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HOSTS.EQUIV(5)             Linux Programmer's 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
       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 typograph-
       ical  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 exception-
       ally 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  net-
       group:
           +@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
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       latest    version    of    this    page,    can     be     found     at
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Linux                             2015-07-23                    HOSTS.EQUIV(5)