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NAME    [Toc]    [Back]

       resolv+ - enhanced DNS resolver library

DESCRIPTION    [Toc]    [Back]

       Resolv+	is  a  modified  version  of  the  standard Berkeley BIND host
       resolver library.  Enhancements include support for  host  lookups  via
       the  Internet  Domain Name System (DNS), the /etc/hosts file, and Sun's
       Network Information Service (NIS).

       The programmer interface to the resolv+ routines is identical  to  that
       of  the	standard  resolver  library.   For further information see the
       appropriate manual pages.

CONFIGURATION    [Toc]    [Back]

       As with the standard resolver library, the file	/etc/resolv.conf  must
       be  set	up  before  the  resolver can function.  In addition, the file
       /etc/host.conf contains configuration information specific to  resolv+.

       The  host.conf  file should contain one configuration keyword per line,
       followed by appropriate configuration information.  The keywords recognized
  are order , trim , multi , nospoof , and reorder .  Each keyword
       is described seperately below.

       order  This keyword specifies how host lookups are to be performed.  It
	      should  be  followed by one or more lookup methods, seperated by
	      commas.  Valid methods are bind , hosts and nis .

       trim   This keyword may be listed more than once.  Each time it	should
	      be followed by a single domain name, with the leading dot.  When
	      set, the resolv+	library  will  automatically  trim  the  given
	      domain name from the end of any hostname resolved via DNS.  This
	      is intended for use with	local  hosts  and  domains.   (Related
	      note:  trim  will  not  affect hostnames gathered via NIS or the
	      hosts file.  Care should be taken to insure that the first hostname
 for each entry in the hosts file is fully qualified or nonqualified,
 as appropriate for the local installation.)

       multi  Valid values are on and off .   If  set  to  "on,"  the  resolv+
	      library  will return all valid addresses for a host that appears
	      in the /etc/hosts file, instead of only the first.  This is  off
	      by  default,  as	it may cause a substantial performance loss at
	      sites with large hosts files.

	      Valid values are on and off .   If  set  to  "on,"  the  resolv+
	      library will attempt to prevent hostname spoofing to enhance the
	      security of rlogin and rsh.  It works as follows: after performing
  a  host  address  lookup,  resolv+  will perform a hostname
	      lookup for that address.	If the two hostnames do not match, the
	      query will fail.

       alert  If  this	option	is  set to "on" and the nospoof option is also
	      set, resolv+ will log a warning of  the  error  via  the	syslog
	      facility.  The default value is off.

	      Valid  values  are  on  and  off .  If set to "on," resolv+ will
	      attempt to reorder host addresses so that local addresses (i.e.,
	      on  the  same subnet) are listed first when a gethostbyname() is
	      performed.  Reordering is done  for  all	lookup	methods.   The
	      default value is off.


       The  following  environment  variables may be set to override resolv+'s
       configured behavior:

	      If set, it will override the default filename ("/etc/host.conf")
	      for the resolv+ configuration file.

	      If set, will override the "order" keyword in the host.conf file.

	      If set, will override the spoof check flag.   Valid  values  are
	      "off"  to  disable checking, "warn" to enable checking and warning,
 and "warn off" to enable checking but not warning.

	      If set, contains a list of domains to trim  that	will  augment,
	      not supersede, the list in the host.conf file.

	      If  set,	contains  a list of domains to trim that will override
	      those in the host.conf file.

	      If set, overrides the "multi" keyword in the host.conf file.

	      If set, overrides the "reorder" keyword in the host.conf file.

FILES    [Toc]    [Back]

       /etc/host.conf, /etc/hosts

BUGS    [Toc]    [Back]

       Quite possibly.

AUTHOR    [Toc]    [Back]

       The original BIND resolver library comes from the University  of  California
  at  Berkeley's  Computer  Science Research Group.  The original
       resolv+ modifications were made by Bill	Wisner	<wisner@uunet.UU.NET>.
       Bug  fixes  and enhancements were contributed by Patrick Gosling, Chris
       Metcalf, John DiMarco and J.  Porter  Clark,  John  P.  Rouillard,  Dan
       O'Neill and Tom Limoncelli.

SEE ALSO    [Toc]    [Back]

       resolver(3), resolver(5), hosts(5), hostname(7), named(8)

				August 19, 1992 		    RESOLV+(8)
[ Back ]
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