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
       This page is part of release 4.10 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)