183 lines
5.4 KiB
Groff
183 lines
5.4 KiB
Groff
.\" $NetBSD: hosts.equiv.5,v 1.4 2000/11/17 10:14:18 lukem Exp $
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.\"
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.\" Copyright (c) 1997 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the NetBSD
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.\" Foundation, Inc. and its contributors.
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.\" 4. Neither the name of The NetBSD Foundation nor the names of its
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.\" contributors may be used to endorse or promote products derived
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.\" from this software without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd November 26, 1997
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.Dt HOSTS.EQUIV 5
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.Os
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.Sh NAME
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.Nm hosts.equiv ,
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.Nm .rhosts
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.Nd trusted remote hosts and host-user pairs
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.Sh DESCRIPTION
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The
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.Nm hosts.equiv
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and
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.Nm .rhosts
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files list hosts and users which are
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.Dq trusted
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by the local host when a connection is made via
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.Xr rlogind 8 ,
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.Xr rshd 8 ,
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or any other server that uses
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.Xr ruserok 3 .
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This mechanism bypasses password checks, and is required for access via
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.Xr rsh 1 .
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.Pp
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Each line of these files has the format:
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.Pp
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.Bd -unfilled -offset indent -compact
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hostname [username]
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.Ed
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.Pp
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The
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.Em hostname
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may be specified as a host name (typically a fully qualified host
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name in a DNS environment) or address,
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.Dq Li +@netgroup
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(from which only the host names are checked),
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or a
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.Dq Li \&+
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wildcard (allow all hosts).
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.Pp
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The
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.Em username ,
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if specified, may be given as a user name on the remote host,
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.Dq Li +@netgroup
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(from which only the user names are checked),
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or a
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.Dq Li \&+
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wildcard (allow all remote users).
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.Pp
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If a
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.Em username
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is specified, only that user from the specified host may login to the
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local machine. If a
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.Em username
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is not specified, any user may login with the same user name.
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.Sh EXAMPLES
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.Li somehost
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.Bd -filled -offset indent -compact
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A common usage: users on
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.Em somehost
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may login to the local host as the same user name.
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.Ed
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.Li somehost username
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.Bd -filled -offset indent -compact
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The user
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.Em username
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on
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.Em somehost
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may login to the local host. If specified in
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.Em /etc/hosts.equiv ,
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the user may login with only the same user name.
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.Ed
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.Li +@anetgroup username
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.Bd -filled -offset indent -compact
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The user
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.Em username
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may login to the local host from any machine listed in the netgroup
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.Em anetgroup .
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.Ed
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.Bd -literal -compact
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+
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+ +
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.Ed
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.Bd -filled -offset indent -compact
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Two severe security hazards. In the first case, allows a user on any
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machine to login to the local host as the same user name. In the second
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case, allows any user on any machine to login to the local host (as any
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user, if in
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.Em /etc/hosts.equiv ) .
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.Ed
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.Sh WARNINGS
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The username checks provided by this mechanism are
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.Em not
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secure, as the remote user name is received by the server unchecked
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for validity. Therefore this mechanism should only be used
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in an environment where all hosts are completely trusted.
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.Pp
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A numeric host address instead of a host name can help security
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considerations somewhat; the address is then used directly by
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.Xr iruserok 3 .
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.Pp
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When a username (or netgroup, or +) is specified in
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.Em /etc/hosts.equiv ,
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that user (or group of users, or all users, respectively) may login to
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the local host as
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.Em any local user .
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Usernames in
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.Em /etc/hosts.equiv
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should therefore be used with extreme caution, or not at all.
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.Pp
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A
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.Em .rhosts
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file must be owned by the user whose home directory it resides in, and
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must be writable only by that user.
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.Pp
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Logins as root only check root's
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.Em .rhosts
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file; the
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.Em /etc/hosts.equiv
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file is not checked for security. Access permitted through root's
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.Em .rhosts
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file is typically only for
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.Xr rsh 1 ,
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as root must still login on the console for an interactive login such as
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.Xr rlogin 1 .
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.Sh FILES
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.Bl -tag -width /etc/hosts.equiv -compact
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.It Pa /etc/hosts.equiv
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Global trusted host-user pairs list
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.It Pa ~/.rhosts
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Per-user trusted host-user pairs list
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.El
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.Sh SEE ALSO
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.Xr rcp 1 ,
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.Xr rlogin 1 ,
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.Xr rsh 1 ,
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.Xr rcmd 3 ,
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.Xr ruserok 3 ,
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.Xr netgroup 5
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.Re
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.Sh HISTORY
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The
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.Nm .rhosts
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file format appeared in
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.Bx 4.2 .
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.Sh BUGS
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The
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.Xr ruserok 3
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implementation currently skips negative entries (preceded with a
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.Dq Li \&-
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sign) and does not treat them as ``short-circuit'' negative entries.
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