--- configure.ac	2014-01-01 18:57:39.000000000 +0200
+++ configure.ac	2014-03-19 02:43:40.440612214 +0200
@@ -9,6 +9,46 @@
 
 AC_PROG_INSTALL
 AC_PROG_CC
+AC_CANONICAL_HOST
+
+case "$host" in
+*-*-linux*)
+	AC_DEFINE([LLADDR(s)], [s->sll_addr], [the link level address])
+;;
+*-*-freebsd*)
+	AC_DEFINE([sockaddr_ll], [sockaddr_dl], [the socket link structures])
+	AC_DEFINE([sll_family], [sdl_family], [the socket family member])
+	AC_DEFINE([AF_PACKET], [AF_LINK], [the domain name])
+	AC_DEFINE([ifr_hwaddr], [ifr_addr], [the address member])
+	AC_DEFINE([SIOCSIFHWADDR], [SIOCSIFLLADDR], [the ioctl call])
+;;
+esac
+
+AC_MSG_CHECKING([if sockaddr has the sa_len member])
+AC_LINK_IFELSE(
+	[AC_LANG_PROGRAM(
+		[[ #include <sys/socket.h> ]],
+		[[ struct sockaddr sock; return (sock.sa_len); ]])],
+	[AC_DEFINE([HAVE_SOCKADDR_SA_LEN], [1],
+		   [socket address structures have length fields])
+])
+
+AC_CHECK_HEADER([ifaddrs.h], ,[AC_MSG_ERROR(
+	[*** ifaddrs.h missing - please install first or check config.log ***])])
+
+AC_CHECK_HEADERS([linux/if_packet.h net/if_dl.h])
+
+if test "x$ac_cv_header_linux_if_packet_h" = "xyes" ; then
+	AC_DEFINE([HAVE_IF_PACKET], [1],
+		    [The Linux if_packet.h header found])
+elif test "x$ac_cv_header_net_if_dl_h" = "xyes" ; then
+	AC_DEFINE([HAVE_IF_DL], [1],
+		    [The BSD if_dl.h header found])
+else
+	AC_MSG_ERROR([*** sockaddr_* missing - please install first or check config.log ***])
+fi
+
+AC_CHECK_HEADER(linux/ethtool.h, AC_DEFINE([HAVE_ETHTOOL], [1], [Linux ethernet headers found]), )
 
 AC_OUTPUT([
 Makefile