npm package: @jayv30/activedirectory2
Description: ActiveDirectory is an ldapjs client for authN (authentication) and authZ (authorization) for Microsoft Active Directory with range retrieval support for large Active Directory installations.
Author: Jay Karlsven
Latest version: 2.3.2

ActiveDirectory for Node
=========

> ## Module Maintenance Notice
> This module is minimally maintained. I, James Sumners, have not been in an
> environment where I need to communicate with an Active Directory server in
> over two years (as of this writing on 2020-08-25). Given that I do not need
> this module for my own work, it is not a priority for me. I will continue
> to review pull requests and issue releases as necessary, but to get the
> "best" support possible:
>
> 1. Read through the module's source code to learn how to either resolve
> your issue or to point out where the issue is.
> 2. Open a Pull Request to fix the issue if you are able. If you're not able,
> you should state _why_ in any issue you open.
> 3. Provide a thorough replication of your problem if you are opening an issue
> and not a Pull Request.
>
> If you rely on this module, it would be a great idea to start contributing
> your own Pull Requests to resolve open issues or any issues you have
> encountered. If I determine that you would be a good steward of the project,
> I will invite you to take up full maintenance of it.

ActiveDirectory is an ldapjs client for authN (authentication) and authZ (authorization) for Microsoft Active Directory with range retrieval support for large Active Directory installations. This code was a port of an existing C# library (not published) that I had written a few years ago. Here are the key features

  - Authenticate
  - Authorization (via group membership information)
  - Nested groups support
  - Range specifier / retrieval support (http://msdn.microsoft.com/en-us/library/dd358433.aspx)
  - Automatic paging support (Active Directory results (MaxPageSize) limited to 1000 per request by default)
  - Recycle bin (tombstone) query support
  - Referral support

Installation
--------------

```sh
npm install activedirectory2
```

Usage
--------------

```js
var ActiveDirectory = require('activedirectory2');
var config = { url: 'ldap://dc.domain.com',
               baseDN: 'dc=domain,dc=com',
               username: 'username@domain.com',
               password: 'password' }
var ad = new ActiveDirectory(config);
```

The username and password specified in the configuration are what are used for
user and group lookup operations.

Documentation
--------------
+ [Constructor](#constructor)
+ [authenticate](#authenticate)
+ [isUserMemberOf](#isUserMemberOf)
+ [find](#find)
+ [findUser](#findUser)
+ [findGroup](#findGroup)
+ [findUsers](#findUsers)
+ [findGroups](#findGroups)
+ [groupExists](#groupExists)
+ [userExists](#userExists)
+ [getGroupMembershipForGroup](#getGroupMembershipForGroup)
+ [getGroupMembershipForUser](#getGroupMembershipForUser)
+ [getUsersForGroup](#getUsersForGroup)
+ [getRootDSE](#getRootDSE)
+ [findDeletedObjects](#findDeletedObjects)
+ [options](#opts)

A Promise wrapper is available for all methods by an alternate `require`
statement:

```javascript
const AD = require('activedirectory2').promiseWrapper;
const config = { url: 'ldap://dc.domain.com',
               baseDN: 'dc=domain,dc=com',
               username: 'username@domain.com',
               password: 'password' }
const ad = new AD(config);
````

---------------------------------------

<a id="constructor"></a>
### ActiveDirectory(options)

Returns a new instance of the client configured according to the options object.

Options:

+ `url` {string}: Active Directory server to connect to, e.g. `ldap://ad.example.com`.
+ `baseDN` {string}: The root DN from which all searches will be performed, e.g. `dc=example,dc=com`.
+ `username` {string}: An account name capbable of performing the operations desired.
+ `password` {string}: Password for the given `username`.
+ `pageSize` {integer}: Number of results for each page in a paged search. Default: `1000`.
+ `entryParser` {function}: A function that will be invoked to parse each search entry.
  Signature: `function entryParser (entry, raw, callback) {}`. Optional.
+ `referrals` {object}: Specifies if referrals should be followed, and which to exclude
  if so. Default:

  ```
  {
    enabled: false,
    exclude: [
      'ldaps?://ForestDnsZones\\..*/.*',
      'ldaps?://DomainDnsZones\\..*/.*',
      'ldaps?://.*/CN=Configuration,.*'
    ]
  }
  ```
+ `attributes` {object}: Specifies which attributes to return for "user" or "group"
  searches. Default:

  ```
  {
    user: [
      'dn', 'distinguishedName',
      'userPrincipalName', 'sAMAccountName', 'mail',
      'lockoutTime', 'whenCreated', 'pwdLastSet', 'userAccountControl',
      'employeeID', 'sn', 'givenName', 'initials', 'cn', 'displayName',
      'comment', 'description'
    ],
    group: [
      'dn', 'cn', 'description', 'distinguishedName', 'objectCategory'
    ]
  }
  ```

