anchor.diff:  |etcd requires this port be open between masters for leader election and peering
   connections when using standalone etcd (clustered).
   
  -| *4001*
  +| *4001 (L)*
   |Used for embedded etcd (non-clustered) to accept changes in state.
   
  -| *4789*
  +| *4789 (L)*
   |Required for SDN communication between pods on separate hosts.
   
   | *9000*
  
positive.code: |The master proxies to node hosts via the Kubelet for `oc` commands.
  |===
  
  .Master to Master
  [cols='2,8']
  |===
  | *53* or *8053*
  |Required for DNS resolution of cluster services (SkyDNS).
  ifdef::openshift-origin[]
  Installations prior to 1.2 or environments upgraded to 1.2 use port 53.
  
negative.code: endif::[]
  New installations will use 8053 by default so that *dnsmasq* may be configured.
  
  | *2049* (L)
  |Required when provisioning an NFS host as part of the installer.
  
  | *2379*
  