--- Net2/netinet/tcp.h	2018/04/24 18:03:54	1.1
+++ Net2/netinet/tcp.h	2018/04/24 18:13:35	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.h	7.7 (Berkeley) 6/28/90
+ *	from: @(#)tcp.h	7.7 (Berkeley) 6/28/90
+ *	tcp.h,v 1.3 1993/05/20 03:50:31 cgd Exp
  */
 
+#ifndef _NETINET_TCP_H_
+#define _NETINET_TCP_H_
+
 typedef	u_long	tcp_seq;
 /*
  * TCP header.
@@ -82,3 +86,5 @@ struct tcphdr {
  */
 #define	TCP_NODELAY	0x01	/* don't delay send to coalesce packets */
 #define	TCP_MAXSEG	0x02	/* set maximum segment size */
+
+#endif /* !_NETINET_TCP_H_ */