diff --git a/configure b/configure
index ddaa31dab8..cdf1b82a58 100755
--- a/configure
+++ b/configure
@@ -1,6 +1,6 @@
 #! /bin/sh
 
-# From configure.in Revision: 1.67 
+# From configure.in Revision: 1.69 
 
 
 
@@ -126,6 +126,8 @@ ac_help="$ac_help
   --with-gnu-ld           assume the C compiler uses GNU ld [default=no]"
 ac_help="$ac_help
   --disable-libtool-lock  avoid locking (might break parallel builds)"
+ac_help="$ac_help
+  --enable-ipv6		use IPv6 [default: autodetect]"
 ac_help="$ac_help
   --with-kame[=PATH]	use Kame IPv6 [default path /usr/local/v6]"
 
@@ -666,7 +668,7 @@ else { echo "configure: error: can not run $ac_config_sub" 1>&2; exit 1; }
 fi
 
 echo $ac_n "checking host system type""... $ac_c" 1>&6
-echo "configure:670: checking host system type" >&5
+echo "configure:672: checking host system type" >&5
 
 host_alias=$host
 case "$host_alias" in
@@ -688,7 +690,7 @@ echo "$ac_t""$host" 1>&6
 
 
 echo $ac_n "checking whether ${MAKE-make} sets \${MAKE}""... $ac_c" 1>&6
-echo "configure:692: checking whether ${MAKE-make} sets \${MAKE}" >&5
+echo "configure:694: checking whether ${MAKE-make} sets \${MAKE}" >&5
 set dummy ${MAKE-make}; ac_make=`echo "$2" | sed 'y%./+-%__p_%'`
 if eval "test \"`echo '$''{'ac_cv_prog_make_${ac_make}_set'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
@@ -717,7 +719,7 @@ fi
 # Extract the first word of "ranlib", so it can be a program name with args.
 set dummy ranlib; ac_word=$2
 echo $ac_n "checking for $ac_word""... $ac_c" 1>&6
-echo "configure:721: checking for $ac_word" >&5
+echo "configure:723: checking for $ac_word" >&5
 if eval "test \"`echo '$''{'ac_cv_prog_RANLIB'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
@@ -756,7 +758,7 @@ fi
 # SVR4 /usr/ucb/install, which tries to use the nonexistent group "staff"
 # ./install, which can be erroneously created by make from ./install.sh.
 echo $ac_n "checking for a BSD compatible install""... $ac_c" 1>&6
-echo "configure:760: checking for a BSD compatible install" >&5
+echo "configure:762: checking for a BSD compatible install" >&5
 if test -z "$INSTALL"; then
 if eval "test \"`echo '$''{'ac_cv_path_install'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
@@ -819,7 +821,7 @@ STD_CWARNINGS=""
 # Extract the first word of "ar", so it can be a program name with args.
 set dummy ar; ac_word=$2
 echo $ac_n "checking for $ac_word""... $ac_c" 1>&6
-echo "configure:823: checking for $ac_word" >&5
+echo "configure:825: checking for $ac_word" >&5
 if eval "test \"`echo '$''{'ac_cv_path_AR'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
@@ -892,7 +894,7 @@ case "$host" in
   *-netbsd*)
 	CC="gcc"
 	echo $ac_n "checking which thread library to use""... $ac_c" 1>&6
-echo "configure:896: checking which thread library to use" >&5
+echo "configure:898: checking which thread library to use" >&5
 
 	# Check whether --with-mit-pthreads or --without-mit-pthreads was given.
 if test "${with_mit_pthreads+set}" = set; then
@@ -955,7 +957,7 @@ esac
 # Extract the first word of "gcc", so it can be a program name with args.
 set dummy gcc; ac_word=$2
 echo $ac_n "checking for $ac_word""... $ac_c" 1>&6
-echo "configure:959: checking for $ac_word" >&5
+echo "configure:961: checking for $ac_word" >&5
 if eval "test \"`echo '$''{'ac_cv_prog_CC'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
@@ -985,7 +987,7 @@ if test -z "$CC"; then
   # Extract the first word of "cc", so it can be a program name with args.
 set dummy cc; ac_word=$2
 echo $ac_n "checking for $ac_word""... $ac_c" 1>&6
-echo "configure:989: checking for $ac_word" >&5
+echo "configure:991: checking for $ac_word" >&5
 if eval "test \"`echo '$''{'ac_cv_prog_CC'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
@@ -1036,7 +1038,7 @@ fi
       # Extract the first word of "cl", so it can be a program name with args.
 set dummy cl; ac_word=$2
 echo $ac_n "checking for $ac_word""... $ac_c" 1>&6
-echo "configure:1040: checking for $ac_word" >&5
+echo "configure:1042: checking for $ac_word" >&5
 if eval "test \"`echo '$''{'ac_cv_prog_CC'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
@@ -1068,7 +1070,7 @@ fi
 fi
 
 echo $ac_n "checking whether the C compiler ($CC $CFLAGS $LDFLAGS) works""... $ac_c" 1>&6
-echo "configure:1072: checking whether the C compiler ($CC $CFLAGS $LDFLAGS) works" >&5
+echo "configure:1074: checking whether the C compiler ($CC $CFLAGS $LDFLAGS) works" >&5
 
 ac_ext=c
 # CFLAGS is not in ac_cpp because -g, -O, etc. are not valid cpp options.
@@ -1079,12 +1081,12 @@ cross_compiling=$ac_cv_prog_cc_cross
 
 cat > conftest.$ac_ext << EOF
 
-#line 1083 "configure"
+#line 1085 "configure"
 #include "confdefs.h"
 