Any additional keys on the options object will be parsed to find
[ldapjs options](http://ldapjs.org/client.html). The list of options
`activedirectory2` parses as ldapjs options is:

+ url
+ host
+ port
+ secure
+ tlsOptions
+ socketPath
+ log
+ timeout
+ idleTimeout
+ reconnect
+ queue
+ queueSize
+ queueTimeout
+ queueDisable
+ bindDN (Default: `username`)
+ bindCredentials (Default: `password`)
+ connectTimeout
+ tlsOptions
+ strictDN
+ paged

---------------------------------------

<a id="authenticate"></a>
### authenticate(username, password, callback)

Authenticates the username and password by doing a simple bind with the specified credentials.

__Arguments__

* username - The username to authenticate.
* password - The password to use for authentication.
* callback(err, authenticated) - A callback which is called after authentication is completed.

__Example__

```js
var ad = new ActiveDirectory(config);
var username = 'john.smith@domain.com';
var password = 'password';

ad.authenticate(username, password, function(err, auth) {
  if (err) {
    console.log('ERROR: '+JSON.stringify(err));
    return;
  }

  if (auth) {
    console.log('Authenticated!');
  }
  else {
    console.log('Authentication failed!');
  }
});
```

---------------------------------------

<a id="isUserMemberOf"></a>
### isUserMemberOf(opts, username, groupName, callback)

Checks to see if a user is a member of the specified group. This function will also check for group membership inside of a group.  Even if a user is not explicity listed as a member of a particular group, if a group that the user is a member of belongs to the group, then this function will return true.

__Arguments__
* opts - Optional parameters to extend or override functionality. See [optional parameters](#opts).
* username - The username to check for membership. Can be specied as a sAMAccountName, userPrincipalName or distinguishedName (dn)
* groupName - The group to check for membership. Can be a commonName (cn) or a distinguishedName (dn)
* callback - The callback to execute when completed. callback(err: {Object}, result: {Boolean})

__Example__

```js
var username = 'user@domain.com';
var groupName = 'Employees';

var ad = new ActiveDirectory(config);
var ad.isUserMemberOf(username, groupName, function(err, isMember) {
  if (err) {
    console.log('ERROR: ' +JSON.stringify(err));
    return;
  }

  console.log(username + ' isMemberOf ' + groupName + ': ' + isMember);
});
```

---------------------------------------

<a id="groupExists"></a>
### groupExists(opts, groupName, callback)

Checks to see if the specified group exists.

__Arguments__
* opts - Optional parameters to extend or override functionality. See [optional parameters](#opts).
* groupName - The group to check if is defined. Can be a commonName (cn) or a distinguishedName (dn)
* callback - The callback to execute when completed. callback(err: {Object}, result: {Boolean})

__Example__

```js
var groupName = 'Employees';

var ad = new ActiveDirectory(config);
ad.groupExists(groupName, function(err, exists) {
  if (err) {
    console.log('ERROR: ' +JSON.stringify(err));
    return;
  }

  console.log(groupName + ' exists: ' + exists);
});
```

---------------------------------------

<a id="userExists"></a>
### userExists(opts, username, callback)

Checks to see if the specified user exists.

__Arguments__
* opts - Optional parameters to extend or override functionality. See [optional parameters](#opts).
* username - The username to check if it exists. Can be a sAMAccountName, userPrincipalName or a distinguishedName (dn)
* callback - The callback to execute when completed. callback(err: {Object}, result: {Boolean})

__Example__

```js
var username = 'john.smith@domain.com';

var ad = new ActiveDirectory(config);
ad.userExists(username, function(err, exists) {
  if (err) {
    console.log('ERROR: ' +JSON.stringify(err));
    return;
  }

  console.log(username + ' exists: ' + exists);
});
```

---------------------------------------

<a id="getUsersForGroup"></a>
### getUsersForGroup(opts, groupName, callback)

For the specified group, retrieve all of the users that belong to the group. If the group contains groups, then the members of those groups are recursively retrieved as well to build a complete list of users that belong to the specified group.

