As you have seen, attackers can perform network reconnaissance or footprint your network in many different ways. We have purposely limited our discussion to common tools and techniques. Bear in mind, however, that new tools are released daily. Moreover, we chose a simplistic example to illustrate the concepts of footprinting. Often you will be faced with a daunting task of trying to identify and footprint tens or hundreds of domains. Therefore, we prefer to automate as many tasks as possible via a combination of shell and expect scripts or Perl programs. In addition, many attackers are well schooled in performing network reconnaissance activities without ever being discovered , and they are suitably equipped. Therefore, it is important to remember to minimize the amount and types of information leaked by your Internet presence and to implement vigilant monitoring.