|  |  | Some firewalls display banners that describe themselves when you connect directly to them. This information can be found simply by connecting to the telnet port. Often ports like ftp and SMTP will offer the hacker some information as well. Countermeasures: limit the amount of information offered by your banners add a legal statement about the authorized use of the systems Sometimes just a warning will encourage a hacker to attack another network that is less protected than yours.