 main(){return(0);}
 EOF
-if { (eval echo configure:1088: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest${ac_exeext}; then
+if { (eval echo configure:1090: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest${ac_exeext}; then
   ac_cv_prog_cc_works=yes
   # If we can't run a trivial program, we are probably using a cross compiler.
   if (./conftest; exit) 2>/dev/null; then
@@ -1110,12 +1112,12 @@ if test $ac_cv_prog_cc_works = no; then
   { echo "configure: error: installation or configuration problem: C compiler cannot create executables." 1>&2; exit 1; }
 fi
 echo $ac_n "checking whether the C compiler ($CC $CFLAGS $LDFLAGS) is a cross-compiler""... $ac_c" 1>&6
-echo "configure:1114: checking whether the C compiler ($CC $CFLAGS $LDFLAGS) is a cross-compiler" >&5
+echo "configure:1116: checking whether the C compiler ($CC $CFLAGS $LDFLAGS) is a cross-compiler" >&5
 echo "$ac_t""$ac_cv_prog_cc_cross" 1>&6
 cross_compiling=$ac_cv_prog_cc_cross
 
 echo $ac_n "checking whether we are using GNU C""... $ac_c" 1>&6
-echo "configure:1119: checking whether we are using GNU C" >&5
+echo "configure:1121: checking whether we are using GNU C" >&5
 if eval "test \"`echo '$''{'ac_cv_prog_gcc'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
@@ -1124,7 +1126,7 @@ else
   yes;
 #endif
 EOF
-if { ac_try='${CC-cc} -E conftest.c'; { (eval echo configure:1128: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }; } | egrep yes >/dev/null 2>&1; then
+if { ac_try='${CC-cc} -E conftest.c'; { (eval echo configure:1130: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }; } | egrep yes >/dev/null 2>&1; then
   ac_cv_prog_gcc=yes
 else
   ac_cv_prog_gcc=no
@@ -1143,7 +1145,7 @@ ac_test_CFLAGS="${CFLAGS+set}"
 ac_save_CFLAGS="$CFLAGS"
 CFLAGS=
 echo $ac_n "checking whether ${CC-cc} accepts -g""... $ac_c" 1>&6
-echo "configure:1147: checking whether ${CC-cc} accepts -g" >&5
+echo "configure:1149: checking whether ${CC-cc} accepts -g" >&5
 if eval "test \"`echo '$''{'ac_cv_prog_cc_g'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
@@ -1179,7 +1181,7 @@ do
 # Extract the first word of "$ac_prog", so it can be a program name with args.
 set dummy $ac_prog; ac_word=$2
 echo $ac_n "checking for $ac_word""... $ac_c" 1>&6
-echo "configure:1183: checking for $ac_word" >&5
+echo "configure:1185: checking for $ac_word" >&5
 if eval "test \"`echo '$''{'ac_cv_prog_YACC'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
@@ -1211,7 +1213,7 @@ test -n "$YACC" || YACC="yacc"
 
 
 echo $ac_n "checking how to run the C preprocessor""... $ac_c" 1>&6
-echo "configure:1215: checking how to run the C preprocessor" >&5
+echo "configure:1217: checking how to run the C preprocessor" >&5
 # On Suns, sometimes $CPP names a directory.
 if test -n "$CPP" && test -d "$CPP"; then
   CPP=
@@ -1226,13 +1228,13 @@ else
   # On the NeXT, cc -E runs the code through the compiler's parser,
   # not just through cpp.
   cat > conftest.$ac_ext <<EOF
-#line 1230 "configure"
+#line 1232 "configure"
 #include "confdefs.h"
 #include <assert.h>
 Syntax Error
 EOF
 ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
-{ (eval echo configure:1236: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
+{ (eval echo configure:1238: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
 ac_err=`grep -v '^ *+' conftest.out | grep -v "^conftest.${ac_ext}\$"`
 if test -z "$ac_err"; then
   :
@@ -1243,13 +1245,13 @@ else
   rm -rf conftest*
   CPP="${CC-cc} -E -traditional-cpp"
   cat > conftest.$ac_ext <<EOF
-#line 1247 "configure"
+#line 1249 "configure"
 #include "confdefs.h"
 #include <assert.h>
 Syntax Error
 EOF
 ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
-{ (eval echo configure:1253: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
+{ (eval echo configure:1255: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
 ac_err=`grep -v '^ *+' conftest.out | grep -v "^conftest.${ac_ext}\$"`
 if test -z "$ac_err"; then
   :
@@ -1260,13 +1262,13 @@ else
   rm -rf conftest*
   CPP="${CC-cc} -nologo -E"
   cat > conftest.$ac_ext <<EOF
-#line 1264 "configure"
+#line 1266 "configure"
 #include "confdefs.h"
 #include <assert.h>
 Syntax Error
 EOF
 ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
-{ (eval echo configure:1270: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
+{ (eval echo configure:1272: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
 ac_err=`grep -v '^ *+' conftest.out | grep -v "^conftest.${ac_ext}\$"`
 if test -z "$ac_err"; then
   :
@@ -1291,12 +1293,12 @@ fi
 echo "$ac_t""$CPP" 1>&6
 
 echo $ac_n "checking for ANSI C header files""... $ac_c" 1>&6
-echo "configure:1295: checking for ANSI C header files" >&5
+echo "configure:1297: checking for ANSI C header files" >&5
 if eval "test \"`echo '$''{'ac_cv_header_stdc'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 1300 "configure"
+#line 1302 "configure"
 #include "confdefs.h"
 #include <stdlib.h>
 #include <stdarg.h>
@@ -1304,7 +1306,7 @@ else
 #include <float.h>
 EOF
 ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
-{ (eval echo configure:1308: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
+{ (eval echo configure:1310: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
 ac_err=`grep -v '^ *+' conftest.out | grep -v "^conftest.${ac_ext}\$"`
 if test -z "$ac_err"; then
   rm -rf conftest*
@@ -1321,7 +1323,7 @@ rm -f conftest*
 if test $ac_cv_header_stdc = yes; then
   # SunOS 4.x string.h does not declare mem*, contrary to ANSI.
 cat > conftest.$ac_ext <<EOF
-#line 1325 "configure"
+#line 1327 "configure"
 #include "confdefs.h"
 #include <string.h>
 EOF
@@ -1339,7 +1341,7 @@ fi
 if test $ac_cv_header_stdc = yes; then
   # ISC 2.0.2 stdlib.h does not declare free, contrary to ANSI.
 cat > conftest.$ac_ext <<EOF
-#line 1343 "configure"
+#line 1345 "configure"
 #include "confdefs.h"
 #include <stdlib.h>
 EOF
@@ -1360,7 +1362,7 @@ if test "$cross_compiling" = yes; then
   :
 else
   cat > conftest.$ac_ext <<EOF
-#line 1364 "configure"
+#line 1366 "configure"
 #include "confdefs.h"
 #include <ctype.h>
 #define ISLOWER(c) ('a' <= (c) && (c) <= 'z')
@@ -1371,7 +1373,7 @@ if (XOR (islower (i), ISLOWER (i)) || toupper (i) != TOUPPER (i)) exit(2);
 exit (0); }
 
