Firewalls function as one or more of the following: packet filter, proxy, stateful inspection, and application firewall. Describe the concept of a...

Firewalls function as one or more of the following: packet filter, proxy, stateful inspection, and application firewall. Describe the concept of a packet filter. Discuss how you would create a rule for a packet filter firewall to block a port or a protocol. How would you test the rule? How would you test a stateful firewall's rules? What tools would you use? Explain application firewalls. Cite your resources.