Sandbox

After a user submits their username, the portal creates a sandbox session where the user must complete a sequence of checkpoints before a JWT is issued. The sequence follows this order:

1. Portal looks up the user in the identity store and runs configured transformers
2. Portal creates a sandbox session with the resulting checkpoint sequence and redirects the user to /sandbox/{session_id}
3. User completes each checkpoint in order (password, then MFA if required)
4. When all checkpoints pass, the portal issues a JWT

The sandbox session is separate from the final JWT session. It uses its own cookie (SandboxID) and a temporary secret. The session expires after 5 minutes regardless of activity. If it expires, the user is redirected back to the login page.

Checkpoints

The checkpoint sequence is built at login from two sources:

1. Identity store defaults -- typically password authentication
2. Transformer rules -- directives like require mfa add additional checkpoints

The sandbox processes checkpoints in order. A user who must provide both a password and a second factor will see the password form first, then the MFA form.

Password

The user enters their password. After 5 consecutive failed attempts the sandbox session is terminated.

If the user has forgotten their password, the sandbox provides a password recovery flow at the same step.

MFA

The MFA checkpoint behavior depends on what tokens the user has registered:

User has	What happens
No tokens registered	Forced to register a token before proceeding
Authenticator app only	Prompted for TOTP code
Hardware token only	Prompted for WebAuthn challenge
Both app and hardware token	Chooses which method to use

Registration counts as passing the checkpoint.

For adding MFA tokens outside the login flow, see Multi-Factor Authentication.

Configuration

Password-only login requires no additional configuration. The sandbox runs automatically.

The following configuration adds MFA as a required checkpoint using the require mfa directive inside transform user:

{
  security {
    local identity store localdb {
      realm local
      path {$HOME}/.local/caddy/users.json
    }

    authentication portal myportal {
      enable identity store localdb
      transform user {
        match realm local
        require mfa
      }
    }
  }
}

auth.myfiosgateway.com {
  authenticate with myportal
}

With this configuration, every user in the local realm must complete both a password checkpoint and an MFA checkpoint at login. If the user has not registered any MFA token, the sandbox will require them to register one before login completes.

Terminating a Session

A user can end their sandbox session early by visiting /sandbox/{id}/terminate, which redirects back to the login page.