 EOF
-if { (eval echo configure:1375: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest${ac_exeext} && (./conftest; exit) 2>/dev/null
+if { (eval echo configure:1377: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest${ac_exeext} && (./conftest; exit) 2>/dev/null
 then
   :
 else
@@ -1394,21 +1396,21 @@ EOF
 
 fi
 
-for ac_hdr in fcntl.h sys/time.h unistd.h sys/sockio.h
+for ac_hdr in fcntl.h sys/time.h unistd.h sys/sockio.h netinet6/in6.h
 do
 ac_safe=`echo "$ac_hdr" | sed 'y%./+-%__p_%'`
 echo $ac_n "checking for $ac_hdr""... $ac_c" 1>&6
-echo "configure:1402: checking for $ac_hdr" >&5
+echo "configure:1404: checking for $ac_hdr" >&5
 if eval "test \"`echo '$''{'ac_cv_header_$ac_safe'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 1407 "configure"
+#line 1409 "configure"
 #include "confdefs.h"
 #include <$ac_hdr>
 EOF
 ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
-{ (eval echo configure:1412: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
+{ (eval echo configure:1414: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
 ac_err=`grep -v '^ *+' conftest.out | grep -v "^conftest.${ac_ext}\$"`
 if test -z "$ac_err"; then
   rm -rf conftest*
@@ -1436,12 +1438,12 @@ done
 
 
 echo $ac_n "checking for working const""... $ac_c" 1>&6
-echo "configure:1440: checking for working const" >&5
+echo "configure:1442: checking for working const" >&5
 if eval "test \"`echo '$''{'ac_cv_c_const'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 1445 "configure"
+#line 1447 "configure"
 #include "confdefs.h"
 
 int main() {
@@ -1490,7 +1492,7 @@ ccp = (char const *const *) p;
 
 ; return 0; }
 EOF
-if { (eval echo configure:1494: \"$ac_compile\") 1>&5; (eval $ac_compile) 2>&5; }; then
+if { (eval echo configure:1496: \"$ac_compile\") 1>&5; (eval $ac_compile) 2>&5; }; then
   rm -rf conftest*
   ac_cv_c_const=yes
 else
@@ -1511,21 +1513,21 @@ EOF
 fi
 
 echo $ac_n "checking for inline""... $ac_c" 1>&6
-echo "configure:1515: checking for inline" >&5
+echo "configure:1517: checking for inline" >&5
 if eval "test \"`echo '$''{'ac_cv_c_inline'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   ac_cv_c_inline=no
 for ac_kw in inline __inline__ __inline; do
   cat > conftest.$ac_ext <<EOF
-#line 1522 "configure"
+#line 1524 "configure"
 #include "confdefs.h"
 
 int main() {
 } $ac_kw foo() {
 ; return 0; }
 EOF
-if { (eval echo configure:1529: \"$ac_compile\") 1>&5; (eval $ac_compile) 2>&5; }; then
+if { (eval echo configure:1531: \"$ac_compile\") 1>&5; (eval $ac_compile) 2>&5; }; then
   rm -rf conftest*
   ac_cv_c_inline=$ac_kw; break
 else
@@ -1551,12 +1553,12 @@ EOF
 esac
 
 echo $ac_n "checking for size_t""... $ac_c" 1>&6
-echo "configure:1555: checking for size_t" >&5
+echo "configure:1557: checking for size_t" >&5
 if eval "test \"`echo '$''{'ac_cv_type_size_t'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 1560 "configure"
+#line 1562 "configure"
 #include "confdefs.h"
 #include <sys/types.h>
 #if STDC_HEADERS
@@ -1584,12 +1586,12 @@ EOF
 fi
 
 echo $ac_n "checking whether time.h and sys/time.h may both be included""... $ac_c" 1>&6
-echo "configure:1588: checking whether time.h and sys/time.h may both be included" >&5
+echo "configure:1590: checking whether time.h and sys/time.h may both be included" >&5
 if eval "test \"`echo '$''{'ac_cv_header_time'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 1593 "configure"
+#line 1595 "configure"
 #include "confdefs.h"
 #include <sys/types.h>
 #include <sys/time.h>
@@ -1598,7 +1600,7 @@ int main() {
 struct tm *tp;
 ; return 0; }
 EOF
-if { (eval echo configure:1602: \"$ac_compile\") 1>&5; (eval $ac_compile) 2>&5; }; then
+if { (eval echo configure:1604: \"$ac_compile\") 1>&5; (eval $ac_compile) 2>&5; }; then
   rm -rf conftest*
   ac_cv_header_time=yes
 else
@@ -1620,7 +1622,7 @@ fi
 