__Arguments__
* opts - Optional parameters to extend or override functionality. See [optional parameters](#opts).
* groupName - The name of the group to retrieve membership from. Can be a commonName (cn) or a distinguishedName (dn)
* callback - The callback to execute when completed. callback(err: {Object}, groups: {Array[User]})

__Example__

```js
var groupName = 'Employees';

var ad = new ActiveDirectory(config);
ad.getUsersForGroup(groupName, function(err, users) {
  if (err) {
    console.log('ERROR: ' +JSON.stringify(err));
    return;
  }

  if (! users) console.log('Group: ' + groupName + ' not found.');
  else {
    console.log(JSON.stringify(users));
  }
});
```


---------------------------------------

<a id="getGroupMembershipForUser"></a>
### getGroupMembershipForUser(opts, username, callback)

For the specified username, retrieve all of the groups that a user belongs to. If a retrieved group is a member of another group, then that group is recursively retrieved as well to build a complete hierarchy of groups that a user belongs to.

__Arguments__
* opts - Optional parameters to extend or override functionality. See [optional parameters](#opts).
* username - The name of the user to retrieve group membership for. Can be a sAMAccountName, userPrincipalName, or a distinguishedName (dn)
* callback - The callback to execute when completed. callback(err: {Object}, groups: {Array[Group]})

__Example__

```js
var sAMAccountName = 'john.smith@domain.com';

var ad = new ActiveDirectory(config);
ad.getGroupMembershipForUser(sAMAccountName, function(err, groups) {
  if (err) {
    console.log('ERROR: ' +JSON.stringify(err));
    return;
  }

  if (! groups) console.log('User: ' + sAMAccountName + ' not found.');
  else console.log(JSON.stringify(groups));
});
```

---------------------------------------

<a id="getGroupMembershipForGroup"></a>
### getGroupMembershipForGroup(opts, groupName, callback)

For the specified group, retrieve all of the groups that the group is a member of. If a retrieved group is a member of another group, then that group is recursively retrieved as well to build a complete hierarchy of groups that a user belongs to.

__Arguments__
* opts - Optional parameters to extend or override functionality. See [optional parameters](#opts).
* groupName - The name of the user to retrieve group membership for. Can be a sAMAccountName, userPrincipalName, or a distinguishedName (dn)
* callback - The callback to execute when completed. callback(err: {Object}, groups: {Array[Group]})

__Example__

```js
var groupName = 'Employees';

var ad = new ActiveDirectory(config);
ad.getGroupMembershipForGroup(groupName, function(err, groups) {
  if (err) {
    console.log('ERROR: ' +JSON.stringify(err));
    return;
  }

  if (! groups) console.log('Group: ' + groupName + ' not found.');
  else console.log(JSON.stringify(groups));
});
```

---------------------------------------

<a id="find"></a>
### find(opts, callback)

Perform a generic search for the specified LDAP query filter. This function will return both
groups and users that match the specified filter. Any results not recognized as a user or group
(i.e. computer accounts, etc.) can be found in the 'other' attribute / array of the result.

__Arguments__
* opts - Optional parameters to extend or override functionality. See [optional parameters](#opts). If only a string is provided, then the string is assumed to be an LDAP filter
* callback - The callback to execute when completed. callback(err: {Object}, groups: {Array[Group]})

__Example__

```js
var _ = require('underscore');
var query = 'cn=*Exchange*';
var opts = {
  includeMembership : [ 'group', 'user' ], // Optionally can use 'all'
  includeDeleted : false
};

var ad = new ActiveDirectory(config);
ad.find(query, function(err, results) {
  if ((err) || (! results)) {
    console.log('ERROR: ' + JSON.stringify(err));
    return;
  }

  console.log('Groups');
  _.each(results.groups, function(group) {
    console.log('  ' + group.cn);
  });

  console.log('Users');
  _.each(results.users, function(user) {
    console.log('  ' + user.cn);
  });

  console.log('Other');
  _.each(results.other, function(other) {
    console.log('  ' + other.cn);
  });
});
```

---------------------------------------

<a id="findDeletedObjects"></a>
### findDeletedObjects(opts, callback)

If tombstoning (recycle bin) is enabled for the Active Directory installation, use findDeletedObjects to retrieve
items in the recycle bin.

