.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
.\"
-.\" $OpenBSD: ssh.1,v 1.194 2004/08/12 21:41:13 jakob Exp $
+.\" $OpenBSD: ssh.1,v 1.195 2004/08/26 16:00:55 markus Exp $
.Dd September 25, 1999
.Dt SSH 1
.Os
.Ar command
is executed on the remote host instead of a login shell.
.Ss SSH protocol version 1
-First, if the machine the user logs in from is listed in
+The first authentication method is the
+.Em rhosts
+or
+.Em hosts.equiv
+method combined with RSA-based host authentication.
+If the machine the user logs in from is listed in
.Pa /etc/hosts.equiv
or
.Pa /etc/shosts.equiv
on the remote machine, and the user names are
-the same on both sides, the user is immediately permitted to log in.
-Second, if
-.Pa .rhosts
+the same on both sides, or if the files
+.Pa $HOME/.rhosts
or
-.Pa .shosts
-exists in the user's home directory on the
-remote machine and contains a line containing the name of the client
+.Pa $HOME/.shosts
+exist in the user's home directory on the
+remote machine and contain a line containing the name of the client
machine and the name of the user on that machine, the user is
-permitted to log in.
-This form of authentication alone is normally not
-allowed by the server because it is not secure.
-.Pp
-The second authentication method is the
-.Em rhosts
-or
-.Em hosts.equiv
-method combined with RSA-based host authentication.
-It means that if the login would be permitted by
-.Pa $HOME/.rhosts ,
-.Pa $HOME/.shosts ,
-.Pa /etc/hosts.equiv ,
-or
-.Pa /etc/shosts.equiv ,
-and if additionally the server can verify the client's
+considered for log in.
+Additionally, if the server can verify the client's
host key (see
.Pa /etc/ssh/ssh_known_hosts
and
and the rlogin/rsh protocol in general, are inherently insecure and should be
disabled if security is desired.]
.Pp
-As a third authentication method,
+As a second authentication method,
.Nm
supports RSA based authentication.
The scheme is based on public-key cryptography: there are cryptosystems
file, and has one key
per line, though the lines can be very long).
After this, the user can log in without giving the password.
-RSA authentication is much more secure than
-.Em rhosts
-authentication.
.Pp
The most convenient way to use RSA authentication may be with an
authentication agent.
is not setuid root.
.It Pa $HOME/.rhosts
This file is used in
-.Em rhosts
+.Cm RhostsRSAAuthentication
+and
+.Cm HostbasedAuthentication
authentication to list the
host/user pairs that are permitted to log in.
(Note that this file is
permission for most machines is read/write for the user, and not
accessible by others.
.Pp
-Note that by default
+Note that
.Xr sshd 8
-will be installed so that it requires successful RSA host
-authentication before permitting
-.Em rhosts
-authentication.
+allows authentication only in combination with client host key
+authentication before permitting log in.
If the server machine does not have the client's host key in
.Pa /etc/ssh/ssh_known_hosts ,
it can be stored in
This file is used exactly the same way as
.Pa .rhosts .
The purpose for
-having this file is to be able to use rhosts authentication with
-.Nm
-without permitting login with
+having this file is to be able to use
+.Cm RhostsRSAAuthentication
+and
+.Cm HostbasedAuthentication
+authentication without permitting login with
.Xr rlogin
or
.Xr rsh 1 .
.It Pa /etc/hosts.equiv
This file is used during
-.Em rhosts
+.Cm RhostsRSAAuthentication
+and
+.Cm HostbasedAuthentication
authentication.
It contains
canonical hosts names, one per line (the full format is described in the
If the client host is found in this file, login is
automatically permitted provided client and server user names are the
same.
-Additionally, successful RSA host authentication is normally
-required.
+Additionally, successful client host key authentication is required.
This file should only be writable by root.
.It Pa /etc/shosts.equiv
This file is processed exactly as
andersk / openssh.git / blobdiff