 
 echo $ac_n "checking for pthread_create in -lpthread""... $ac_c" 1>&6
-echo "configure:1624: checking for pthread_create in -lpthread" >&5
+echo "configure:1626: checking for pthread_create in -lpthread" >&5
 ac_lib_var=`echo pthread'_'pthread_create | sed 'y%./+-%__p_%'`
 if eval "test \"`echo '$''{'ac_cv_lib_$ac_lib_var'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
@@ -1628,7 +1630,7 @@ else
   ac_save_LIBS="$LIBS"
 LIBS="-lpthread  $LIBS"
 cat > conftest.$ac_ext <<EOF
-#line 1632 "configure"
+#line 1634 "configure"
 #include "confdefs.h"
 /* Override any gcc2 internal prototype to avoid an error.  */
 /* We use char because int might match the return type of a gcc2
@@ -1639,7 +1641,7 @@ int main() {
 pthread_create()
 ; return 0; }
 EOF
-if { (eval echo configure:1643: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest${ac_exeext}; then
+if { (eval echo configure:1645: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest${ac_exeext}; then
   rm -rf conftest*
   eval "ac_cv_lib_$ac_lib_var=yes"
 else
@@ -1665,7 +1667,7 @@ EOF
 else
   echo "$ac_t""no" 1>&6
 echo $ac_n "checking for __pthread_create in -lpthread""... $ac_c" 1>&6
-echo "configure:1669: checking for __pthread_create in -lpthread" >&5
+echo "configure:1671: checking for __pthread_create in -lpthread" >&5
 ac_lib_var=`echo pthread'_'__pthread_create | sed 'y%./+-%__p_%'`
 if eval "test \"`echo '$''{'ac_cv_lib_$ac_lib_var'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
@@ -1673,7 +1675,7 @@ else
   ac_save_LIBS="$LIBS"
 LIBS="-lpthread  $LIBS"
 cat > conftest.$ac_ext <<EOF
-#line 1677 "configure"
+#line 1679 "configure"
 #include "confdefs.h"
 /* Override any gcc2 internal prototype to avoid an error.  */
 /* We use char because int might match the return type of a gcc2
@@ -1684,7 +1686,7 @@ int main() {
 __pthread_create()
 ; return 0; }
 EOF
-if { (eval echo configure:1688: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest${ac_exeext}; then
+if { (eval echo configure:1690: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest${ac_exeext}; then
   rm -rf conftest*
   eval "ac_cv_lib_$ac_lib_var=yes"
 else
@@ -1712,7 +1714,7 @@ else
 fi
 
              echo $ac_n "checking for __pthread_create_system in -lpthread""... $ac_c" 1>&6
-echo "configure:1716: checking for __pthread_create_system in -lpthread" >&5
+echo "configure:1718: checking for __pthread_create_system in -lpthread" >&5
 ac_lib_var=`echo pthread'_'__pthread_create_system | sed 'y%./+-%__p_%'`
 if eval "test \"`echo '$''{'ac_cv_lib_$ac_lib_var'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
@@ -1720,7 +1722,7 @@ else
   ac_save_LIBS="$LIBS"
 LIBS="-lpthread  $LIBS"
 cat > conftest.$ac_ext <<EOF
-#line 1724 "configure"
+#line 1726 "configure"
 #include "confdefs.h"
 /* Override any gcc2 internal prototype to avoid an error.  */
 /* We use char because int might match the return type of a gcc2
@@ -1731,7 +1733,7 @@ int main() {
 __pthread_create_system()
 ; return 0; }
 EOF
-if { (eval echo configure:1735: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest${ac_exeext}; then
+if { (eval echo configure:1737: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest${ac_exeext}; then
   rm -rf conftest*
   eval "ac_cv_lib_$ac_lib_var=yes"
 else
@@ -1765,7 +1767,7 @@ fi
 
 if test "$ac_cv_lib_pthread" != "yes"; then
 	echo $ac_n "checking for pthread_create in -lc_r""... $ac_c" 1>&6
-echo "configure:1769: checking for pthread_create in -lc_r" >&5
+echo "configure:1771: checking for pthread_create in -lc_r" >&5
 ac_lib_var=`echo c_r'_'pthread_create | sed 'y%./+-%__p_%'`
 if eval "test \"`echo '$''{'ac_cv_lib_$ac_lib_var'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
@@ -1773,7 +1775,7 @@ else
   ac_save_LIBS="$LIBS"
 LIBS="-lc_r  $LIBS"
 cat > conftest.$ac_ext <<EOF
-#line 1777 "configure"
+#line 1779 "configure"
 #include "confdefs.h"
 /* Override any gcc2 internal prototype to avoid an error.  */
 /* We use char because int might match the return type of a gcc2
@@ -1784,7 +1786,7 @@ int main() {
 pthread_create()
 ; return 0; }
 EOF
-if { (eval echo configure:1788: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest${ac_exeext}; then
+if { (eval echo configure:1790: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest${ac_exeext}; then
   rm -rf conftest*
   eval "ac_cv_lib_$ac_lib_var=yes"
 else
@@ -1815,7 +1817,7 @@ fi
 
 
 echo $ac_n "checking for sigwait in -lpthread""... $ac_c" 1>&6
-echo "configure:1819: checking for sigwait in -lpthread" >&5
+echo "configure:1821: checking for sigwait in -lpthread" >&5
 ac_lib_var=`echo pthread'_'sigwait | sed 'y%./+-%__p_%'`
 if eval "test \"`echo '$''{'ac_cv_lib_$ac_lib_var'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
@@ -1823,7 +1825,7 @@ else
   ac_save_LIBS="$LIBS"
 LIBS="-lpthread  $LIBS"
 cat > conftest.$ac_ext <<EOF
-#line 1827 "configure"
+#line 1829 "configure"
 #include "confdefs.h"
 /* Override any gcc2 internal prototype to avoid an error.  */
 /* We use char because int might match the return type of a gcc2
@@ -1834,7 +1836,7 @@ int main() {
 sigwait()
 ; return 0; }
 EOF
-if { (eval echo configure:1838: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest${ac_exeext}; then
+if { (eval echo configure:1840: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest${ac_exeext}; then
   rm -rf conftest*
   eval "ac_cv_lib_$ac_lib_var=yes"
 else
@@ -1856,7 +1858,7 @@ EOF
 else
   echo "$ac_t""no" 1>&6
 echo $ac_n "checking for _Psigwait in -lpthread""... $ac_c" 1>&6
-echo "configure:1860: checking for _Psigwait in -lpthread" >&5
+echo "configure:1862: checking for _Psigwait in -lpthread" >&5
 ac_lib_var=`echo pthread'_'_Psigwait | sed 'y%./+-%__p_%'`
 if eval "test \"`echo '$''{'ac_cv_lib_$ac_lib_var'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
@@ -1864,7 +1866,7 @@ else
   ac_save_LIBS="$LIBS"
 LIBS="-lpthread  $LIBS"
 cat > conftest.$ac_ext <<EOF
-#line 1868 "configure"
+#line 1870 "configure"
 #include "confdefs.h"
 /* Override any gcc2 internal prototype to avoid an error.  */
 /* We use char because int might match the return type of a gcc2
@@ -1875,7 +1877,7 @@ int main() {
 _Psigwait()
 ; return 0; }
 EOF
-if { (eval echo configure:1879: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest${ac_exeext}; then
+if { (eval echo configure:1881: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest${ac_exeext}; then
   rm -rf conftest*
   eval "ac_cv_lib_$ac_lib_var=yes"
 else
@@ -1912,12 +1914,12 @@ EOF
 esac
 
