# Two-Factor Authentication

Over the last couple of years, the primary attack vector for internet
accounts has been static passwords. Therefore static passwords are no
longer sufficient to protect unauthorized access to accounts. Two
Factor Authentication adds a variable part in authentication
procedures. A user is now required to supply a changing 6-digit
passcode in addition to their password to obtain access to the account.

LibreNMS has a RFC4226 conformant implementation of both Time and Counter
based One-Time-Passwords. It also allows the administrator to
configure a throttle time to enforce after 3 failures exceeded. Unlike
RFC4226 suggestions, this throttle time will not stack on the amount of
failures.

## Types

In general, these two types do not differ in algorithmic terms.
The types only differ in the variable being used to derive the passcodes from.
The underlying HMAC-SHA1 remains the same for both types, security
advantages or disadvantages of each are discussed further down.

### Timebased One-Time-Password (TOTP)

Like the name suggests, this type uses the current Time or a subset of
it to generate the passcodes. These passcodes solely rely on the
secrecy of their Secretkey in order to provide passcodes. An attacker
only needs to guess that Secretkey and the other variable part is any
given time, presumably the time upon login. RFC4226 suggests a
resynchronization attempt in case the passcode mismatches, providing
the attacker a range of up to +/- 3 Minutes to create passcodes.

### Counterbased One-Time-Password (HOTP)

This type uses an internal counter that needs to be in sync with the
server's counter to successfully authenticate the passcodes. The main
advantage over timebased OTP is the attacker doesn't only need to know
the Secretkey but also the server's Counter in order to create valid
passcodes. RFC4226 suggests a resynchronization attempt in case the
passcode mismatches, providing the attacker a range of up to +4
increments from the actual counter to create passcodes.

## Configuration

### WebUI

Enable 'Two-Factor' Via Global Settings in the Web UI under
Authentication -> General Authentication Settings.

Optionally enter a throttle timer in seconds. This will unlock an account 
after this time once it has failed 3 attempt to authenticate. Set to 0 (default) 
to disable this feature, meaning accounts will remain locked after 3 attempts 
and will need an administrator to clear.

### CLI

Enable Two-Factor:

`./lnms config:set twofactor true`


Set throttle-time (in seconds):

`./lnms config:set twofactor_lock 300`

## User Administration

If Two-Factor is enabled, the Settings -> Manage Users grid will show a '2FA' column 
containing a green tick for users with active 2FA.

There is no functionality to mandate 2FA for users.

If a user has failed 3 attempts, their account can be unlocked or 2FA disabled by 
editing the user from the Manage Users table.

If a throttle timer is set, it will unlock accounts after this time. If set to the 
default of 0, accounts will need to be manually unlocked by an administrator after 3 
failed attempts.

Locked accounts will report to the user stating to wait for the throttle time period,
or to contact the administrator if no timer set.

## End-User Enrolment

These steps imply that Two-Factor has been enabled system wide as above under Configuration.

2FA is enabled by each user once they are logged in normally:

- Go to 'My Settings' (/preferences/)
- Choose TwoFactor type
- Click on 'Generate TwoFactor Secret Key'
- If your browser didn't reload, reload manually
- Scan provided QR or click on 'Manual' to see the Key

### Authenticator Apps

- [Google Authenticator](https://support.google.com/accounts/answer/1066447?hl=en).
- [LastPass Authenticator](https://support.logmeininc.com/lastpass/help/lastpass-authenticator-lp030014).
- [Enpass Authenticator](https://support.enpass.io/app/item/generating_one_time_code_in_enpass.htm)).
