Clarification of Network ACL rules and Security group rules (apache#568)

Author: weizhouapache

source/adminguide/networking/security_groups.rst

@@ -216,6 +216,11 @@ Adding Ingress and Egress Rules to a Security Group
 #. Click Add.
 
 
+.. note::
+- If there is no Egress rule in a Security Group, all the outgoing traffic will be allowed
+- If there are Egress rules in a Security Group, only the outgoing traffic which match a Egress rule will be allowed
+- Only the incoming traffic which match a Ingress rule will be allowed
+
 .. |httpaccess.png| image:: /_static/images/http-access.png
    :alt: allows inbound HTTP access from anywhere.
 

source/adminguide/networking/virtual_private_cloud_config.rst

@@ -355,6 +355,8 @@ Afterwards traffic can be white- or blacklisted.
 - ACL rules for ingress and egress are not correlating. For example a
   egress "deny all" won't affect traffic in response to an allowed ingress
   connection
+- The incoming traffic which does not match any ACL rules will be denied
+- The outgoing traffic which does not match any ACL rules will be allowed
 
 
 Creating ACLs