Merge branch '7388-ensure-geo-documentation-contains-required-tcp-udp-ports-listed-docs'

doc/administration/geo/replication/index.md

@@ -89,6 +89,27 @@ Note that CentOS 6 and 7.0 ship with an old version of OpenSSH that do not
 support a feature that Geo requires. See the [documentation on Geo SSH
 access][fast-ssh-lookup] for more details.
 
+### Firewall rules
+
+The following table lists basic ports that must be open between the primary and secondary nodes for Geo.
+
+| Primary server | Server secondary | Protocol        |
+| -------------- | ---------------- | --------------- |
+| 80             | 80               | HTTP            |
+| 443            | 443              | TCP or HTTPS    |
+| 22             | 22               | TCP             |
+| 5432           |                  | PostgreSQL      |
+
+See the full list of ports used by GitLab in [Package defaults](https://docs.gitlab.com/omnibus/package-information/defaults.html)
+
+NOTE: **Note:**
+[Web terminal](../../../ci/environments.md#web-terminals) support requires your load balancer to correctly handle WebSocket connections.
+When using HTTP or HTTPS proxying, your load balancer must be configured to pass through the `Connection` and `Upgrade` hop-by-hop headers. See the [web terminal](../../integration/terminal.md) integration guide for more details.
+
+NOTE: **Note:**
+When using HTTPS protocol for port 443, you will need to add an SSL certificate to the load balancers.
+If you wish to terminate SSL at the GitLab application server instead, use TCP protocol.
+
 ### LDAP
 
 We recommend that if you use LDAP on your primary that you also set up a