a) Explain how a firewall does address translation when it receives a TCP packet from a remote web server intended for a web client on the private network and the translation table contains the matching tuple needed for NAT.

b) Consider the Firewall Hole Punching mechanism from Module 4. Why is it necessary for both computers to send UDP packets to each other in the first place for the firewalls on both sides to permit traffic in both directions? Why can't Alice start sending UDP packets to Bob first, and then Bob reply to those packets?

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