 echo $ac_n "checking for catgets""... $ac_c" 1>&6
-echo "configure:1916: checking for catgets" >&5
+echo "configure:1918: checking for catgets" >&5
 if eval "test \"`echo '$''{'ac_cv_func_catgets'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 1921 "configure"
+#line 1923 "configure"
 #include "confdefs.h"
 /* System header to define __stub macros and hopefully few prototypes,
     which can conflict with char catgets(); below.  */
@@ -1940,7 +1942,7 @@ catgets();
 
 ; return 0; }
 EOF
-if { (eval echo configure:1944: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest${ac_exeext}; then
+if { (eval echo configure:1946: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest${ac_exeext}; then
   rm -rf conftest*
   eval "ac_cv_func_catgets=yes"
 else
@@ -1984,7 +1986,7 @@ case "$host" in
 		;;
 	*)
 		echo $ac_n "checking for socket in -lsocket""... $ac_c" 1>&6
-echo "configure:1988: checking for socket in -lsocket" >&5
+echo "configure:1990: checking for socket in -lsocket" >&5
 ac_lib_var=`echo socket'_'socket | sed 'y%./+-%__p_%'`
 if eval "test \"`echo '$''{'ac_cv_lib_$ac_lib_var'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
@@ -1992,7 +1994,7 @@ else
   ac_save_LIBS="$LIBS"
 LIBS="-lsocket  $LIBS"
 cat > conftest.$ac_ext <<EOF
-#line 1996 "configure"
+#line 1998 "configure"
 #include "confdefs.h"
 /* Override any gcc2 internal prototype to avoid an error.  */
 /* We use char because int might match the return type of a gcc2
@@ -2003,7 +2005,7 @@ int main() {
 socket()
 ; return 0; }
 EOF
-if { (eval echo configure:2007: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest${ac_exeext}; then
+if { (eval echo configure:2009: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest${ac_exeext}; then
   rm -rf conftest*
   eval "ac_cv_lib_$ac_lib_var=yes"
 else
@@ -2031,7 +2033,7 @@ else
 fi
 
 		echo $ac_n "checking for inet_ntoa in -lnsl""... $ac_c" 1>&6
-echo "configure:2035: checking for inet_ntoa in -lnsl" >&5
+echo "configure:2037: checking for inet_ntoa in -lnsl" >&5
 ac_lib_var=`echo nsl'_'inet_ntoa | sed 'y%./+-%__p_%'`
 if eval "test \"`echo '$''{'ac_cv_lib_$ac_lib_var'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
@@ -2039,7 +2041,7 @@ else
   ac_save_LIBS="$LIBS"
 LIBS="-lnsl  $LIBS"
 cat > conftest.$ac_ext <<EOF
-#line 2043 "configure"
+#line 2045 "configure"
 #include "confdefs.h"
 /* Override any gcc2 internal prototype to avoid an error.  */
 /* We use char because int might match the return type of a gcc2
@@ -2050,7 +2052,7 @@ int main() {
 inet_ntoa()
 ; return 0; }
 EOF
-if { (eval echo configure:2054: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest${ac_exeext}; then
+if { (eval echo configure:2056: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest${ac_exeext}; then
   rm -rf conftest*
   eval "ac_cv_lib_$ac_lib_var=yes"
 else
@@ -2121,9 +2123,9 @@ esac
 
 
 echo $ac_n "checking for sa_len in struct sockaddr""... $ac_c" 1>&6
-echo "configure:2125: checking for sa_len in struct sockaddr" >&5
+echo "configure:2127: checking for sa_len in struct sockaddr" >&5
 cat > conftest.$ac_ext <<EOF
-#line 2127 "configure"
+#line 2129 "configure"
 #include "confdefs.h"
 
 #include <sys/types.h>
@@ -2132,7 +2134,7 @@ int main() {
 struct sockaddr sa; sa.sa_len = 0; return (0);
 ; return 0; }
 EOF
-if { (eval echo configure:2136: \"$ac_compile\") 1>&5; (eval $ac_compile) 2>&5; }; then
+if { (eval echo configure:2138: \"$ac_compile\") 1>&5; (eval $ac_compile) 2>&5; }; then
   rm -rf conftest*
   echo "$ac_t""yes" 1>&6
 	ISC_PLATFORM_HAVESALEN="#define ISC_PLATFORM_HAVESALEN 1"
@@ -2148,9 +2150,9 @@ rm -f conftest*
 
 
 echo $ac_n "checking for struct msghdr flavor""... $ac_c" 1>&6
-echo "configure:2152: checking for struct msghdr flavor" >&5
+echo "configure:2154: checking for struct msghdr flavor" >&5
 cat > conftest.$ac_ext <<EOF
-#line 2154 "configure"
+#line 2156 "configure"
 #include "confdefs.h"
 
 #include <sys/types.h>
@@ -2159,7 +2161,7 @@ int main() {
 struct msghdr msg; msg.msg_flags = 0; return (0);
 ; return 0; }
 EOF
-if { (eval echo configure:2163: \"$ac_compile\") 1>&5; (eval $ac_compile) 2>&5; }; then
+if { (eval echo configure:2165: \"$ac_compile\") 1>&5; (eval $ac_compile) 2>&5; }; then
   rm -rf conftest*
   echo "$ac_t""4.4BSD" 1>&6
 	ISC_PLATFORM_MSGHDRFLAVOR="#define ISC_NET_BSD44MSGHDR 1"
@@ -2174,9 +2176,9 @@ rm -f conftest*
 
 
 echo $ac_n "checking for type in_port_t""... $ac_c" 1>&6
-echo "configure:2178: checking for type in_port_t" >&5
+echo "configure:2180: checking for type in_port_t" >&5
 cat > conftest.$ac_ext <<EOF
-#line 2180 "configure"
+#line 2182 "configure"
 #include "confdefs.h"
 