More information about tombstoning and enabling can be found at:

* [Enable the Active Directory Recycle Bin (and other New Features)](http://technet.microsoft.com/en-us/magazine/ff793473.aspx)
* [Reanimating Active Directory Tombstone Objects](http://technet.microsoft.com/en-us/magazine/2007.09.tombstones.aspx)

Note: That when an LDAP entry / object is tombstoned, not all attributes for that item are retained.
This is a limitation of Active Directory itself and not the library itself.

__Arguments__
* opts - Optional parameters to extend or override functionality. See [optional parameters](#opts). If only a string is provided, then the string is assumed to be an LDAP filter
* callback - The callback to execute when completed. callback(err: {Object}, result: {Array})

If the baseDN is not specified, then a RootDSE query will be performed on the attached URL and 'ou-Deleted Objects'
will be appended.

__Example__

```js
var url = 'ldap://yourdomain.com';
var opts = {
  baseDN: 'ou=Deleted Objects, dc=yourdomain, dc=com',
  filter: 'cn=*Bob*'
};
ad.findDeletedObjects(opts, function(err, result) {
  if (err) {
    console.log('ERROR: ' +JSON.stringify(err));
    return;
  }

  console.log('findDeletedObjects: '+JSON.stringify(result));
});
```

---------------------------------------

<a id="findUser"></a>
### findUser(opts, username, callback)

Looks up or finds a username by their sAMAccountName, userPrincipalName, distinguishedName (dn) or custom filter. If found, the returned object contains all of the requested attributes. By default, the following attributes are returned:

* userPrincipalName, sAMAccountName, mail, lockoutTime, whenCreated, pwdLastSet, userAccountControl, employeeID,  sn,  givenName, initials, cn, displayName, comment, description

__Arguments__

* opts - Optional parameters to extend or override functionality. See [optional parameters](#opts).
* username - The username to retrieve information about. Optionally can pass in the distinguishedName (dn) of the user to retrieve.
* callback(err, user) - The callback to execute when completed. callback(err: {Object}, user: {User})

__Example__

```js
// Any of the following username types can be searched on
var sAMAccountName = 'username';
var userPrincipalName = 'username@domain.com';
var dn = 'CN=Smith\\, John,OU=Users,DC=domain,DC=com';

// Find user by a sAMAccountName
var ad = new ActiveDirectory(config);
ad.findUser(sAMAccountName, function(err, user) {
  if (err) {
    console.log('ERROR: ' +JSON.stringify(err));
    return;
  }

  if (! user) console.log('User: ' + sAMAccountName + ' not found.');
  else console.log(JSON.stringify(user));
});
```

---------------------------------------

<a id="findUsers"></a>
### findUsers(opts, callback)

Perform a generic search for users that match the specified filter. The default LDAP filter for users is
specified as (&(|(objectClass=user)(objectClass=person))(!(objectClass=computer))(!(objectClass=group)))

__Arguments__
* opts - Optional parameters to extend or override functionality. See [optional parameters](#opts). If only a string is provided, then the string is assumed to be an LDAP filter that will be appended as the last parameter in the default LDAP filter.
* callback - The callback to execute when completed. callback(err: {Object}, users: {Array[User]})

__Example__

```js
var query = 'cn=*George*';

var ad = new ActiveDirectory(config);
ad.findUsers(query, true, function(err, users) {
  if (err) {
    console.log('ERROR: ' +JSON.stringify(err));
    return;
  }

  if ((! users) || (users.length == 0)) console.log('No users found.');
  else {
    console.log('findUsers: '+JSON.stringify(users));
  }
});
```

---------------------------------------

<a id="findGroup"></a>
### findGroup(opts, groupName, callback)

Looks up or find a group by common name (CN) which is required to be unique in Active Directory or optionally by the distinguished name. Supports groups with range retrieval specifiers. The following attributes are returned by default for the group:

* objectCategory, distinguishedName, cn, description, member

__Arguments__

* opts - Optional parameters to extend or override functionality. See [optional parameters](#opts).
* groupName -  The group (cn) to retrieve information about. Optionally can pass in the distinguishedName (dn) of the group to retrieve.
* callback(err, group) - The callback to execute when completed. callback(err: {Object}, group: {Group})


