diff --git a/sec/ex-3_iptables.adoc b/sec/ex-3_iptables.adoc
index f90c916..5a2311f 100644
--- a/sec/ex-3_iptables.adoc
+++ b/sec/ex-3_iptables.adoc
@@ -380,7 +380,12 @@ First of all, our computer is not a router (unless, of course, it is a router).
 
 === Examples
 
-We are going to use Shorewall as an iptables configuration tool. See Appendix.
+[NOTE]
+====
+We are going to use Shorewall as an iptables configuration tool. 
+
+See Appendix.
+====
 
 Here are some examples of "raw" iptables command lines.