enigma-bbs/docs/configuration/security.md

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---
layout: page
title: Security
---
## Security
Unlike in the golden era of BBSing, modern Internet-connected systems are prone to hacking attempts, eavesdropping, etc. While plain-text passwords, insecure data over [Plain Old Telephone Service (POTS)](https://en.wikipedia.org/wiki/Plain_old_telephone_service), and so on was good enough then, modern systems must employ protections against attacks. ENiGMA½ comes with many security features that help keep the system and your users secure — not limited to:
* Passwords are **never** stored in plain-text, but instead are stored using [Password-Based Key Derivation Function 2 (PBKDF2)](https://en.wikipedia.org/wiki/PBKDF2). Even the system operator can _never_ know your password!
* Alternatives to insecure Telnet logins are built in: [SSH](https://en.wikipedia.org/wiki/Secure_Shell) and secure [WebSockets](https://en.wikipedia.org/wiki/WebSocket) for example.
* A built in web server with [TLS](https://en.wikipedia.org/wiki/Transport_Layer_Security) support (aka HTTPS).
* Optional [Two-Factor Authentication (2FA)](https://en.wikipedia.org/wiki/Multi-factor_authentication) via [One-Time-Password (OTP)](https://en.wikipedia.org/wiki/One-time_password) for users, supporting [Google Authenticator](http://google-authenticator.com/), [Time-Based One-Time Password Algorithm (TOTP, RFC-6238)](https://tools.ietf.org/html/rfc6238), and [HMAC-Based One-Time Password Algorithm (HOTP, RFC-4266)](https://tools.ietf.org/html/rfc4226).
## Two-Factor Authentication via One-Time Password
Enabling Two-Factor Authentication via One-Time-Password (2FA/OTP) on an account adds an extra layer of security ("_something a user has_") in addition to their password ("_something a user knows_"). Providing 2FA/OTP to your users has some prerequisites:
* [A configured email gateway](/docs/configuration/email.md) such that the system can send out emails.
* One or more secure servers enabled such as [SSH](/docs/servers/ssh.md) or secure [WebSockets](/docs/servers/websocket.md) (that is, WebSockets over a secure connection such as TLS).
* The [web server](/docs/servers/web-server.md) enabled and exposed over TLS (HTTPS).
:information_source: For WebSockets and the web server, ENiGMA½ _may_ listen on insecure channels if behind a secure web proxy.
### User Registration Flow
Due to the nature of 2FA/OTP, even if enabled on your system, users must opt-in and enable this feature on their account. Users must also have a valid email address such that a registration link can be sent to them. To opt-in, a process similar to the following is taken:
1. Navigate to the 2FA/OTP configuration menu and switches the feature to enabled.
2. Selects the "flavor" of 2FA/OTP: Google Authenticator, TOTP, or HOTP.
3. Confirms settings by saving.
After saving, a registration link will be mailed to the user. Clicking the link provides the following:
1. A secret for manual entry into a OTP device.
2. If applicable, a scannable QR code for easy device entry (e.g. Google Authenticator)
3. A confirmation prompt in which the user must enter a OTP code. If entered correctly, this validates everything is set up properly and 2FA/OTP will be enabled for the account. Future logins will now prompt the user for their OTP after they enter their standard password.
:warning: Serving 2FA/OTP registration links over insecure (HTTP) can expose secrets intended for the user and is **highly** discouraged!
:information_source: +ops can also manually enable or disable 2FA/OTP for a user using [oputil](/docs/admin/oputil.md), but this is generally discouraged.
### ACS Checks
Various places throughout the system that implement [ACS](/docs/configuration/acs.md) can make 2FA specific checks:
* `AR#`: Current users **required** authentication factor. `AR2` for example means 2FA/OTP is required for this user.
* `AF#`: Current users **active** authentication factor. `AF2` means the user is authenticated with some sort of 2FA (such as One-Time-Password).
See [ACS](/docs/configuration/acs.md) for more information.
#### Example
The following example illustrates using an `AR` ACS check to require applicable users to go through an additional 2FA/OTP process during login:
```hjson
login: {
art: USERLOG
next: [
{
// users with AR2+ must first pass 2FA/OTP
acs: AR2
next: loginTwoFactorAuthOTP
}
{
// everyone else skips ahead
next: fullLoginSequenceLoginArt
}
]
// ...
}
```