diff --git a/src/auth/auth_ldap.py b/src/auth/auth_ldap.py
index a0d42731..082cd6e3 100644
--- a/src/auth/auth_ldap.py
+++ b/src/auth/auth_ldap.py
@@ -85,6 +85,25 @@ def __init__(self, params_dict, temp_folder):
         else:
             self.username_template = None
 
+
+        username_attribute_pattern = strip(params_dict.get('username_attribute_pattern'))
+        if username_attribute_pattern:
+            self._username_attribute_pattern = username_attribute_pattern
+        else:
+            self._username_attribute_pattern = None
+
+        bind_dn = strip(params_dict.get('bind_dn'))
+        if bind_dn:
+            self._bind_dn = bind_dn
+        else:
+            self._bind_dn = None
+
+        bind_password = strip(params_dict.get('bind_password'))
+        if bind_password:
+            self._bind_passwd = bind_password
+        else:
+            self._bind_passwd = None
+
         base_dn = params_dict.get('base_dn')
         if base_dn:
             self._base_dn = base_dn.strip()
@@ -110,12 +129,78 @@ def authenticate(self, request_handler):
         username = request_handler.get_argument('username')
         password = request_handler.get_argument('password')
 
-        return self._authenticate_internal(username, password)
+        # If the following conditions, depending on config settings, are all met, 
+        # search for the dn by the given attribute.
+        if self._username_attribute_pattern and self._bind_dn and self._bind_passwd:
+            bind_connection = self._bind_user_connection(self._bind_dn, self._bind_passwd)
+            bind_dn = self._get_dn_from_user_attribute(bind_connection, username, self._username_attribute_pattern)
+            return self._authenticate_internal_by_bind(bind_dn, password, username)
+        else:
+            return self._authenticate_internal(username, password)
 
     def perform_basic_auth(self, user, password):
         self._authenticate_internal(user, password)
         return True
 
+    def _bind_user_connection(self, username, password):
+        LOGGER.info('Logging in bind-user ' + username)
+
+        try:
+            connection = self._connect(username, password)
+
+            if connection.bound:
+                LOGGER.info('bind-user ' + username + ' logged in')
+                return connection
+
+            error = connection.last_error
+
+        except Exception as e:
+            error = str(e)
+
+            if error not in KNOWN_REJECTIONS:
+                LOGGER.exception('Error occurred while ldap authentication of user ' + username)
+
+        if error in KNOWN_REJECTIONS:
+            LOGGER.info('Invalid credentials for user ' + username)
+            raise auth_base.AuthRejectedError('Invalid credentials')
+
+        raise auth_base.AuthFailureError(error)
+
+    # This method uses an additional parameter
+    def _authenticate_internal_by_bind(self, username, password, username_searched):
+        LOGGER.info('Logging in user ' + username)
+
+        try:
+            connection = self._connect(username, password)
+
+            if connection.bound:
+                try:
+                    user_dn, user_uid = self._get_user_ids(username, connection)
+                    LOGGER.debug('user ids: ' + str((user_dn, user_uid)))
+
+                    user_groups = self._fetch_user_groups(user_dn, user_uid, connection)
+                    LOGGER.info('Loaded groups for ' + username + ': ' + str(user_groups))
+                    self._set_user_groups(username_searched, user_groups)
+                except:
+                    LOGGER.exception('Failed to load groups for the user ' + username)
+
+                connection.unbind()
+                return username_searched
+
+            error = connection.last_error
+
+        except Exception as e:
+            error = str(e)
+
+            if error not in KNOWN_REJECTIONS:
+                LOGGER.exception('Error occurred while ldap authentication of user ' + username)
+
+        if error in KNOWN_REJECTIONS:
+            LOGGER.info('Invalid credentials for user ' + username)
+            raise auth_base.AuthRejectedError('Invalid credentials')
+
+        raise auth_base.AuthFailureError(error)
+
     def _authenticate_internal(self, username, password):
         LOGGER.info('Logging in user ' + username)
 
@@ -167,6 +252,20 @@ def _connect(self, full_username, password):
         connection.bind()
         return connection
 
+    def _get_dn_from_user_attribute(self, connection, value, attribute):
+        _attr_template = "(" + attribute + "=%s)"
+        search_request = SearchRequest(_attr_template, value)
+        entries = _search(self._base_dn, search_request, ['*'], connection)
+        if not entries:
+            return None
+
+        if len(entries) > 1:
+            logging.warning('More than one user found by filter: ' + str(search_request))
+            return None
+
+        entry = entries[0]
+        return get_entry_dn(entry)
+
     def _get_groups(self, user):
         groups = self._user_groups.get(user)
         if groups is not None:
@@ -236,6 +335,7 @@ def _set_user_groups(self, user, groups):
 
         new_groups_content = json.dumps(self._user_groups, indent=2)
         file_utils.write_file(self._groups_file, new_groups_content)
+        print('Gruppen', new_groups_content)
 
 
 class SearchRequest:
@@ -248,3 +348,5 @@ def as_search_string(self):
 
     def __str__(self) -> str:
         return self.as_search_string()
+
+