Distinguish between packet-filtering firewalls and application-level gateways.

What will be an ideal response?

A packet-filtering firewall examines all data sent from outside a local area network and automatically rejects the data
packets that have local area network addresses. For example, if a hacker from outside obtains an address from a computer
inside the network and tries to sneak a harmful data packet through the firewall, the packet-filtering firewall will reject the
data packet since it originated outside the network but had an internal address. An application-level gateway scans the actual
data. If the message is deemed safe, it is allowed through the firewall.