3. A TCP server is running on a remote machine called sirius using "nc -lv 9090" (recall this command from the TCP chapter). This machine is on a planet outside the Solar system. An alien named Alice living on the Earth wants to communicate with the TCP server on sirius, but unfortunately, the Earth has a firewall that prevents all computers on the Earth from accessing any machine outside the Solar system. Alice does have a computer on Mars, which does not have such a restrict firewall rule. Alice's computer on Mars is called mars, and her account name is called alien. Please describe how Alice can use an SSH tunnel to bypass Earth's firewall, so she can talk to sirius.

(1) The port used in the local host machine should be 8080. Why not port 80? (check online)

(2) What command should Alice run to set up the SSH tunnel?

(3) Without the firewall, if Alice wants to communicate with the TCP server on sirius, she can use the "nc sirius 9090" command. Now, with the SSH tunnel and the firewall, what command should Alice run to access the server?