170 Chapter 10 FirewallsNN47922-500• The firewall uses session filtering, or smart rules, that enhance the filteringprocess and control the network session rather than control individual packetsin a session.• The firewall provides e-mail service to notify you of routine reports and whenalerts occur.When to use the firewall1 To prevent DoS attacks and prevent hackers cracking your network.2 A range of source and destination IP addresses as well as port numbers can bespecified within one firewall rule, making the firewall a better choice whencomplex rules are required.3 To selectively block or allow inbound or outbound traffic between inside hostor networks and outside host or networks. Remember that filters cannotdistinguish traffic originating from an inside host or an outside host by IPaddress.4 The firewall performs better than filtering if you need to check many rules.5 Use the firewall if you need routine e-mail reports about your system or needto be alerted when attacks occur.6 The firewall can block any specific URL traffic that occurs in the future. TheURL can be saved in an Access Control List (ACL) database.
