hosts.equiv(5) File Formats Manual hosts.equiv(5)
NAME
hosts.equiv - list of hosts and users that are granted "trusted" r com-
mand access to your system
DESCRIPTION
The file /etc/hosts.equiv allows or denies hosts and users to use the r-
commands (e.g., rlogin, rsh, or rcp) without supplying a password.
The file uses the following format:
+|[-]hostname|+@netgroup|-@netgroup [+|[-]username|+@netgroup|-@net-
group]
The hostname is the name of a host which is logically equivalent to the
local host. Users logged into that host are allowed to access like-
named user accounts on the local host without supplying a password. The
hostname may be (optionally) preceded by a plus (+) sign. If the plus
sign is used alone, it allows any host to access your system. You can
explicitly deny access to a host by preceding the hostname by a minus
(-) sign. Users from that host must always supply additional creden-
tials, including possibly a password. For security reasons you should
always use the FQDN of the hostname and not the short hostname.
The username entry grants a specific user access to all user accounts
(except root) without supplying a password. That means the user is NOT
restricted to like-named accounts. The username may be (optionally)
preceded by a plus (+) sign. You can also explicitly deny access to a
specific user by preceding the username with a minus (-) sign. This
says that the user is not trusted no matter what other entries for that
host exist.
Netgroups can be specified by preceding the netgroup by an @ sign.
Be extremely careful when using the plus (+) sign. A simple typographi-
cal error could result in a standalone plus sign. A standalone plus
sign is a wildcard character that means "any host"!
FILES
/etc/hosts.equiv
NOTES
Some systems will honor the contents of this file only when it has owner
root and no write permission for anybody else. Some exceptionally para-
noid systems even require that there be no other hard links to the file.
Modern systems use the Pluggable Authentication Modules library (PAM).
With PAM a standalone plus sign is considered a wildcard character which
means "any host" only when the word promiscuous is added to the auth
component line in your PAM file for the particular service (e.g.,
rlogin).
EXAMPLES
Below are some example /etc/host.equiv or ~/.rhosts files.
Allow any user to log in from any host:
+
Allow any user from host with a matching local account to log in:
host
Note: the use of +host is never a valid syntax, including attempting to
specify that any user from the host is allowed.
Allow any user from host to log in:
host +
Note: this is distinct from the previous example since it does not re-
quire a matching local account.
Allow user from host to log in as any non-root user:
host user
Allow all users with matching local accounts from host to log in except
for baduser:
host -baduser
host
Deny all users from host:
-host
Note: the use of -host -user is never a valid syntax, including attempt-
ing to specify that a particular user from the host is not trusted.
Allow all users with matching local accounts on all hosts in a netgroup:
+@netgroup
Disallow all users on all hosts in a netgroup:
-@netgroup
Allow all users in a netgroup to log in from host as any non-root user:
host +@netgroup
Allow all users with matching local accounts on all hosts in a netgroup
except baduser:
+@netgroup -baduser
+@netgroup
Note: the deny statements must always precede the allow statements be-
cause the file is processed sequentially until the first matching rule
is found.
SEE ALSO
rhosts(5), rlogind(8), rshd(8)
Linux man-pages 6.9.1 2024-05-02 hosts.equiv(5)
Generated by dwww version 1.16 on Tue Dec 16 07:03:00 CET 2025.