1HOSTS.EQUIV(5) Linux Programmer's Manual HOSTS.EQUIV(5)
2
6 hosts.equiv - list of hosts and users that are granted "trusted" r com‐
7 mand access to your system
8
10 The file /etc/hosts.equiv allows or denies hosts and users to use the
11 r-commands (e.g., rlogin, rsh, or rcp) without supplying a password.
12 The file uses the following format:
14 +|[-]hostname|+@netgroup|-@netgroup [+|[-]username|+@netgroup|-@net‐
16 group]
17 The hostname is the name of a host which is logically equivalent to the
19 local host. Users logged into that host are allowed to access like-
20 named user accounts on the local host without supplying a password.
21 The hostname may be (optionally) preceded by a plus (+) sign. If the
22 plus sign is used alone, it allows any host to access your system. You
23 can explicitly deny access to a host by preceding the hostname by a mi‐
24 nus (-) sign. Users from that host must always supply additional cre‐
25 dentials, including possibly a password. For security reasons you
26 should always use the FQDN of the hostname and not the short hostname.
27 The username entry grants a specific user access to all user accounts
29 (except root) without supplying a password. That means the user is NOT
30 restricted to like-named accounts. The username may be (optionally)
31 preceded by a plus (+) sign. You can also explicitly deny access to a
32 specific user by preceding the username with a minus (-) sign. This
33 says that the user is not trusted no matter what other entries for that
34 host exist.
35 Netgroups can be specified by preceding the netgroup by an @ sign.
37 Be extremely careful when using the plus (+) sign. A simple typograph‐
39 ical error could result in a standalone plus sign. A standalone plus
40 sign is a wildcard character that means "any host"!
41
43 /etc/hosts.equiv
44
46 Some systems will honor the contents of this file only when it has
47 owner root and no write permission for anybody else. Some exception‐
48 ally paranoid systems even require that there be no other hard links to
49 the file.
50 Modern systems use the Pluggable Authentication Modules library (PAM).
52 With PAM a standalone plus sign is considered a wildcard character
53 which means "any host" only when the word promiscuous is added to the
54 auth component line in your PAM file for the particular service (e.g.,
55 rlogin).
56
58 Below are some example /etc/host.equiv or ~/.rhosts files.
59 Allow any user to log in from any host:
61 +
63 Allow any user from host with a matching local account to log in:
65 host
67 Note: the use of +host is never a valid syntax, including attempting to
69 specify that any user from the host is allowed.
70 Allow any user from host to log in:
72 host +
74 Note: this is distinct from the previous example since it does not re‐
76 quire a matching local account.
77 Allow user from host to log in as any non-root user:
79 host user
81 Allow all users with matching local accounts from host to log in except
83 for baduser:
84 host -baduser
86 host
87 Deny all users from host:
89 -host
91 Note: the use of -host -user is never a valid syntax, including at‐
93 tempting to specify that a particular user from the host is not
94 trusted.
95 Allow all users with matching local accounts on all hosts in a net‐
97 group:
98 +@netgroup
100 Disallow all users on all hosts in a netgroup:
102 -@netgroup
104 Allow all users in a netgroup to log in from host as any non-root user:
106 host +@netgroup
108 Allow all users with matching local accounts on all hosts in a netgroup
110 except baduser:
111 +@netgroup -baduser
113 +@netgroup
114 Note: the deny statements must always precede the allow statements be‐
116 cause the file is processed sequentially until the first matching rule
117 is found.
118
120 rhosts(5), rlogind(8), rshd(8)
121
123 This page is part of release 5.10 of the Linux man-pages project. A
124 description of the project, information about reporting bugs, and the
125 latest version of this page, can be found at
126 https://www.kernel.org/doc/man-pages/.
127Linux 2020-06-09 HOSTS.EQUIV(5)