__Example__

```js
// Any of the following group names can be searched on
var groupName = 'Employees';
var dn = 'CN=Employees,OU=Groups,DC=domain,DC=com'

// Find group by common name
var ad = new ActiveDirectory(config);
ad.findGroup(groupName, function(err, group) {
  if (err) {
    console.log('ERROR: ' +JSON.stringify(err));
    return;
  }

  if (! user) console.log('Group: ' + groupName + ' not found.');
  else {
    console.log(group);
    console.log('Members: ' + (group.member || []).length);
  }
});
```

---------------------------------------

<a id="findGroups"></a>
### findGroups(opts, callback)

Perform a generic search for groups that match the specified filter. The default LDAP filter for groups is
specified as (&(objectClass=group)(!(objectClass=computer))(!(objectClass=user))(!(objectClass=person)))

__Arguments__
* opts - Optional parameters to extend or override functionality. See [optional parameters](#opts). If only a string is provided, then the string is assumed to be an LDAP filter that will be appended as the last parameter in the default LDAP filter.
* callback - The callback to execute when completed. callback(err: {Object}, groups: {Array[Group]})

__Example__

```js
var query = 'CN=*Admin*';

var ad = new ActiveDirectory(config);
ad.findGroups(query, function(err, groups) {
  if (err) {
    console.log('ERROR: ' +JSON.stringify(err));
    return;
  }

  if ((! groups) || (groups.length == 0)) console.log('No groups found.');
  else {
    console.log('findGroups: '+JSON.stringify(groups));
  }
});
```

---------------------------------------

<a id="getRootDSE"></a>
### getRootDSE(url, attributes, callback)

Retrieves the root DSE for the specified url. Can be called statically.

__Arguments__
* url - The url to retrieve the root DSE for.
* attributes - The optional list of attributes to retrieve. Returns all if not specified.
* callback - The callback to execute when completed. callback(err: {Object}, result: {Object})

__Example__

```js
var url = 'ldap://yourdomain.com';
ActiveDirectory.prototype.getRootDSE(url, [ 'defaultNamingContext' ], function(err, result) {
  if (err) {
    console.log('ERROR: ' +JSON.stringify(err));
    return;
  }

  console.log('getRootDSE: '+JSON.stringify(result));
});

// Or can be called with an instance...
var ad = new ActiveDirectory(config);
ad.getRootDSE(function(err, result) {
  //...
});
```

---------------------------------------
## Advanced Usage

### Attributes

By default, the following attributes are returned for users and groups:

* user - distinguishedName, userPrincipalName, sAMAccountName, mail, lockoutTime, whenCreated, pwdLastSet, userAccountControl, employeeID,  sn,  givenName, initials, cn, displayName, comment, description
* group - distinguishedName, objectCategory, cn, description

If you need to override those defaults, then you can override them when you create your ActiveDirectory instance:

```js
var ad = new ActiveDirectory({ url: 'ldap://dc.domain.com',
                               baseDN: 'dc=domain,dc=com',
                               username: 'username@domain.com',
                               password: 'password',
                               attributes: {
                                 user: [ 'myCustomAttribute', 'mail', 'userPrinicipalName' ],
                                 group: [ 'anotherCustomAttribute', 'objectCategory' ]
                               }
                              });
```

If overriding the 'user' or 'group' attribute, you must specify ALL of the attributes you want. The existing defaults
will be overridden. Optionally, you can override the attributes on a per call basis using the 'opts' parameter.

### Referrals

By default, referral chasing is disabled. To enable it, specify a referrals attribute when you create your instance.
The referrals object has the following syntax:

```js
{
  referrals: {
    enabled: false,
    excluded: [
      'ldaps?://ForestDnsZones\./.*',
      'ldaps?://DomainDnsZones\./.*',
      'ldaps?://.*/CN=Configuration,.*'
    ]
  }
}
```

The 'excluded' options is a list of regular expression filters to ignore specific referrals. The default exclusion list
is included above, ignoring the special partitions that ActiveDirectory creates by default. To specify these options,
override them as follows:

```js
var ad = new ActiveDirectory({ url: 'ldap://dc.domain.com',
                               baseDN: 'dc=domain,dc=com',
                               username: 'username@domain.com',
                               password: 'password',
                               attributes: { ... },
                               referrals: {
                                 enabled: true,
                                 excluded: [ ]
                               }
                              });
```

If you enable referral chasing, the specified username MUST be a userPrincipalName.

