--- ./common/socket.c.orig	2009-07-02 16:32:44.000000000 +0200
+++ ./common/socket.c	2009-07-02 16:33:40.000000000 +0200
@@ -40,6 +40,8 @@
  * I have implemented it under Linux; other systems should be doable also.
  */
 
+#define _GNU_SOURCE
+
 #include "dhcpd.h"
 #include <errno.h>
 #include <sys/ioctl.h>