> ## Documentation Index
> Fetch the complete documentation index at: https://nexus-core.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Configuring Nexus Core

> Set up Redis, MongoDB, and packet security for Nexus Core v1.5.1 using the web panel and the NEXUS_SIGNING_KEY environment variable.

Starting from v1.5, Nexus Core runs a Spring Boot web panel instead of the legacy Swing dashboard. All connection parameters are entered through the web UI and validated live during bootstrapping. Since v1.4.0, these parameters are persisted to a local config file, so you only need to enter them once.

## Accessing the Web Panel

After launching Nexus Core, open your browser and navigate to:

```text theme={null}
http://localhost:8080
```

Enter the connection details below and click **INITIALIZE NEXUS ENGINE**.

## Connection Parameters

| Field         | Default                     | Notes                                                                     |
| ------------- | --------------------------- | ------------------------------------------------------------------------- |
| `REDIS HOST`  | `127.0.0.1`                 | Host or IP of your Redis server. Port defaults to 6379.                   |
| `MONGO URI`   | `mongodb://localhost:27017` | Full MongoDB connection string. Supports authentication and replica sets. |
| `SERVER PORT` | `8080`                      | Port the web panel and HTTP health check endpoint listen on.              |

## Security Key

The `NEXUS_SIGNING_KEY` environment variable controls HMAC-SHA256 message authentication. Since v1.5.1, signing is fully symmetric: Nexus Core verifies signatures on **inbound** packets and also signs all **outbound** responses (including DataAddon publish operations and heartbeat messages).

Set the key before launching the process:

```bash theme={null}
export NEXUS_SIGNING_KEY="a-long-and-unpredictable-secret-key"
java -jar target/nexus-core-4.0.jar
```

<Warning>
  The same `NEXUS_SIGNING_KEY` value must be configured on every Spigot server that communicates with Nexus Core, and on Nexus Core itself. Never commit it to version control. Use a secrets manager or CI/CD environment variable and rotate it regularly.
</Warning>

<Note>
  If `NEXUS_SIGNING_KEY` is not set, both inbound verification and outbound signing are disabled. A one-time warning is logged at startup. This is acceptable only in local development environments.
</Note>

## What Gets Signed (v1.5.1)

| Direction                 | Signed?             | Fields added                                       |
| ------------------------- | ------------------- | -------------------------------------------------- |
| Spigot → Nexus (inbound)  | Yes                 | `sig`, `timestamp`, `nonce` sent by client         |
| Nexus → Spigot (outbound) | Yes (new in v1.5.1) | `sig`, `timestamp`, `nonce` added by `MessageAuth` |

## Production Checklist

* Set `NEXUS_SIGNING_KEY` on every node (Nexus Core and all Spigot servers) before deployment.
* Keep all server clocks synchronized with NTP. Timestamp validation uses a 5-minute window; drift beyond that causes valid packets to be rejected.
* Use a MongoDB URI with authentication in production (e.g. `mongodb://user:pass@host:27017/nexus_core_db`).
* Bind Redis to a private network interface and enable password authentication. Do not expose it to the public internet.

## Related Topics

* [Installation](/installation) — building and running Nexus Core from source
* [Security](/concepts/security) — how HMAC signing, timestamp validation, and nonce protection work together
* [Quickstart](/quickstart) — registering your first DataAddon


## Related topics

- [Packet Security and Replay Protection in Nexus Core](/concepts/security.md)
- [Installing Nexus Core](/installation.md)
- [Nexus Core Changelog](/reference/changelog.md)
- [Request Types in Nexus Core](/concepts/request-types.md)
- [System Architecture of Nexus Core](/concepts/architecture.md)