### Custom Entry Parsing

if you want to manipulate the search entry in a different way or perhaps augment the search
result with additional data, you can pass a custom parser. This is useful, for example, in case
you want to change the objectSid or GUID which are binary values.

Example:

```js
function customEntryParser(entry, raw, callback){
    if (raw.hasOwnProperty("objectSid")){
        entry.objectSid = raw.objectSid;
    }
    if (raw.hasOwnProperty("objectGUID")){
        entry.objectGUID = raw.objectGUID;
    }
    callback(entry);
};
```

If you want to specify your own parser you can override the default parser as follows:

```js
var ad = new ActiveDirectory({ url: 'ldap://dc.domain.com',
                               baseDN: 'dc=domain,dc=com',
                               username: 'username@domain.com',
                               password: 'password',
                               attributes: { ... },
                               referrals: { ... },
                               entryParser : customEntryParser
                              });
```

Optionally, you can specify your custom entry parser as part of the 'opts' object. See [optional parameters](#opts)
for more information.

```js
var opts = function(entry, raw, callback) {
  entry.retrievedAt = new Date();
  callback(entry);
};
ad.findUser(opts, 'userPrincipalName=bob@domain.com', function(err, user) {
 ...
});
```

<a id="opts"></a>
### Optional Parameters / Extended Functionality

Any method which takes an `opts` parameter allows for additional options. Options
for both `activedirectory2` and the internal ldapjs client are supported.

Currently supported ldapjs options are:

+ `url` - a valid LDAP url.
+ `tlsOptions` - additional tls options (see ldapjs for more information).
+ `socketPath` - if you're running an LDAP server over a Unix Domain Socket, use this.
+ `log` - a logger instance that conforms to ldapjs's logger requirements.
+ `timeout` - how long in milliseconds the client should let operations live for before timing out.
  Default is Infinity.
+ `idleTimeout` - how long the client should wait before timing out on TCP connections.
  Default is up to the OS.
+ `connectTimeout` - milliseconds client should wait before timing out on TCP connections. Default is OS default.
+ `strictDN` - force strict DN parsing for client methods. Default is true.

`activedirectory2` specific options are:

+ `baseDN` - The alternative baseDN to use than the one specified in the ctor.
+ `bindDN` - The DN all connections should be bound as.
+ `bindCredentials` - The credentials to use with bindDN.
+ `scope` - One of base, one, or sub. Defaults to base.
+ `filter` - A string version of an LDAP filter (see below), or a
  programatically constructed Filter object. Defaults to (objectclass=+).
+ `attributes` - attributes to select and return (if these are set, the server
  will return only these attributes). Defaults to the empty set, which means all attributes.
+ `sizeLimit` - the maximum number of entries to return. Defaults to 0 (unlimited).
+ `timeLimit` - the maximum amount of time the server should take in responding,
  in seconds. Defaults to 10. Lots of servers will ignore this.
+ `includeMembership` - Indicates that a search or find operation should enumerate
  the group memberships of the specified result types. Supported values are [ 'user', 'group', 'all' ].
+ `includeDeleted` - Indicates that results should include tombstoned / deleted
  items. Please see [findDeletedObject](#findDeletedObjects) for additional notes and caveats.
+ `entryParser` - Allows for a custom function to be specified for parsing of the
  resulting ldap object. Examples include augmenting ldap data with external data
  from an RDBMs. `function onParse(entry, raw, callback) { callback(entry); }`
  If null is returned, the result is excluded.
+ `logging` - A logger that conforms to the [abstract-logging][abstract-logging]
  interface. The library logs all messages at the "trace" level.

  ```js
  const pino = require('pino')
  const pretty = pino.pretty()
  pretty.pipe(process.stdout)
  const log = pino({level: 'trace'}, pretty)
  const ad = new ActiveDirectory({logging: log})
  ```

[abstract-logging]: https://www.npmjs.com/package/abstract-logging

#### Example

```js
var opts = {
  scope: 'sub',
  filter: 'objectClass=User',
  includeMembership: [ 'user' ],
  entryParser: function(entry, raw, callback) {
    // returning null with exclude result
    if (entry.ignore) return(null);

    entry.retrievedAt = new Date();
    entry.preferredServer = getPreferredServerFromDatabase(entry.userPrincipalName);

    callback(entry);
  }
};
```

------------------------------------------------

  [underscore]: http://underscorejs.org/
  [async]: https://github.com/caolan/async
  [ldapjs]: http://ldapjs.org/