I want to continue with a conversation we had in the past. Here is for context. Wait for my question.

I asked you this: I use nginx proxy manager to proxy the services on my server to subdomains and at the same time secure data through HTTPS. Could I also implement authentication somehow for when the services are accessed?

And you responded this:
Yes, you can implement authentication in Nginx Proxy Manager to restrict access to certain services. There are several ways to set up authentication, depending on your needs. Here are a few options:
### 1. Basic Authentication
Nginx Proxy Manager supports basic HTTP authentication, which prompts users for a username and password before they can access a service.
To set this up:1. Open Nginx Proxy Manager and go to the "Hosts" menu.2. Select the Proxy Host you want to protect.3. Go to the "Advanced" tab.4. Enable the "Access List" option and create a new access list.5. In the access list settings, add users with their respective passwords.6. Save the changes, and now when someone accesses that subdomain, they'll be prompted to enter the credentials.
*Note:* Basic authentication is a straightforward method but not the most secure for sensitive services, as passwords are sent in base64-encoded format.
### 2. IP Whitelisting
For additional security, you could restrict access to specific IP addresses, allowing only trusted networks to access the services.
To do this:1. Go to the "Access List" for your Proxy Host.2. Add a new access list, and in the "Authorization" section, specify only the allowed IP addresses or CIDR ranges.3. Save the configuration.
This is ideal if you need to limit access to specific users or networks.
### 3. Integrating with OAuth / External Authentication
For more robust authentication, consider using an external authentication provider (such as OAuth with Google, GitHub, etc.) or an external authentication service like Authelia, Keycloak, or Authentik. This way, you can use Single Sign-On (SSO) and multi-factor authentication (MFA).
**Example using Authelia**:1. Install Authelia and configure it according to your authentication requirements (like 2FA, LDAP integration, etc.).2. In Nginx Proxy Manager, set up a custom location for your Proxy Host.3. In the custom configuration for the location, use `auth_request` to send an authentication request to Authelia before accessing the main service.
A configuration snippet for Nginx Proxy Manager with Authelia might look like this:
```nginxlocation / {    # Forward authentication to Authelia    auth_request /authelia-auth;
    # Pass actual requests to your service    proxy_pass http://your-service;}
location = /authelia-auth {    internal;    proxy_pass http://authelia-server/api/verify;    proxy_set_header X-Original-URI $request_uri;    proxy_set_header X-Real-IP $remote_addr;    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;    proxy_set_header X-Forwarded-Host $host;}```
This setup allows you to use SSO and MFA with your services.
### 4. Client-Side SSL Certificates (Mutual TLS Authentication)
If you require a high level of security, you can also configure Nginx to require client-side SSL certificates. This way, users need to have a valid certificate installed in their browser to access the services.
To implement this:1. Issue client certificates to users and distribute them securely.2. In Nginx Proxy Manager, configure the SSL settings to require client certificates for the particular proxy host.
### Summary
- **Basic Authentication**: Easy to set up but less secure.- **IP Whitelisting**: Adds a layer of restriction based on IP.- **OAuth / SSO with Authelia**: Allows advanced authentication, including SSO and 2FA.- **Mutual TLS**: Provides strong security but requires managing client certificates.
Choose the method that best fits your security and usability needs. For most use cases, a combination of OAuth/SSO and IP whitelisting is effective, while Mutual TLS is suited for very high-security environments.