--- Net2/netinet/ip_icmp.h	2018/04/24 18:03:54	1.1.1.1
+++ Net2/netinet/ip_icmp.h	2018/04/24 18:13:44	1.1.1.2
@@ -30,9 +30,13 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	@(#)ip_icmp.h	7.5 (Berkeley) 6/28/90
+ *	from: @(#)ip_icmp.h	7.5 (Berkeley) 6/28/90
+ *	ip_icmp.h,v 1.3 1993/05/20 03:50:22 cgd Exp
  */
 
+#ifndef _NETINET_IP_ICMP_H_
+#define _NETINET_IP_ICMP_H_
+
 /*
  * Interface Control Message Protocol Definitions.
  * Per RFC 792, September 1981.
@@ -131,3 +135,5 @@ struct icmp {
 	(type) == ICMP_TSTAMP || (type) == ICMP_TSTAMPREPLY || \
 	(type) == ICMP_IREQ || (type) == ICMP_IREQREPLY || \
 	(type) == ICMP_MASKREQ || (type) == ICMP_MASKREPLY)
+
+#endif /* !_NETINET_IP_ICMP_H_ */