> ## Documentation Index
> Fetch the complete documentation index at: https://docs.roundproxies.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Authentication

> Authenticate with Datacenter Proxies using username/password or IP whitelisting.

Datacenter proxies support two ways to authenticate. Pick whichever fits your setup — both can be active at the same time.

## Username & Password

The default method, and the one that works everywhere. Your credentials are included in every request:

```text theme={null}
http://{USERNAME}:{PASSWORD}@{PROXY_IP}:{PORT}
```

You'll find your username and password in the [dashboard](https://app.roundproxies.com/dashboard/datacenter), and you can reset them there at any time. Resetting takes effect within a few minutes — update any running scripts before you rotate credentials, or they'll start failing with `407` errors.

<Note>
  Some tools (older browser extensions, certain game clients) can't handle proxy credentials. If yours is one of them, use IP whitelisting instead.
</Note>

## IP Whitelisting

Instead of sending credentials, you register the IP of the machine that will use the proxies. Requests coming from a whitelisted IP go through without a username or password:

```text theme={null}
http://{PROXY_IP}:{PORT}
```

To set it up:

1. Find your server's public IP (for example via [api.ipify.org](https://api.ipify.org))
2. Add it under **IP Whitelist** in the [dashboard](https://app.roundproxies.com/dashboard/datacenter)
3. Wait a minute or two for the change to propagate, then test a request

Keep in mind:

* Whitelisting only helps if your machine has a **static** IP. If your ISP rotates your IP, requests will start failing with `407` until you update the whitelist.
* You can whitelist multiple IPs, e.g. your production server and your office.
* Remove IPs you no longer use — anyone on a whitelisted IP can use your bandwidth.

## Troubleshooting

| Problem                             | Likely cause                                         | Fix                                                                                              |
| ----------------------------------- | ---------------------------------------------------- | ------------------------------------------------------------------------------------------------ |
| `407 Proxy Authentication Required` | Wrong credentials, or your IP isn't whitelisted.     | Double-check credentials in the dashboard; confirm your current public IP matches the whitelist. |
| Works locally but not on the server | The server's IP isn't whitelisted.                   | Whitelist the server's public IP, or use username/password on the server.                        |
| Worked yesterday, fails today       | Your ISP changed your IP, or credentials were reset. | Re-check your public IP and the whitelist; confirm credentials are current.                      |

Still stuck? See [Error Handling](/datacenter/error-handling) or email [team@roundproxies.com](mailto:team@roundproxies.com).