Merge branch '4.11'
diff --git a/source/networking/security_groups.rst b/source/networking/security_groups.rst
index 8ef58b8..262e6dd 100644
--- a/source/networking/security_groups.rst
+++ b/source/networking/security_groups.rst
@@ -86,6 +86,18 @@
advanced zones rather than multiple VLANs allows a greater range of
options for setting up guest isolation in a cloud.
+Setting for CentOS
+^^^^^^^^^^^^^^^^^^
+
+To use security groups on CentOS/RHEL/Fedora please enable bridge based
+filtering, ensure that default sysctl configuration file usually at
+/usr/lib/sysctl.d/00-system.conf set to following and run 'sysctl -p':
+
+.. note::
+ # Enable netfilter on bridges.
+ net.bridge.bridge-nf-call-ip6tables = 1
+ net.bridge.bridge-nf-call-iptables = 1
+ net.bridge.bridge-nf-call-arptables = 1
Limitations
^^^^^^^^^^^
