a) Can a packet filter block all incoming email containing the phrase Make money fast? If yes, show a packet filtering ruleset that provides this functionality; if no, explain why a (stateless) packet filter cannot do it.

b) List and explain three network threats that a firewall does not protect against.

c) Youve been asked to protect a site with a firewall. There are no inbound services. The only outbound service is Web browsing, which of course requires some form of DNS name resolution. There is a lot of concern about people going to improper sites; there is also a desire to filter all web content to remove active content. Describe the best firewall configuration for this site. Justify the purpose of each element.

d) Which is generally safer between a firewall with a default deny policy or a firewall with a default allow policy? Why?