# Networking basics

This section will help you with basic proxy and network configuration to:

- set the proxy's IP address and port
- set the proxy's REST API IP address and port
- configure the Hub if the Proxy or Spawners are remote or isolated

## Set the Proxy's IP address and port

The Proxy's main IP address setting determines where JupyterHub is available to users.
By default, JupyterHub is configured to be available on all network interfaces
(`''`) on port 8000. *Note*: Use of `'*'` is discouraged for IP configuration;
instead, use of `'0.0.0.0'` is preferred.

Changing the Proxy's main IP address and port can be done with the following
JupyterHub **command line options**:

```bash
jupyterhub --ip=192.168.1.2 --port=443
```

Or by placing the following lines in a **configuration file**,
`jupyterhub_config.py`:

```python
c.JupyterHub.ip = '192.168.1.2'
c.JupyterHub.port = 443
```

Port 443 is used in the examples since 443 is the default port for SSL/HTTPS.

Configuring only the main IP and port of JupyterHub should be sufficient for
most deployments of JupyterHub. However, more customized scenarios may need
additional networking details to be configured.

## Set the Proxy's REST API communication IP address and port (optional)

By default, this REST API listens on port 8081 of `localhost` only.
The Hub service talks to the proxy via a REST API on a secondary port. This
network interface and port can be configured separately and override the
default settings.

If running the Proxy separate from the Hub, configure the REST API communication
IP address and port by adding this to the `jupyterhub_config.py` file:

```python
# ideally a private network address
c.JupyterHub.proxy_api_ip = '10.0.1.4'
c.JupyterHub.proxy_api_port = 5432
```

## Configure the Hub if the Proxy or Spawners are remote or isolated

The Hub service listens only on `localhost` (port 8080) by default.
The Hub needs to be accessible from both the proxy and all Spawners.
When spawning local servers, an IP address setting of `localhost` is fine.

If *either* the Proxy *or* (more likely) the Spawners will be remote or
isolated in containers, the Hub must listen on an IP that is accessible.

```python
c.JupyterHub.hub_ip = '10.0.1.4'
c.JupyterHub.hub_port = 54321
```