAA1234.....=
.Ed
1999-10-28 23:15:49 +00:00
.Sh FILES
.Bl -tag -width Ds
.It Pa /etc/sshd_config
1999-10-28 23:15:49 +00:00
Contains configuration data for
.Nm sshd .
This file should be writable by root only, but it is recommended
(though not necessary) that it be world-readable.
.It Pa /etc/ssh_host_key, /etc/ssh_host_dsa_key, /etc/ssh_host_rsa_key
These three files contain the private parts of the host keys.
These files should only be owned by root, readable only by root, and not
1999-10-28 23:15:49 +00:00
accessible to others.
Note that
.Nm
does not start if this file is group/world-accessible.
.It Pa /etc/ssh_host_key.pub, /etc/ssh_host_dsa_key.pub, /etc/ssh_host_rsa_key.pub
These three files contain the public parts of the host keys.
These files should be world-readable but writable only by
root.
Their contents should match the respective private parts.
These files are not
really used for anything; they are provided for the convenience of
the user so their contents can be copied to known hosts files.
These files are created using
1999-10-28 23:15:49 +00:00
.Xr ssh-keygen 1 .
.It Pa /etc/moduli
Contains Diffie-Hellman groups used for the "Diffie-Hellman Group Exchange".
.It Pa /var/run/sshd.pid
1999-10-28 23:15:49 +00:00
Contains the process ID of the
.Nm
listening for connections (if there are several daemons running
concurrently for different ports, this contains the pid of the one
started last).
The content of this file is not sensitive; it can be world-readable.
1999-10-28 23:15:49 +00:00
.It Pa $HOME/.ssh/authorized_keys
Lists the public keys (RSA or DSA) that can be used to log into the user's account.
- Remove references to SSLeay. - Big OpenBSD CVS update - markus@cvs.openbsd.org [clientloop.c] - typo [session.c] - update proctitle on pty alloc/dealloc, e.g. w/ windows client [session.c] - update proctitle for proto 1, too [channels.h nchan.c serverloop.c session.c sshd.c] - use c-style comments - deraadt@cvs.openbsd.org [scp.c] - more atomicio - markus@cvs.openbsd.org [channels.c] - set O_NONBLOCK [ssh.1] - update AUTHOR [readconf.c ssh-keygen.c ssh.h] - default DSA key file ~/.ssh/id_dsa [clientloop.c] - typo, rm verbose debug - deraadt@cvs.openbsd.org [ssh-keygen.1] - document DSA use of ssh-keygen [sshd.8] - a start at describing what i understand of the DSA side [ssh-keygen.1] - document -X and -x [ssh-keygen.c] - simplify usage - markus@cvs.openbsd.org [sshd.8] - there is no rhosts_dsa [ssh-keygen.1] - document -y, update -X,-x [nchan.c] - fix close for non-open ssh1 channels [servconf.c servconf.h ssh.h sshd.8 sshd.c ] - s/DsaKey/HostDSAKey/, document option [sshconnect2.c] - respect number_of_password_prompts [channels.c channels.h servconf.c servconf.h session.c sshd.8] - GatewayPorts for sshd, ok deraadt@ [ssh-add.1 ssh-agent.1 ssh.1] - more doc on: DSA, id_dsa, known_hosts2, authorized_keys2 [ssh.1] - more info on proto 2 [sshd.8] - sync AUTHOR w/ ssh.1 [key.c key.h sshconnect.c] - print key type when talking about host keys [packet.c] - clear padding in ssh2 [dsa.c key.c radix.c ssh.h sshconnect1.c uuencode.c uuencode.h] - replace broken uuencode w/ libc b64_ntop [auth2.c] - log failure before sending the reply [key.c radix.c uuencode.c] - remote trailing comments before calling __b64_pton [auth2.c readconf.c readconf.h servconf.c servconf.h ssh.1] [sshconnect2.c sshd.8] - add DSAAuthetication option to ssh/sshd, document SSH2 in sshd.8 - Bring in b64_ntop and b64_pton from OpenBSD libc (bsd-base64.[ch])
2000-05-07 02:03:14 +00:00
This file must be readable by root (which may on some machines imply
it being world-readable if the user's home directory resides on an NFS
volume).
It is recommended that it not be accessible by others.
The format of this file is described above.
