1 .\" Copyright (c) 1995 Peter Tobias <tobias@et-inf.fho-emden.de>
3 .\" %%%LICENSE_START(GPL_NOVERSION_ONELINE)
4 .\" This file may be distributed under the GNU General Public License.
6 .TH HOSTS.EQUIV 5 2020-06-09 "Linux" "Linux Programmer's Manual"
8 hosts.equiv \- list of hosts and users that are granted "trusted"
10 command access to your system
14 allows or denies hosts and users to use
15 the \fBr\fP-commands (e.g.,
23 The file uses the following format:
25 \fI+|[\-]hostname|+@netgroup|\-@netgroup\fP \fI[+|[\-]username|+@netgroup|\-@netgroup]\fP
29 is the name of a host which is logically equivalent
31 Users logged into that host are allowed to access
32 like-named user accounts on the local host without supplying a password.
35 may be (optionally) preceded by a plus (+) sign.
36 If the plus sign is used alone, it allows any host to access your system.
37 You can explicitly deny access to a host by preceding the
40 Users from that host must always supply additional credentials,
41 including possibly a password.
42 For security reasons you should always
43 use the FQDN of the hostname and not the short hostname.
47 entry grants a specific user access to all user
48 accounts (except root) without supplying a password.
50 user is NOT restricted to like-named accounts.
54 be (optionally) preceded by a plus (+) sign.
55 You can also explicitly
56 deny access to a specific user by preceding the
60 This says that the user is not trusted no matter
61 what other entries for that host exist.
63 Netgroups can be specified by preceding the netgroup by an @ sign.
65 Be extremely careful when using the plus (+) sign.
66 A simple typographical
67 error could result in a standalone plus sign.
68 A standalone plus sign is
69 a wildcard character that means "any host"!
73 Some systems will honor the contents of this file only when it has owner
74 root and no write permission for anybody else.
76 paranoid systems even require that there be no other hard links to the file.
78 Modern systems use the Pluggable Authentication Modules library (PAM).
79 With PAM a standalone plus sign is considered a wildcard
80 character which means "any host" only when the word
82 is added to the auth component line in your PAM file for
83 the particular service
84 .RB "(e.g., " rlogin ).
86 Below are some example
92 Allow any user to log in from any host:
98 with a matching local account to log in:
104 is never a valid syntax,
105 including attempting to specify that any user from the host is allowed.
113 Note: this is distinct from the previous example
114 since it does not require a matching local account.
120 to log in as any non-root user:
124 Allow all users with matching local accounts from
139 is never a valid syntax,
140 including attempting to specify that a particular user from the host
143 Allow all users with matching local accounts on all hosts in a
148 Disallow all users on all hosts in a
157 as any non-root user:
161 Allow all users with matching local accounts on all hosts in a
169 Note: the deny statements must always precede the allow statements because
170 the file is processed sequentially until the first matching rule is found.