 #include <sys/types.h>
@@ -2185,7 +2187,7 @@ int main() {
 in_port_t port = 25; return (0);
 ; return 0; }
 EOF
-if { (eval echo configure:2189: \"$ac_compile\") 1>&5; (eval $ac_compile) 2>&5; }; then
+if { (eval echo configure:2191: \"$ac_compile\") 1>&5; (eval $ac_compile) 2>&5; }; then
   rm -rf conftest*
   echo "$ac_t""yes" 1>&6
 	ISC_PLATFORM_NEEDPORTT="#undef ISC_PLATFORM_NEEDPORTT"
@@ -2201,9 +2203,9 @@ rm -f conftest*
 
 
 echo $ac_n "checking for interface list sysctl""... $ac_c" 1>&6
-echo "configure:2205: checking for interface list sysctl" >&5
+echo "configure:2207: checking for interface list sysctl" >&5
 cat > conftest.$ac_ext <<EOF
-#line 2207 "configure"
+#line 2209 "configure"
 #include "confdefs.h"
 
 #include <sys/param.h>
@@ -2310,7 +2312,7 @@ else
 fi
 
 echo $ac_n "checking build system type""... $ac_c" 1>&6
-echo "configure:2314: checking build system type" >&5
+echo "configure:2316: checking build system type" >&5
 
 build_alias=$build
 case "$build_alias" in
@@ -2339,7 +2341,7 @@ ac_prog=ld
 if test "$ac_cv_prog_gcc" = yes; then
   # Check if gcc -print-prog-name=ld gives a path.
   echo $ac_n "checking for ld used by GCC""... $ac_c" 1>&6
-echo "configure:2343: checking for ld used by GCC" >&5
+echo "configure:2345: checking for ld used by GCC" >&5
   ac_prog=`($CC -print-prog-name=ld) 2>&5`
   case "$ac_prog" in
     # Accept absolute paths.
@@ -2363,10 +2365,10 @@ echo "configure:2343: checking for ld used by GCC" >&5
   esac
 elif test "$with_gnu_ld" = yes; then
   echo $ac_n "checking for GNU ld""... $ac_c" 1>&6
-echo "configure:2367: checking for GNU ld" >&5
+echo "configure:2369: checking for GNU ld" >&5
 else
   echo $ac_n "checking for non-GNU ld""... $ac_c" 1>&6
-echo "configure:2370: checking for non-GNU ld" >&5
+echo "configure:2372: checking for non-GNU ld" >&5
 fi
 if eval "test \"`echo '$''{'ac_cv_path_LD'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
@@ -2402,7 +2404,7 @@ fi
 test -z "$LD" && { echo "configure: error: no acceptable ld found in \$PATH" 1>&2; exit 1; }
 
 echo $ac_n "checking if the linker ($LD) is GNU ld""... $ac_c" 1>&6
-echo "configure:2406: checking if the linker ($LD) is GNU ld" >&5
+echo "configure:2408: checking if the linker ($LD) is GNU ld" >&5
 if eval "test \"`echo '$''{'ac_cv_prog_gnu_ld'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
@@ -2418,7 +2420,7 @@ echo "$ac_t""$ac_cv_prog_gnu_ld" 1>&6
 
 
 echo $ac_n "checking for BSD-compatible nm""... $ac_c" 1>&6
-echo "configure:2422: checking for BSD-compatible nm" >&5
+echo "configure:2424: checking for BSD-compatible nm" >&5
 if eval "test \"`echo '$''{'ac_cv_path_NM'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
@@ -2455,7 +2457,7 @@ echo "$ac_t""$NM" 1>&6
 
 
 echo $ac_n "checking whether ln -s works""... $ac_c" 1>&6
-echo "configure:2459: checking whether ln -s works" >&5
+echo "configure:2461: checking whether ln -s works" >&5
 if eval "test \"`echo '$''{'ac_cv_prog_LN_S'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
@@ -2499,8 +2501,8 @@ test x"$silent" = xyes && libtool_flags="$libtool_flags --silent"
 case "$host" in
 *-*-irix6*)
   # Find out which ABI we are using.
-  echo '#line 2503 "configure"' > conftest.$ac_ext
-  if { (eval echo configure:2504: \"$ac_compile\") 1>&5; (eval $ac_compile) 2>&5; }; then
+  echo '#line 2505 "configure"' > conftest.$ac_ext
+  if { (eval echo configure:2506: \"$ac_compile\") 1>&5; (eval $ac_compile) 2>&5; }; then
     case "`/usr/bin/file conftest.o`" in
     *32-bit*)
       LD="${LD-ld} -32"
@@ -2521,19 +2523,19 @@ case "$host" in
   SAVE_CFLAGS="$CFLAGS"
   CFLAGS="$CFLAGS -belf"
   echo $ac_n "checking whether the C compiler needs -belf""... $ac_c" 1>&6
-echo "configure:2525: checking whether the C compiler needs -belf" >&5
+echo "configure:2527: checking whether the C compiler needs -belf" >&5
 if eval "test \"`echo '$''{'lt_cv_cc_needs_belf'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 2530 "configure"
+#line 2532 "configure"
 #include "confdefs.h"
 
 int main() {
 
 ; return 0; }
 EOF
-if { (eval echo configure:2537: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest${ac_exeext}; then
+if { (eval echo configure:2539: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest${ac_exeext}; then
   rm -rf conftest*
   lt_cv_cc_needs_belf=yes
 else
@@ -2647,35 +2649,59 @@ esac
 
 
 
