--- configure.ac.bak	2003-10-22 02:06:04.000000000 +0100
+++ configure.ac	2003-10-22 02:06:12.000000000 +0100
@@ -197,12 +197,266 @@
                  libutil.h limits.h])
 
 AC_CHECK_HEADERS([sys/socket.h netinet/in.h net/if_dl.h \
-		 net/netopt.h inet/nd.h net/route.h net/if.h \
-		 net/if_var.h netinet/in_var.h])
+		 net/netopt.h inet/nd.h net/route.h])
+
+dnl FreeBSD (and other BSDs?) seem hell-bent on making it as difficult as
+dnl possible to include headers
+
+AC_CHECK_HEADERS([net/if.h], [], [],
+[#include <stdio.h>
+#if HAVE_SYS_TYPES_H
+# include <sys/types.h>
+#endif
+#if HAVE_SYS_STAT_H
+# include <sys/stat.h>
+#endif
+#if STDC_HEADERS
+# include <stdlib.h>
+# include <stddef.h>
+#else
+# if HAVE_STDLIB_H
+#  include <stdlib.h>
+# endif
+#endif
+#if HAVE_STRING_H
+# if !STDC_HEADERS && HAVE_MEMORY_H
+#  include <memory.h>
+# endif
+# include <string.h>
+#endif
+#if HAVE_STRINGS_H
+# include <strings.h>
+#endif
+#if HAVE_INTTYPES_H
+# include <inttypes.h>
+#else
+# if HAVE_STDINT_H
+#  include <stdint.h>
+# endif
+#endif
+#if HAVE_UNISTD_H
+# include <unistd.h>
+#endif
+#ifdef HAVE_SYS_SOCKET_H
+#include <sys/socket.h>
+#endif
+#ifdef HAVE_NETINET_IN_H
+#include <netinet/in.h>
+#endif
+])
+
+AC_CHECK_HEADERS([net/if_var.h], [], [],
+[#include <stdio.h>
+#if HAVE_SYS_TYPES_H
+# include <sys/types.h>
+#endif
+#if HAVE_SYS_STAT_H
+# include <sys/stat.h>
+#endif
+#if STDC_HEADERS
+# include <stdlib.h>
+# include <stddef.h>
+#else
+# if HAVE_STDLIB_H
+#  include <stdlib.h>
+# endif
+#endif
+#if HAVE_STRING_H
+# if !STDC_HEADERS && HAVE_MEMORY_H
+#  include <memory.h>
+# endif
+# include <string.h>
+#endif
+#if HAVE_STRINGS_H
+# include <strings.h>
+#endif
+#if HAVE_INTTYPES_H
+# include <inttypes.h>
+#else
+# if HAVE_STDINT_H
+#  include <stdint.h>
+# endif
+#endif
+#if HAVE_UNISTD_H
+# include <unistd.h>
+#endif
+#ifdef HAVE_SYS_SOCKET_H
+#include <sys/socket.h>
+#endif
+#ifdef HAVE_NET_IF_H
+#include <net/if.h>
+#endif
+#ifdef HAVE_NET_IF_VAR_H
+#include <net/if_var.h>
+#endif
+#ifdef HAVE_NETINET_IN_H
+#include <netinet/in.h>
+#endif
+])
+
+AC_CHECK_HEADERS([netinet/in_var.h], [], [],
+[#include <stdio.h>
+#if HAVE_SYS_TYPES_H
+# include <sys/types.h>
+#endif
+#if HAVE_SYS_STAT_H
+# include <sys/stat.h>
+#endif
+#if STDC_HEADERS
+# include <stdlib.h>
+# include <stddef.h>
+#else
+# if HAVE_STDLIB_H
+#  include <stdlib.h>
+# endif
+#endif
+#if HAVE_STRING_H
+# if !STDC_HEADERS && HAVE_MEMORY_H
+#  include <memory.h>
+# endif
+# include <string.h>
+#endif
+#if HAVE_STRINGS_H
+# include <strings.h>
+#endif
+#if HAVE_INTTYPES_H
+# include <inttypes.h>
