code: public function bind($username, $password)
      {
          // Tries to run the LDAP Connection as TLS
          if ($this->tls) {
              if ( ! ldap_start_tls($this->connection)) {
                  throw new ConnectionException('Unable to Connect to LDAP using TLS.');
              }
          }
  
          try {
              $this->bound = ldap_bind($this->connection, $username, $password);
          } catch (ErrorException $e) {
              $this->bound = false;
          }
  
          return $this->bound;
      }
docs: Binds LDAP connection to the server
  
  @param $username
  @param $password
  
  @return bool
  
  @throws ConnectionException