-echo $ac_n "checking for IPv6 structures""... $ac_c" 1>&6
-echo "configure:2652: checking for IPv6 structures" >&5
-cat > conftest.$ac_ext <<EOF
-#line 2654 "configure"
+# Check whether --enable-ipv6 or --disable-ipv6 was given.
+if test "${enable_ipv6+set}" = set; then
+  enableval="$enable_ipv6"
+  :
+fi
+
+
+case "$enable_ipv6" in
+	yes|'')
+		echo $ac_n "checking for IPv6 structures""... $ac_c" 1>&6
+echo "configure:2663: checking for IPv6 structures" >&5
+		cat > conftest.$ac_ext <<EOF
+#line 2665 "configure"
 #include "confdefs.h"
 
-#include <sys/types.h>
-#include <sys/socket.h>
-#include <netinet/in.h>
+		#include <sys/types.h>
+		#include <sys/socket.h>
+		#include <netinet/in.h>
 int main() {
 struct sockaddr_in6 sin6; return (0);
 ; return 0; }
 EOF
-if { (eval echo configure:2664: \"$ac_compile\") 1>&5; (eval $ac_compile) 2>&5; }; then
+if { (eval echo configure:2675: \"$ac_compile\") 1>&5; (eval $ac_compile) 2>&5; }; then
   rm -rf conftest*
   echo "$ac_t""yes" 1>&6
-	ISC_PLATFORM_HAVEIPV6="#define ISC_PLATFORM_HAVEIPV6 1"
+			 found_ipv6=yes
 else
   echo "configure: failed program was:" >&5
   cat conftest.$ac_ext >&5
   rm -rf conftest*
   echo "$ac_t""no" 1>&6
-	ISC_PLATFORM_HAVEIPV6="#undef ISC_PLATFORM_HAVEIPV6"
-	ISC_IPV6_H="ipv6.h"
-	ISC_IPV6_O="ipv6.$O"
-	ISC_ISCIPV6_O="unix/ipv6.$O"
-	ISC_IPV6_C="ipv6.c"
+			 found_ipv6=no
 fi
 rm -f conftest*
+		;;
+	no)
+		found_ipv6=no
+		;;
+esac
+
+case "$found_ipv6" in
+	yes)
+		ISC_PLATFORM_HAVEIPV6="#define ISC_PLATFORM_HAVEIPV6 1",
+		;;
+	no)
+		ISC_PLATFORM_HAVEIPV6="#undef ISC_PLATFORM_HAVEIPV6"
+		ISC_IPV6_H="ipv6.h"
+		ISC_IPV6_O="ipv6.$O"
+		ISC_ISCIPV6_O="unix/ipv6.$O"
+		ISC_IPV6_C="ipv6.c"
+		;;
+esac
+
 
 
 
@@ -2683,7 +2709,7 @@ rm -f conftest*
 
 
 echo $ac_n "checking for Kame IPv6 support""... $ac_c" 1>&6
-echo "configure:2687: checking for Kame IPv6 support" >&5
+echo "configure:2713: checking for Kame IPv6 support" >&5
 # Check whether --with-kame or --without-kame was given.
 if test "${with_kame+set}" = set; then
   withval="$with_kame"
@@ -2706,6 +2732,7 @@ esac
 
 case "$use_kame" in
 	no)
+		echo "$ac_t""no" 1>&6
 		;;
 	*)
 		if test -f $kame_path/lib/libinet6.a; then
@@ -2724,12 +2751,12 @@ esac
 
 
 echo $ac_n "checking for inet_ntop""... $ac_c" 1>&6
-echo "configure:2728: checking for inet_ntop" >&5
+echo "configure:2755: checking for inet_ntop" >&5
 if eval "test \"`echo '$''{'ac_cv_func_inet_ntop'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 2733 "configure"
+#line 2760 "configure"
 #include "confdefs.h"
 /* System header to define __stub macros and hopefully few prototypes,
     which can conflict with char inet_ntop(); below.  */
@@ -2752,7 +2779,7 @@ inet_ntop();
 
 ; return 0; }
 EOF
-if { (eval echo configure:2756: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest${ac_exeext}; then
+if { (eval echo configure:2783: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest${ac_exeext}; then
   rm -rf conftest*
   eval "ac_cv_func_inet_ntop=yes"
 else
@@ -2776,12 +2803,12 @@ ISC_EXTRA_OBJS="$ISC_EXTRA_OBJS inet_ntop.$O"
 fi
 
 echo $ac_n "checking for inet_pton""... $ac_c" 1>&6
-echo "configure:2780: checking for inet_pton" >&5
+echo "configure:2807: checking for inet_pton" >&5
 if eval "test \"`echo '$''{'ac_cv_func_inet_pton'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 2785 "configure"
+#line 2812 "configure"
 #include "confdefs.h"
 /* System header to define __stub macros and hopefully few prototypes,
     which can conflict with char inet_pton(); below.  */
@@ -2804,7 +2831,7 @@ inet_pton();
 
 ; return 0; }
 EOF
-if { (eval echo configure:2808: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest${ac_exeext}; then
+if { (eval echo configure:2835: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest${ac_exeext}; then
   rm -rf conftest*
   eval "ac_cv_func_inet_pton=yes"
 else
@@ -2828,12 +2855,12 @@ ISC_EXTRA_OBJS="$ISC_EXTRA_OBJS inet_pton.$O"
 fi
 
 echo $ac_n "checking for inet_aton""... $ac_c" 1>&6
-echo "configure:2832: checking for inet_aton" >&5
+echo "configure:2859: checking for inet_aton" >&5
 if eval "test \"`echo '$''{'ac_cv_func_inet_aton'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 2837 "configure"
+#line 2864 "configure"
 #include "confdefs.h"
 /* System header to define __stub macros and hopefully few prototypes,
     which can conflict with char inet_aton(); below.  */
@@ -2856,7 +2883,7 @@ inet_aton();
 
