# Upstream Bind Settings

These settings affect how Pomerium will connect to an [upstream](https://www.pomerium.com/docs/internals/glossary.md#upstream--downstream) service.

## Source Address

By default, Pomerium relies on the OS to pick an appropriate network interface for outgoing connections to an upstream service.

To override the default, you can set a specific **Source Address**. All connections to upstream services will be bound to this address.

### How to configure

**Core:**

| **Config file key** | **Environment variable** | **Type** |
| :-- | :-- | :-- |
| `envoy_bind_config_source_address` | `ENVOY_BIND_CONFIG_SOURCE_ADDRESS` | `string` |

### Example

```yaml
envoy_bind_config_source_address: 10.1.2.3
```

**Enterprise:**

**Source Address** is not configurable in the Enterprise Console.

**Kubernetes:**

**Source Address** is not configurable by the Pomerium Ingress Controller.

## Freebind

The **Freebind** option sets the `IP_FREEBIND` socket option on upstream connections. This option is supported only on Linux.

### How to configure

**Core:**

| **Config file keys**         | **Environment variables**    | **Type**  |
| :--------------------------- | :--------------------------- | :-------- |
| `envoy_bind_config_freebind` | `ENVOY_BIND_CONFIG_FREEBIND` | `boolean` |

### Example

```yaml
envoy_bind_config_freebind: true
```

**Enterprise:**

**Freebind** is not configurable in the Enterprise Console.

**Kubernetes:**

**Freebind** is not configurable by the Pomerium Ingress Controller.