## Connection and authentication issues

URL: https://docs.atlan.com/apps/connectors/data-lakehouses/dremio/troubleshooting/connection-and-authentication-issues

> Troubleshoot Dremio connection and authentication issues with error, cause, and solution guidance.

Resolve common connection and authentication issues when integrating Dremio with Atlan.

## Connection refused

::::danger Error
**Connection refused: Unable to connect to Dremio instance**
::::

### Cause

The Dremio instance isn't available from Atlan, or the REST API isn't enabled.

### Solution

1. Verify that Dremio is running and available.
2. Check that the REST API is enabled in Dremio admin settings.
3. Confirm the host and port are correct:
 * **Dremio Cloud**: Port 443 (HTTPS)
 * **Dremio on-premises**: Port 9047 (HTTPS)
4. Test connectivity from Atlan environment:
 ```bash
 # For Dremio Cloud
 curl -k https://your-dremio-host:443/api/v3/info

 # For Dremio on-premises
 curl -k https://your-dremio-host:9047/api/v3/info
 ```
5. Check firewall rules to make sure the correct port is open.

---

## Authentication failed

::::danger Error
**Authentication failed: Invalid credentials**
::::

### Cause

The provided username/password or Personal Access Token (PAT) is incorrect, or the user account doesn't exist.

### Solution

1. **For username/password authentication**:
 * Verify the username and password are correct
 * Check that the user account exists in Dremio
 * Test authentication with a simple API call:
 ```bash
 curl -k -u username:password https://your-dremio-host:9047/api/v3/info
 ```
2. **For PAT authentication**:
 * Verify the PAT token is valid and not expired
 * Check that the PAT was generated for the correct user
 * Test authentication with the PAT:
 ```bash
 curl -k -H "Authorization: Bearer YOUR_PAT_TOKEN" https://your-dremio-host:9047/api/v3/info
 ```
3. Make sure the user has appropriate permissions.
4. Reset the password or generate a new PAT if necessary.

---

## SSL certificate error

::::danger Error
**SSL certificate verification failed**
::::

### Cause

The SSL certificate is invalid, expired, or self-signed.

### Solution

1. Check the certificate validity and expiration date.
2. For self-signed certificates, add the certificate to Atlan's trust store.
3. Consider using a valid SSL certificate from a trusted CA.
4. If using HTTP instead of HTTPS, make sure it's acceptable for your security requirements.

---

## Permission denied

::::danger Error
**Permission denied: Insufficient privileges**
::::

### Cause

The user account doesn't have the required permissions to access data sources or spaces.

### Solution

1. Verify the user has read access to all required data sources.
2. Check that the user has access to spaces containing your datasets.
3. Make sure the user has appropriate permissions for the data sources and spaces you want to crawl.
4. Review and update user permissions in Dremio admin settings.

---

## Timeout error

::::danger Error
**Request timeout: Connection timed out**
::::

### Cause

Network latency is too high or the connection is unstable.

### Solution

1. Check network connectivity between Atlan and Dremio.
2. Verify that network latency is under 100ms.
3. Make sure sufficient bandwidth is available.
4. Check for any network interruptions or packet loss.
5. Consider using a VPN if Dremio is in a private network.

---

## Need help

If you continue to face issues, contact Atlan support by [submitting a support request](https://docs.atlan.com/support/submit-request).

---