+#else
+# if HAVE_STDINT_H
+#  include <stdint.h>
+# endif
+#endif
+#if HAVE_UNISTD_H
+# include <unistd.h>
+#endif
+#ifdef HAVE_SYS_SOCKET_H
+#include <sys/socket.h>
+#endif
+#ifdef HAVE_NET_IF_H
+#include <net/if.h>
+#endif
+#ifdef HAVE_NET_IF_VAR_H
+#include <net/if_var.h>
+#endif
+#ifdef HAVE_NETINET_IN_H
+#include <netinet/in.h>
+#endif
+])
+
 
 if test "x${enable_ipv6}" = "xyes"; then
-AC_CHECK_HEADERS([netinet6/in6.h netinet/in6_var.h netinet/icmp6.h \
-		 netinet6/in6_var.h netinet6/nd6.h])
+AC_CHECK_HEADERS([netinet6/in6.h ])
+
+AC_CHECK_HEADERS([netinet/in6_var.h netinet/icmp6.h netinet6/in6_var.h], \
+  [], [],
+[#include <stdio.h>
+#if HAVE_SYS_TYPES_H
+# include <sys/types.h>
+#endif
+#if HAVE_SYS_STAT_H
+# include <sys/stat.h>
+#endif
+#if STDC_HEADERS
+# include <stdlib.h>
+# include <stddef.h>
+#else
+# if HAVE_STDLIB_H
+#  include <stdlib.h>
+# endif
+#endif
+#if HAVE_STRING_H
+# if !STDC_HEADERS && HAVE_MEMORY_H
+#  include <memory.h>
+# endif
+# include <string.h>
+#endif
+#if HAVE_STRINGS_H
+# include <strings.h>
+#endif
+#if HAVE_INTTYPES_H
+# include <inttypes.h>
+#else
+# if HAVE_STDINT_H
+#  include <stdint.h>
+# endif
+#endif
+#if HAVE_UNISTD_H
+# include <unistd.h>
+#endif
+#ifdef HAVE_SYS_SOCKET_H
+#include <sys/socket.h>
+#endif
+#ifdef HAVE_NET_IF_H
+#include <net/if.h>
+#endif
+#ifdef HAVE_NET_IF_VAR_H
+#include <net/if_var.h>
+#endif
+#ifdef HAVE_NETINET_IN_H
+#include <netinet/in.h>
+#endif
+#ifdef HAVE_NETINET6_IN6_H
+#include <netinet6/in6.h>
+#endif
+])
+
+AC_CHECK_HEADERS([netinet6/nd6.h], [], [],
+[#include <stdio.h>
+#if HAVE_SYS_TYPES_H
+# include <sys/types.h>
+#endif
+#if HAVE_SYS_STAT_H
+# include <sys/stat.h>
+#endif
+#if STDC_HEADERS
+# include <stdlib.h>
+# include <stddef.h>
+#else
+# if HAVE_STDLIB_H
+#  include <stdlib.h>
+# endif
+#endif
+#if HAVE_STRING_H
+# if !STDC_HEADERS && HAVE_MEMORY_H
+#  include <memory.h>
+# endif
+# include <string.h>
+#endif
+#if HAVE_STRINGS_H
+# include <strings.h>
+#endif
+#if HAVE_INTTYPES_H
+# include <inttypes.h>
+#else
+# if HAVE_STDINT_H
+#  include <stdint.h>
+# endif
+#endif
+#if HAVE_UNISTD_H
+# include <unistd.h>
+#endif
+#ifdef HAVE_SYS_SOCKET_H
+#include <sys/socket.h>
+#endif
+#ifdef HAVE_NET_IF_H
+#include <net/if.h>
+#endif
+#ifdef HAVE_NET_IF_VAR_H
+#include <net/if_var.h>
+#endif
+#ifdef HAVE_NETINET_IN_H
+#include <netinet/in.h>
+#endif
+#ifdef HAVE_NETINET6_IN6_H
+#include <netinet6/in6.h>
+#endif
+#ifdef HAVE_NETINET6_IN6_VAR_H
+#include <netinet6/in6_var.h>
+#endif
+#ifdef HAVE_NETINET_IN6_VAR_H
+#include <netinet/in6_var.h>
+#endif
+])
 fi
 dnl if enable_ipv6