docs/content/admin/enterprise-management/configuring-clustering/cluster-network-configuration.md

title, intro, product, redirect_from, versions, type, topics, shortTitle

title	intro	product	redirect_from	versions	type	topics	shortTitle
Cluster network configuration	A {% data variables.product.prodname_ghe_server %} cluster requires proper DNS name resolution, load balancing, and communication between nodes.	{% data reusables.gated-features.cluster %}	/enterprise/admin/clustering/cluster-network-configuration /enterprise/admin/enterprise-management/cluster-network-configuration /admin/enterprise-management/cluster-network-configuration	ghes *	reference	Clustering Enterprise Infrastructure Networking	Configure a cluster network

About networking for a {% data variables.product.product_name %} cluster

Each node in your {% data variables.product.product_name %} cluster must be able to communicate with all of the other nodes in the cluster over the network. You can review the required ports and protocols for end users, administration, and communication between nodes. To distribute traffic among front-end nodes, {% data variables.product.company_short %} recommends that you configure an external load balancer.

Network considerations

The simplest network design for clustering is to place the nodes on a single LAN. If a cluster must span subnetworks, we do not recommend configuring any firewall rules between the networks. The latency between nodes should be less than 1 millisecond.

{% data reusables.enterprise_clustering.network-latency %}

• Application ports for end users
• Administrative ports
• Cluster communication ports

Application ports for end users

Application ports provide web application and Git access for end users.

Port	Description	Encrypted
22/TCP	Git over SSH	{% octicon "check" aria-label="Encrypted" %}
25/TCP	SMTP	Requires STARTTLS
80/TCP	HTTP	{% octicon "x" aria-label="Not encrypted" %} When SSL is enabled this port redirects to HTTPS
443/TCP	HTTPS	{% octicon "check" aria-label="Encrypted" %}
9418/TCP	Simple Git protocol port (Disabled in private mode)	{% octicon "x" aria-label="Not encrypted" %}

Administrative ports

Administrative ports are not required for basic application use by end users.

Port	Description	Encrypted
ICMP	ICMP Ping	{% octicon "x" aria-label="Not encrypted" %}
122/TCP	Administrative SSH	{% octicon "check" aria-label="Encrypted" %}
161/UDP	SNMP	{% octicon "x" aria-label="Not encrypted" %}
8080/TCP	Management Console HTTP	{% octicon "x" aria-label="Not encrypted" %} When SSL is enabled this port redirects to HTTPS
8443/TCP	Management Console HTTPS	{% octicon "check" aria-label="Encrypted" %}

Cluster communication ports

If a network level firewall is in place between nodes, these ports will need to be accessible. The communication between nodes is not encrypted. These ports should not be accessible externally.

Port	Description
1336/TCP	Internal API
3033/TCP	Internal SVN access
3037/TCP	Internal SVN access
3306/TCP	MySQL
4486/TCP	Governor access
5115/TCP	Storage backend
5208/TCP	Internal SVN access
6379/TCP	Redis
8001/TCP	Grafana
8090/TCP	Internal GPG access
8149/TCP	GitRPC file server access
8300/TCP	Consul
8301/TCP	Consul
8302/TCP	Consul
9000/TCP	Git Daemon
9102/TCP	Pages file server
9105/TCP	LFS server
9200/TCP	Elasticsearch
9203/TCP	Semantic code service
9300/TCP	Elasticsearch
11211/TCP	Memcache
161/UDP	SNMP
8125/UDP	Statsd
8301/UDP	Consul
8302/UDP	Consul
25827/UDP	Collectd

Configuring a load balancer

We recommend an external TCP-based load balancer that supports the PROXY protocol to distribute traffic across nodes. Consider these load balancer configurations:

• TCP ports (shown below) should be forwarded to nodes running the web-server service. These are the only nodes that serve external client requests.
• Sticky sessions shouldn't be enabled.

{% data reusables.enterprise_installation.terminating-tls %}

Handling client connection information

Because client connections to the cluster come from the load balancer, the client IP address can be lost. To properly capture the client connection information, additional consideration is required.

{% data reusables.enterprise_clustering.proxy_preference %}

{% data reusables.enterprise_clustering.proxy_xff_firewall_warning %}

Enabling PROXY support on {% data variables.product.prodname_ghe_server %}

We strongly recommend enabling PROXY support for both your instance and the load balancer.

{% data reusables.enterprise_installation.proxy-incompatible-with-aws-nlbs %}

• For your instance, use this command:

  $ ghe-config 'loadbalancer.proxy-protocol' 'true' && ghe-cluster-config-apply
  

• For the load balancer, use the instructions provided by your vendor.

{% data reusables.enterprise_clustering.proxy_protocol_ports %}

Enabling X-Forwarded-For support on {% data variables.product.prodname_ghe_server %}

{% data reusables.enterprise_clustering.x-forwarded-for %}

To enable the X-Forwarded-For header, use this command:

$ ghe-config 'loadbalancer.http-forward' 'true' && ghe-cluster-config-apply

{% data reusables.enterprise_clustering.without_proxy_protocol_ports %}

Configuring health checks

Health checks allow a load balancer to stop sending traffic to a node that is not responding if a pre-configured check fails on that node. If a cluster node fails, health checks paired with redundant nodes provides high availability.

{% data reusables.enterprise_clustering.health_checks %} {% data reusables.enterprise_site_admin_settings.maintenance-mode-status %}

DNS requirements

{% data reusables.enterprise_clustering.load_balancer_dns %}