--- Net2/netinet/tcp_var.h	2018/04/24 18:03:54	1.1.1.1
+++ Net2/netinet/tcp_var.h	2018/04/24 18:13:50	1.1.1.2
@@ -30,9 +30,13 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	@(#)tcp_var.h	7.10 (Berkeley) 6/28/90
+ *	from: @(#)tcp_var.h	7.10 (Berkeley) 6/28/90
+ *	tcp_var.h,v 1.3 1993/05/20 03:50:42 cgd Exp
  */
 
+#ifndef _NETINET_TCP_VAR_H_
+#define _NETINET_TCP_VAR_H_
+
 /*
  * Kernel variables for tcp.
  */
@@ -216,3 +220,5 @@ struct	tcpiphdr *tcp_template();
 struct	tcpcb *tcp_close(), *tcp_drop();
 struct	tcpcb *tcp_timers(), *tcp_disconnect(), *tcp_usrclosed();
 #endif
+
+#endif /* !_NETINET_TCP_VAR_H_ */