Users will place the contents of their
.Pa identity.pub ,
- Remove references to SSLeay. - Big OpenBSD CVS update - markus@cvs.openbsd.org [clientloop.c] - typo [session.c] - update proctitle on pty alloc/dealloc, e.g. w/ windows client [session.c] - update proctitle for proto 1, too [channels.h nchan.c serverloop.c session.c sshd.c] - use c-style comments - deraadt@cvs.openbsd.org [scp.c] - more atomicio - markus@cvs.openbsd.org [channels.c] - set O_NONBLOCK [ssh.1] - update AUTHOR [readconf.c ssh-keygen.c ssh.h] - default DSA key file ~/.ssh/id_dsa [clientloop.c] - typo, rm verbose debug - deraadt@cvs.openbsd.org [ssh-keygen.1] - document DSA use of ssh-keygen [sshd.8] - a start at describing what i understand of the DSA side [ssh-keygen.1] - document -X and -x [ssh-keygen.c] - simplify usage - markus@cvs.openbsd.org [sshd.8] - there is no rhosts_dsa [ssh-keygen.1] - document -y, update -X,-x [nchan.c] - fix close for non-open ssh1 channels [servconf.c servconf.h ssh.h sshd.8 sshd.c ] - s/DsaKey/HostDSAKey/, document option [sshconnect2.c] - respect number_of_password_prompts [channels.c channels.h servconf.c servconf.h session.c sshd.8] - GatewayPorts for sshd, ok deraadt@ [ssh-add.1 ssh-agent.1 ssh.1] - more doc on: DSA, id_dsa, known_hosts2, authorized_keys2 [ssh.1] - more info on proto 2 [sshd.8] - sync AUTHOR w/ ssh.1 [key.c key.h sshconnect.c] - print key type when talking about host keys [packet.c] - clear padding in ssh2 [dsa.c key.c radix.c ssh.h sshconnect1.c uuencode.c uuencode.h] - replace broken uuencode w/ libc b64_ntop [auth2.c] - log failure before sending the reply [key.c radix.c uuencode.c] - remote trailing comments before calling __b64_pton [auth2.c readconf.c readconf.h servconf.c servconf.h ssh.1] [sshconnect2.c sshd.8] - add DSAAuthetication option to ssh/sshd, document SSH2 in sshd.8 - Bring in b64_ntop and b64_pton from OpenBSD libc (bsd-base64.[ch])
2000-05-07 02:03:14 +00:00
.Pa id_dsa.pub
and/or
.Pa id_rsa.pub
- Remove references to SSLeay. - Big OpenBSD CVS update - markus@cvs.openbsd.org [clientloop.c] - typo [session.c] - update proctitle on pty alloc/dealloc, e.g. w/ windows client [session.c] - update proctitle for proto 1, too [channels.h nchan.c serverloop.c session.c sshd.c] - use c-style comments - deraadt@cvs.openbsd.org [scp.c] - more atomicio - markus@cvs.openbsd.org [channels.c] - set O_NONBLOCK [ssh.1] - update AUTHOR [readconf.c ssh-keygen.c ssh.h] - default DSA key file ~/.ssh/id_dsa [clientloop.c] - typo, rm verbose debug - deraadt@cvs.openbsd.org [ssh-keygen.1] - document DSA use of ssh-keygen [sshd.8] - a start at describing what i understand of the DSA side [ssh-keygen.1] - document -X and -x [ssh-keygen.c] - simplify usage - markus@cvs.openbsd.org [sshd.8] - there is no rhosts_dsa [ssh-keygen.1] - document -y, update -X,-x [nchan.c] - fix close for non-open ssh1 channels [servconf.c servconf.h ssh.h sshd.8 sshd.c ] - s/DsaKey/HostDSAKey/, document option [sshconnect2.c] - respect number_of_password_prompts [channels.c channels.h servconf.c servconf.h session.c sshd.8] - GatewayPorts for sshd, ok deraadt@ [ssh-add.1 ssh-agent.1 ssh.1] - more doc on: DSA, id_dsa, known_hosts2, authorized_keys2 [ssh.1] - more info on proto 2 [sshd.8] - sync AUTHOR w/ ssh.1 [key.c key.h sshconnect.c] - print key type when talking about host keys [packet.c] - clear padding in ssh2 [dsa.c key.c radix.c ssh.h sshconnect1.c uuencode.c uuencode.h] - replace broken uuencode w/ libc b64_ntop [auth2.c] - log failure before sending the reply [key.c radix.c uuencode.c] - remote trailing comments before calling __b64_pton [auth2.c readconf.c readconf.h servconf.c servconf.h ssh.1] [sshconnect2.c sshd.8] - add DSAAuthetication option to ssh/sshd, document SSH2 in sshd.8 - Bring in b64_ntop and b64_pton from OpenBSD libc (bsd-base64.[ch])
2000-05-07 02:03:14 +00:00
files into this file, as described in
.Xr ssh-keygen 1 .
