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NAME

       host.conf - resolver configuration file

DESCRIPTION

       The  file /etc/host.conf contains configuration information specific to
       the resolver library.  It should contain one configuration keyword  per
       line,  followed by appropriate configuration information.  The keywords
       recognized are order, trim, multi, nospoof, spoof, and reorder.   These
       keywords are described below.

       order  This keyword specifies how host lookups are to be performed.  It
              should be followed by one or more lookup methods,  separated  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 list of domains,  separated  by  colons  (’:’),
              semicolons  (’;’)  or  commas (’,’), 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  ensure  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 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.

       nospoof
              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.  The default value is off.

       spoofalert
              Valid  values  are  on and off.  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.

       spoof  Valid values are off, nowarn and warn.  If this option is set to
              off, spoofed addresses are permitted and  no  warnings  will  be
              emitted via the syslog facility.  If this option is set to warn,
              resolv+ will attempt to prevent hostname spoofing to enhance the
              security and log a warning of the error via the syslog facility.
              If this option is  set  to  nowarn,  the  resolv+  library  will
              attempt to prevent hostname spoofing to enhance the security but
              not emit warnings via the syslog facility.  Setting this  option
              to anything else is equal to setting it to nowarn.

       reorder
              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(3)  is
              performed.  Reordering is done  for  all  lookup  methods.   The
              default value is off.

ENVIRONMENT

       There  are six environment variables that can be used to allow users to
       override the behavior which is configured in /etc/host.conf.

       RESOLV_HOST_CONF
              If set this variable points  to  a  file  that  should  be  read
              instead of /etc/host.conf.

       RESOLV_SERV_ORDER
              Overrides the order command.

       RESOLV_SPOOF_CHECK
              Overrides the nospoof, spoofalert and spoof commands in the same
              way as the spoof command  is  parsed.   Valid  values  are  off,
              nowarn and warn.

       RESOLV_MULTI
              Overrides the multi command.

       RESOLV_REORDER
              Overrides the reorder command.

       RESOLV_ADD_TRIM_DOMAINS
              A  list of domains,  separated by colons (’:’), semicolons (’;’)
              or commas (’,’), with the leading dot, which will  be  added  to
              the list of domains that should be trimmed.

       RESOLV_OVERRIDE_TRIM_DOMAINS
              A  list of domains,  separated by colons (’:’), semicolons (’;’)
              or commas (’,’), with the leading dot, which  will  replace  the
              list  of  domains  that  should  be trimmed.  Overrides the trim
              command.

FILES

       /etc/host.conf
              Resolver configuration file

       /etc/resolv.conf
              Resolver configuration file

       /etc/hosts
              Local hosts database

NOTES

       The   following   differences   exist   compared   to   the    original
       implementation.   A  new  command  spoof and a new environment variable
       RESOLV_SPOOF_CHECK can take arguments like off, nowarn and warn.   Line
       comments can appear anywhere and not only at the beginning of a line.

SEE ALSO

       gethostbyname(3), hostname(7), named(8), resolv+(8)

COLOPHON

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