diff --git a/README.md b/README.md
index 9b3a4f6..cd761f4 100644
--- a/README.md
+++ b/README.md
@@ -79,7 +79,7 @@ done < /project/hosts
 See 
 
 - <a href="http://docs.swarmlab.io/SwarmLab-HowTos/labs/sec/ex-1_iptables.adoc.html" target="_new">Sec1</a>
-- [sec2](http://docs.swarmlab.io/SwarmLab-HowTos/labs/sec/ex-2_iptables.adoc.html){target="_blank"} 
+- [sec2](http://docs.swarmlab.io/SwarmLab-HowTos/labs/sec/ex-2_iptables.adoc.html){target="_blank" rel="noopener"} 
 - [sec3](http://docs.swarmlab.io/SwarmLab-HowTos/labs/sec/ex-3_iptables.adoc.html){target="_blank"} 
 - [sec4](http://docs.swarmlab.io/SwarmLab-HowTos/labs/sec/ex-3a_iptables-flow-chart.adoc.html){target="_blank"}