.It Pa "/etc/ssh_known_hosts" and "$HOME/.ssh/known_hosts"
These files are consulted when using rhosts with RSA host
authentication or protocol version 2 hostbased authentication
to check the public key of the host.
The key must be listed in one of these files to be accepted.
The client uses the same files
to verify that it is connecting to the correct remote host.
These files should be writable only by root/the owner.
.Pa /etc/ssh_known_hosts
1999-10-28 23:15:49 +00:00
should be world-readable, and
.Pa $HOME/.ssh/known_hosts
can but need not be world-readable.
.It Pa /etc/nologin
If this file exists,
1999-10-28 23:15:49 +00:00
.Nm
refuses to let anyone except root log in.
The contents of the file
1999-10-28 23:15:49 +00:00
are displayed to anyone trying to log in, and non-root connections are
refused.
The file should be world-readable.
1999-10-28 23:15:49 +00:00
.It Pa /etc/hosts.allow, /etc/hosts.deny
Access controls that should be enforced by tcp-wrappers are defined here.
Further details are described in
1999-10-28 23:15:49 +00:00
.Xr hosts_access 5 .
.It Pa $HOME/.rhosts
This file contains host-username pairs, separated by a space, one per
line.
The given user on the corresponding host is permitted to log in
without password.
The same file is used by rlogind and rshd.
1999-10-28 23:15:49 +00:00
The file must
be writable only by the user; it is recommended that it not be
accessible by others.
.Pp
If is also possible to use netgroups in the file.
Either host or user
1999-10-28 23:15:49 +00:00
name may be of the form +@groupname to specify all hosts or all users
in the group.
.It Pa $HOME/.shosts
For ssh,
this file is exactly the same as for
.Pa .rhosts .
However, this file is
not used by rlogin and rshd, so using this permits access using SSH only.
.It Pa /etc/hosts.equiv
1999-10-28 23:15:49 +00:00
This file is used during
.Pa .rhosts
authentication.
In the simplest form, this file contains host names, one per line.
Users on
1999-10-28 23:15:49 +00:00
those hosts are permitted to log in without a password, provided they
have the same user name on both machines.
The host name may also be
1999-10-28 23:15:49 +00:00
followed by a user name; such users are permitted to log in as
.Em any
user on this machine (except root).
Additionally, the syntax
1999-10-28 23:15:49 +00:00
.Dq +@group
can be used to specify netgroups.
Negated entries start with
1999-10-28 23:15:49 +00:00
.Ql \&- .
.Pp
If the client host/user is successfully matched in this file, login is
automatically permitted provided the client and server user names are the
same.
Additionally, successful RSA host authentication is normally required.
This file must be writable only by root; it is recommended
1999-10-28 23:15:49 +00:00
that it be world-readable.
.Pp
.Sy "Warning: It is almost never a good idea to use user names in"
.Pa hosts.equiv .
Beware that it really means that the named user(s) can log in as
.Em anybody ,
which includes bin, daemon, adm, and other accounts that own critical
binaries and directories.
Using a user name practically grants the user root access.
The only valid use for user names that I can think
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of is in negative entries.
.Pp
Note that this warning also applies to rsh/rlogin.
.It Pa /etc/shosts.equiv
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This is processed exactly as
.Pa /etc/hosts.equiv .
However, this file may be useful in environments that want to run both
rsh/rlogin and ssh.
.It Pa $HOME/.ssh/environment
This file is read into the environment at login (if it exists).
It can only contain empty lines, comment lines (that start with
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.Ql # ) ,
and assignment lines of the form name=value.
The file should be writable
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only by the user; it need not be readable by anyone else.
.It Pa $HOME/.ssh/rc
If this file exists, it is run with /bin/sh after reading the
environment files but before starting the user's shell or command.