 ; return 0; }
 EOF
-if { (eval echo configure:2860: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest${ac_exeext}; then
+if { (eval echo configure:2887: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest${ac_exeext}; then
   rm -rf conftest*
   eval "ac_cv_func_inet_aton=yes"
 else
@@ -2880,12 +2907,12 @@ ISC_EXTRA_OBJS="$ISC_EXTRA_OBJS inet_aton.$O"
 fi
 
 echo $ac_n "checking for vsnprintf""... $ac_c" 1>&6
-echo "configure:2884: checking for vsnprintf" >&5
+echo "configure:2911: checking for vsnprintf" >&5
 if eval "test \"`echo '$''{'ac_cv_func_vsnprintf'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 2889 "configure"
+#line 2916 "configure"
 #include "confdefs.h"
 /* System header to define __stub macros and hopefully few prototypes,
     which can conflict with char vsnprintf(); below.  */
@@ -2908,7 +2935,7 @@ vsnprintf();
 
 ; return 0; }
 EOF
-if { (eval echo configure:2912: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest${ac_exeext}; then
+if { (eval echo configure:2939: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest${ac_exeext}; then
   rm -rf conftest*
   eval "ac_cv_func_vsnprintf=yes"
 else
@@ -2940,12 +2967,12 @@ fi
 
 
 echo $ac_n "checking for chroot""... $ac_c" 1>&6
-echo "configure:2944: checking for chroot" >&5
+echo "configure:2971: checking for chroot" >&5
 if eval "test \"`echo '$''{'ac_cv_func_chroot'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 2949 "configure"
+#line 2976 "configure"
 #include "confdefs.h"
 /* System header to define __stub macros and hopefully few prototypes,
     which can conflict with char chroot(); below.  */
@@ -2968,7 +2995,7 @@ chroot();
 
 ; return 0; }
 EOF
-if { (eval echo configure:2972: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest${ac_exeext}; then
+if { (eval echo configure:2999: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest${ac_exeext}; then
   rm -rf conftest*
   eval "ac_cv_func_chroot=yes"
 else
@@ -2994,17 +3021,17 @@ for ac_hdr in linux/capability.h
 do
 ac_safe=`echo "$ac_hdr" | sed 'y%./+-%__p_%'`
 echo $ac_n "checking for $ac_hdr""... $ac_c" 1>&6
-echo "configure:2998: checking for $ac_hdr" >&5
+echo "configure:3025: checking for $ac_hdr" >&5
 if eval "test \"`echo '$''{'ac_cv_header_$ac_safe'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 3003 "configure"
+#line 3030 "configure"
 #include "confdefs.h"
 #include <$ac_hdr>
 EOF
 ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
-{ (eval echo configure:3008: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
+{ (eval echo configure:3035: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
 ac_err=`grep -v '^ *+' conftest.out | grep -v "^conftest.${ac_ext}\$"`
 if test -z "$ac_err"; then
   rm -rf conftest*
diff --git a/configure.in b/configure.in
index 967576b7ac..1d7e7d0ce6 100644
--- a/configure.in
+++ b/configure.in
@@ -13,7 +13,7 @@ dnl PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
 dnl ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
 dnl SOFTWARE.
 
-AC_REVISION($Revision: 1.69 $)
+AC_REVISION($Revision: 1.70 $)
 
 AC_PREREQ(2.13)
 
@@ -147,7 +147,7 @@ AC_PROG_CC
 AC_PROG_YACC
 
 AC_HEADER_STDC
-AC_CHECK_HEADERS(fcntl.h sys/time.h unistd.h sys/sockio.h)
+AC_CHECK_HEADERS(fcntl.h sys/time.h unistd.h sys/sockio.h netinet6/in6.h)
 
 AC_C_CONST
 AC_C_INLINE
@@ -350,23 +350,44 @@ AC_SUBST(A)
 dnl
 dnl IPv6
 dnl
-dnl We do this checking after libtool so that we can put
+AC_ARG_ENABLE(ipv6,
+	[  --enable-ipv6		use IPv6 [default=autodetect]])
+
+dnl
+dnl We do the IPv6 compilation checking after libtool so that we can put
 dnl the right suffix on the files.
 dnl
-AC_MSG_CHECKING(for IPv6 structures)
-AC_TRY_COMPILE([
-#include <sys/types.h>
-#include <sys/socket.h>
-#include <netinet/in.h>],
-[struct sockaddr_in6 sin6; return (0);],
-	[AC_MSG_RESULT(yes)
-	ISC_PLATFORM_HAVEIPV6="#define ISC_PLATFORM_HAVEIPV6 1"],
-	[AC_MSG_RESULT(no)
-	ISC_PLATFORM_HAVEIPV6="#undef ISC_PLATFORM_HAVEIPV6"
-	ISC_IPV6_H="ipv6.h"
-	ISC_IPV6_O="ipv6.$O"
-	ISC_ISCIPV6_O="unix/ipv6.$O"
-	ISC_IPV6_C="ipv6.c"])
+case "$enable_ipv6" in
+	yes|''|autodetect)
+		AC_MSG_CHECKING(for IPv6 structures)
+		AC_TRY_COMPILE([
+		#include <sys/types.h>
+		#include <sys/socket.h>
+		#include <netinet/in.h>],
+		[struct sockaddr_in6 sin6; return (0);],
+			[AC_MSG_RESULT(yes)
+			 found_ipv6=yes],
+			[AC_MSG_RESULT(no)
+			 found_ipv6=no])
+		;;
+	no)
+		found_ipv6=no
+		;;
+esac
+
+case "$found_ipv6" in
+	yes)
+		ISC_PLATFORM_HAVEIPV6="#define ISC_PLATFORM_HAVEIPV6 1",
+		;;
+	no)
+		ISC_PLATFORM_HAVEIPV6="#undef ISC_PLATFORM_HAVEIPV6"
+		ISC_IPV6_H="ipv6.h"
+		ISC_IPV6_O="ipv6.$O"
+		ISC_ISCIPV6_O="unix/ipv6.$O"
+		ISC_IPV6_C="ipv6.c"
+		;;
+esac
+
 AC_SUBST(ISC_PLATFORM_HAVEIPV6)
 AC_SUBST(ISC_IPV6_H)
 AC_SUBST(ISC_IPV6_O)
@@ -394,6 +415,7 @@ esac
 
 case "$use_kame" in
 	no)
+		AC_MSG_RESULT(no)
 		;;
 	*)
 		if test -f $kame_path/lib/libinet6.a; then