---
layout: docs
page_title: Connect - Built-in Proxy
description: Consul Connect comes with a built-in proxy for testing and development.
---

# Built-In Proxy Options

Consul comes with a built-in L4 proxy for testing and development with Consul
Connect.

~> **Note:** [Envoy](/docs/connect/proxies/envoy) should be used for production deployments, or when [layer 7 traffic management](/docs/connect/l7-traffic-management) features are needed.

## Getting Started

To get started with the built-in proxy and see a working example you can follow the [Getting Started](https://learn.hashicorp.com/tutorials/consul/get-started-service-networking) tutorial.

## Proxy Config Key Reference

Below is a complete example of all the configuration options available
for the built-in proxy.

```javascript
{
  "service": {
    ...
    "connect": {
      "proxy": {
        "config": {
          "bind_address": "0.0.0.0",
          "bind_port": 20000,
          "tcp_check_address": "192.168.0.1",
          "disable_tcp_check": false,
          "local_service_address": "127.0.0.1:1234",
          "local_connect_timeout_ms": 1000,
          "handshake_timeout_ms": 10000,
          "upstreams": [...]
        },
        "upstreams": [
          {
            ...
            "config": {
              "connect_timeout_ms": 1000
            }
          }
        ]
      }
    }
  }
}
```

All fields are optional with a sane default.

- `bind_address` - The address the proxy will bind its
  _public_ mTLS listener to. It defaults to the same address the agent binds to.

- `bind_port` - The port the proxy will bind its _public_
  mTLS listener to. If not provided, the agent will attempt to assign one from its
  [configured proxy port range](/docs/agent/options#sidecar_min_port) if available.
  By default the range is [20000, 20255] and the port is selected at random from
  that range.

- `tcp_check_address` - The address the agent will
  run a [TCP health check](/docs/agent/checks) against. By default this is the same
  as the proxy's [bind address](#bind_address) except if the bind address is `0.0.0.0`
  or `[::]` in which case this defaults to `127.0.0.1` and assumes the agent can
  dial the proxy over loopback. For more complex configurations where agent and proxy
  communicate over a bridge for example, this configuration can be used to specify
  a different _address_ (but not port) for the agent to use for health checks if
  it can't talk to the proxy over localhost or its publicly advertised port. The
  check always uses the same port that the proxy is bound to.

- `disable_tcp_check` - If true, this disables a
  TCP check being setup for the proxy. Default is false.

- `local_service_address`- The `[address]:port`
  that the proxy should use to connect to the local application instance. By default
  it assumes `127.0.0.1` as the address and takes the port from the service definition's
  `port` field. Note that allowing the application to listen on any non-loopback
  address may expose it externally and bypass Connect's access enforcement. It may
  be useful though to allow non-standard loopback addresses or where an alternative
  known-private IP is available for example when using internal networking between
  containers.

- `local_connect_timeout_ms` - The number
  of milliseconds the proxy will wait to establish a connection to the _local application_
  before giving up. Defaults to `1000` or 1 second.

- `handshake_timeout_ms` - The number of milliseconds
  the proxy will wait for _incoming_ mTLS connections to complete the TLS handshake.
  Defaults to `10000` or 10 seconds.

- `upstreams`- **Deprecated** Upstreams are now specified
  in the `connect.proxy` definition. Upstreams specified in the opaque config map
  here will continue to work for compatibility but it's strongly recommended that
  you move to using the higher level [upstream configuration](/docs/connect/registration/service-registration#upstream-configuration-reference).

## Proxy Upstream Config Key Reference

All fields are optional with a sane default.

- `connect_timeout_ms` - The number of milliseconds
  the proxy will wait to establish a TLS connection to the discovered upstream instance
  before giving up. Defaults to `10000` or 10 seconds.
