Index: configure.in
===================================================================
--- configure.in	(revision 1770)
+++ configure.in	(working copy)
@@ -52,7 +52,54 @@
 dnl Checks for header files.
 
 AC_HEADER_STDC
-AC_CHECK_HEADERS(unistd.h sys/ioctl.h sys/time.h termios.h ncurses.h netinet/if_ether.h netinet/ether.h)
+
+AC_CHECK_HEADERS(unistd.h sys/ioctl.h sys/time.h termios.h ncurses.h)
+
+dnl Darwin needs sys/socket.h before net/if.h
+
+AC_CHECK_HEADERS([sys/socket.h])
+AC_CHECK_HEADERS([net/if.h], [], [AC_MSG_WARN(Problems including net/if.h)],
+[
+#include <stdio.h>
+#if STDC_HEADERS
+# include <stdlib.h>
+# include <stddef.h>
+#else
+# if HAVE_STDLIB_H
+#  include <stdlib.h>
+# endif
+#endif
+#if HAVE_SYS_SOCKET_H
+# include <sys/socket.h>
+#endif
+])
+
+dnl as well as net/if.h, netbsd needs netinet/in.h if we're going to use netinet/if_ether.h
+
+AC_CHECK_HEADERS([netinet/in.h])
+
+AC_CHECK_HEADERS([netinet/if_ether.h], [], [AC_MSG_WARN(Problems including netinet/if_ether.h)],
+[
+#include <stdio.h>
+#if STDC_HEADERS
+# include <stdlib.h>
+# include <stddef.h>
+#else
+# if HAVE_STDLIB_H
+#  include <stdlib.h>
+# endif
+#endif
+#if HAVE_SYS_SOCKET_H
+# include <sys/socket.h>
+#endif
+#if HAVE_NET_IF_H
+# include <net/if.h>
+#endif
+#if HAVE_NETINET_IN_H
+# include <netinet/in.h>
+#endif
+])
+
 dnl AC_EGREP_HEADER(TIOCGWINSZ,sys/ioctl.h,AC_DEFINE(HAVE_TIOCGWINSZ))
 
 dnl Checks for typedefs, structures, and compiler characteristics.