NAME | DESCRIPTION | FILES | NOTES | EXAMPLE | SEE ALSO | COLOPHON

HOSTS.EQUIV(5)            Linux Programmer's Manual           HOSTS.EQUIV(5)

NAME         top

       hosts.equiv  -  list  of hosts and users that are granted "trusted" r
       command access to your system

DESCRIPTION         top

       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|-@netgroup]

       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 credentials, 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
       typographical error could result in a standalone plus sign.  A
       standalone plus sign is a wildcard character that means "any host"!

FILES         top

       /etc/hosts.equiv

NOTES         top

       Some systems will honor the contents of this file only when it has
       owner root and no write permission for anybody else.  Some
       exceptionally paranoid 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).

EXAMPLE         top

       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
       require 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
       attempting 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
       because the file is processed sequentially until the first matching
       rule is found.

SEE ALSO         top

       rhosts(5), rlogind(8), rshd(8)

COLOPHON         top

       This page is part of release 4.08 of the Linux man-pages project.  A
       description of the project, information about reporting bugs, and the
       latest version of this page, can be found at
       https://www.kernel.org/doc/man-pages/.

Linux                            2015-07-23                   HOSTS.EQUIV(5)