System Security

Alice, Bob and Mallory are all on a local network. Mallory is an off-path attacker with a super-fast connection: her packets always arrive first.

Assume Mallory knows the MAC and IP addresses of Alice and Bob's computers. Assume that Alice will accept the first valid packet she receives as coming from Bob, and ignore what happens once Bob's real packet arrives.

1. Alice and Bob are communicating through UDP on some unknown ports. What does Mallory need to guess to insert a fake UDP datagram from Bob to Alice?
2. Alice and Bob are communicating through TCP on some unknown ports. What does Mallory need to guess to insert a fake TCP packet from Bob to Alice?
3. Alice is about to send a DNS request to Bob's resolver for 1.2.3.4.5.6.7.com. What does Mallory need to guess to spoof the reply? (
4. Alice is about to send an ARP request for Bob's MAC address. What does Mallory need to guess to spoof the reply?
5. If Mallory was on-path, could she spoof all of the above responses with a 100% success rate.