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

NAME

       hosts.equiv - list of hosts and users that are granted "trusted" r command 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|-@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

       /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
       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

       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

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

COLOPHON

       This  page is part of release 4.15 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)