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).

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 6.9.1                              2024-05-02                                     hosts.equiv(5)