If X11 spoofing is in use, this will receive the "proto cookie" pair in
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standard input (and
.Ev DISPLAY
in environment).
This must call
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.Xr xauth 1
in that case.
.Pp
The primary purpose of this file is to run any initialization routines
which may be needed before the user's home directory becomes
accessible; AFS is a particular example of such an environment.
.Pp
This file will probably contain some initialization code followed by
something similar to:
.Bd -literal
if read proto cookie; then
echo add $DISPLAY $proto $cookie | xauth -q -
fi
.Ed
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.Pp
If this file does not exist,
.Pa /etc/sshrc
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is run, and if that
does not exist either, xauth is used to store the cookie.
.Pp
This file should be writable only by the user, and need not be
readable by anyone else.
.It Pa /etc/sshrc
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Like
.Pa $HOME/.ssh/rc .
This can be used to specify
machine-specific login-time initializations globally.
This file should be writable only by root, and should be world-readable.
.El
- (djm) Merge OpenBSD changes: - markus@cvs.openbsd.org 2000/11/06 16:04:56 [channels.c channels.h clientloop.c nchan.c serverloop.c] [session.c ssh.c] agent forwarding and -R for ssh2, based on work from jhuuskon@messi.uku.fi - markus@cvs.openbsd.org 2000/11/06 16:13:27 [ssh.c sshconnect.c sshd.c] do not disabled rhosts(rsa) if server port > 1024; from pekkas@netcore.fi - markus@cvs.openbsd.org 2000/11/06 16:16:35 [sshconnect.c] downgrade client to 1.3 if server is 1.4; help from mdb@juniper.net - markus@cvs.openbsd.org 2000/11/09 18:04:40 [auth1.c] typo; from mouring@pconline.com - markus@cvs.openbsd.org 2000/11/12 12:03:28 [ssh-agent.c] off-by-one when removing a key from the agent - markus@cvs.openbsd.org 2000/11/12 12:50:39 [auth-rh-rsa.c auth2.c authfd.c authfd.h] [authfile.c hostfile.c kex.c kex.h key.c key.h myproposal.h] [readconf.c readconf.h rsa.c rsa.h servconf.c servconf.h ssh-add.c] [ssh-agent.c ssh-keygen.1 ssh-keygen.c ssh.1 ssh.c ssh_config] [sshconnect1.c sshconnect2.c sshd.8 sshd.c sshd_config ssh-dss.c] [ssh-dss.h ssh-rsa.c ssh-rsa.h dsa.c dsa.h] add support for RSA to SSH2. please test. there are now 3 types of keys: RSA1 is used by ssh-1 only, RSA and DSA are used by SSH2. you can use 'ssh-keygen -t rsa -f ssh2_rsa_file' to generate RSA keys for SSH2 and use the RSA keys for hostkeys or for user keys. SSH2 RSA or DSA keys are added to .ssh/authorised_keys2 as before. - (djm) Fix up Makefile and Redhat init script to create RSA host keys - (djm) Change to interim version
2000-11-13 11:57:25 +00:00
.Sh AUTHORS
OpenSSH is a derivative of the original and free
ssh 1.2.12 release by Tatu Ylonen.
Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos,
Theo de Raadt and Dug Song
removed many bugs, re-added newer features and
created OpenSSH.
Markus Friedl contributed the support for SSH
protocol versions 1.5 and 2.0.
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.Sh SEE ALSO
.Xr scp 1 ,
.Xr sftp 1 ,
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.Xr ssh 1 ,
.Xr ssh-add 1 ,
.Xr ssh-agent 1 ,
.Xr ssh-keygen 1 ,
.Xr login.conf 5 ,
.Xr moduli 5 ,
.Xr sftp-server 8
.Rs
.%A T. Ylonen
.%A T. Kivinen
.%A M. Saarinen
.%A T. Rinne
.%A S. Lehtinen
.%T "SSH Protocol Architecture"
.%N draft-ietf-secsh-architecture-09.txt
.%D July 2001
.%O work in progress material
.Re
.Rs
.%A M. Friedl
.%A N. Provos
.%A W. A. Simpson
.%T "Diffie-Hellman Group Exchange for the SSH Transport Layer Protocol"
.%N draft-ietf-secsh-dh-group-exchange-01.txt
.%D April 2001
.%O work in progress material
.Re