--- Net2/netinet/in_pcb.h	2018/04/24 18:03:54	1.1
+++ Net2/netinet/in_pcb.h	2018/04/24 18:13:56	1.1.1.2
@@ -30,9 +30,13 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	@(#)in_pcb.h	7.6 (Berkeley) 6/28/90
+ *	from: @(#)in_pcb.h	7.6 (Berkeley) 6/28/90
+ *	in_pcb.h,v 1.3 1993/05/20 03:50:06 cgd Exp
  */
 
+#ifndef _NETINET_IN_PCB_H_
+#define _NETINET_IN_PCB_H_
+
 /*
  * Common structure pcb for internet protocol implementation.
  * Here are stored pointers to local and foreign host table
@@ -89,3 +93,5 @@ struct raw_inpcb {
 #ifdef KERNEL
 struct	inpcb *in_pcblookup();
 #endif
+
+#endif /* !_NETINET_IN_PCB_H_ */