# Alt account detection

Staff++ provides a way to be notified when it thinks a user is using alternative accounts. The detection is really simple so don't expect miracles. It will detect the most basic and obvious alt accounts. Alt detection is disabled by default

## Configuration

```yaml
alt-detect-module:
  enabled: true
```

## How it works

### Ip similarity

When enabled the system will start recording players IP addresses. Every address a player ever connects with gets stored. If a player connects with the same address as another player his detection score is upped by 1.

### Username similarity

When a player connects we check his username against all other users known to the server. Similarity is calculated using the Levenshtein Distance Algorithm. Based on this a score is returned:

* 70% similarity --> score 3
* 50% similarity --> score 2
* 30% similarity --> score 1

### Detection trust levels (score)

The trust level is the result of the above mentioned checks. We have four levels of trust:

| Trust Level      | score | Description                                                                                                                                                                                                                                                           |
| ---------------- | ----- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| POSITIVE         | 4     | Only one case can trigger the POSITIVE level. When a username has an IP match and a username match of at least 70%. We can be fairly certain something is going on with these accounts                                                                                |
| FAIRLY\_POSITIVE | 3     | Triggered when username match is between 50% and 70% and IP is matching. Or when username match is at least 70% and IP is not matching.                                                                                                                               |
| POSSIBLE         | 2     | Triggered when username match is between 30% and 50% and IP is matching. Or when username match is between 50% and 70%, and IP is not matching.                                                                                                                       |
| NOT\_LIKELY      | 1     | Triggered when username match is between 30% and 50% and IP is not matching. Or when IP is matching but there is no username similarity. In general I would not recommend listening to alerts with this trust level as most likely this will not be a reliable result |

## Listening to events

Currently Staff++ supports 2 ways of being notified when an alt account is detected.

* The [alerting system](https://wiki.staffplusplus.org/master/features/alerts) (in-game)
* Through Discord ([Integration plugin](https://github.com/garagepoort/StaffPlusPlus/wiki/Discord-Integration))

## Whitelisting Accounts

Since some accounts might actually not be real alt accounts but still trigger the system, a whitelist is added to ensure that staff members can ignore these false positives.

The ignore a match you can use the `/altwhitelist` command.

* `/altwhitelist add playerName1 playerName2`
* `/altwhitelist remove playerName1 playerName2`
* `/altwhitelist list pagenumber` PageNumber is optional.

This will add or remove certain user combinations from the whitelist. When added to the whitelist this users combination will never trigger a detection event. Adding a combination to the whitelist tells the system that these 2 accounts are not alts.