man > hosts.equiv(5)

hosts.equiv(5)                           File Formats 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  with‐
       out  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  rea‐
       sons 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 ac‐
       cess 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).

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 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)

Linux man-pages 6.7                          2023-10-31                               hosts.equiv(5)