diff --git a/sec/ex-6_iptables.adoc b/sec/ex-6_iptables.adoc
index a85fb3b..7ee0038 100644
--- a/sec/ex-6_iptables.adoc
+++ b/sec/ex-6_iptables.adoc
@@ -218,7 +218,7 @@ X11 forwarding needs to be enabled on both the client side and the server side.
 
 [source,bash]
 ----
-ssh user@192.168.89.5 gimp
+ssh -X user@192.168.89.5 gimp
 ----
 
 == Copy Files and Directories Between Two Systems