--- Net2/net/slip.h	2018/04/24 18:13:17	1.1.1.1
+++ Net2/net/slip.h	2018/04/24 18:21:41	1.1.1.2
@@ -1,8 +1,8 @@
 /*
  * Definitions that user level programs might need to know to interact
  * with serial line IP (slip) lines.
-
- * @(#) $Header: /var/lib/cvsd/net2/Net2/net/slip.h,v 1.1.1.1 2018/04/24 18:13:17 root Exp $ (LBL)
+ *
+ *	slip.h,v 1.3 1993/05/20 03:06:14 cgd Exp
  *
  * Copyright (c) 1990 Regents of the University of California.
  * All rights reserved.
@@ -20,6 +20,9 @@
  * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  */
 
+#ifndef _NET_SLIP_H_
+#define _NET_SLIP_H_
+
 /*
  * ioctl to get slip interface unit number (e.g., sl0, sl1, etc.)
  * assigned to some terminal line with a slip module pushed on it.
@@ -43,3 +46,4 @@
 #define SLIPDIR_IN 0
 #define SLIPDIR_OUT 1
 
+#endif /* !_NET_SLIP_H_ */