-#include <sys/socket.h> /* socket library */
-#include <stdio.h> /* include standard I/O library */
-#include <errno.h> /* include error codes */
-#include <string.h> /* include erroro strings definitions */
+#include <sys/socket.h> /* socket constants, types and functions */
+#include <stdio.h> /* standard I/O library */
+#include <errno.h> /* error definitions and routines */
+#include <string.h> /* C strings library */
+#include <stdlib.h> /* C standard library */
+#include <netinet/tcp.h> /* TCP constants and types */
+
+/* still not defined in some include, because too new ... */
+#ifndef TCP_CONGESTION
+#define TCP_CONGESTION 13
+#endif
+
+