


RESOLV+(8)                                             RESOLV+(8)


NNAAMMEE
       resolv+ - enhanced DNS resolver library

DDEESSCCRRIIPPTTIIOONN
       _R_e_s_o_l_v_+  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 _/_e_t_c_/_h_o_s_t_s file, and Sun's Network  Information
       Service (NIS).

       The  programmer interface to the resolv+ routines is iden-
       tical to that of the standard resolver library.  For  fur-
       ther information see the appropriate manual pages.

CCOONNFFIIGGUURRAATTIIOONN
       As   with   the   standard   resolver  library,  the  file
       _/_e_t_c_/_r_e_s_o_l_v_._c_o_n_f must be set up before  the  resolver  can
       function.   In  addition, the file _/_e_t_c_/_h_o_s_t_._c_o_n_f contains
       configuration information specific to resolv+.

       The _h_o_s_t_._c_o_n_f file should contain one  configuration  key-
       word  per  line,  followed  by  appropriate  configuration
       information.  The keywords recognized are _o_r_d_e_r _,  _t_r_i_m  _,
       _m_u_l_t_i _, _n_o_s_p_o_o_f _, and _r_e_o_r_d_e_r _.  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 _b_i_n_d _, _h_o_s_t_s and _n_i_s _.

       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 host-
              names 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  non-qualified,  as  appropriate  for  the local
              installation.)

       multi  Valid values are _o_n and _o_f_f _.  If set to "on,"  the
              resolv+ library will return all valid addresses for
              a host that appears in the _/_e_t_c_/_h_o_s_t_s 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.

       nospoof
              Valid  values are _o_n and _o_f_f _.  If set to "on," the
              resolv+ library will attempt  to  prevent  hostname



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RESOLV+(8)                                             RESOLV+(8)


              spoofing to enhance the security of _r_l_o_g_i_n and _r_s_h.
              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 _n_o_s_p_o_o_f
              option is also set, resolv+ will log a  warning  of
              the  error  via  the  _s_y_s_l_o_g facility.  The default
              value is off.

       reorder
              Valid values are _o_n and _o_f_f  _.   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.

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

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

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

       RESOLV_SPOOF_CHECK
              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.

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

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

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

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



                         August 19, 1992                        2





RESOLV+(8)                                             RESOLV+(8)


FFIILLEESS
       /etc/host.conf, /etc/hosts

BBUUGGSS
       Quite possibly.

AAUUTTHHOORR
       The  original BIND resolver library comes from the Univer-
       sity 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 enhance-
       ments  were contributed by Patrick Gosling, Chris Metcalf,
       John DiMarco and J. Porter Clark, John P.  Rouillard,  Dan
       O'Neill and Tom Limoncelli.

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








































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