Firewall types
Packet Filtering Firewall: They are usually part of a router and each packet is compared to a set of criteria before it is forwarded, dropped, or a message is sent to the originator.
- Circuit level Gateway: they monitor TCP handshaking between packets to determine whether a requested session is legitimate. Information passed to remote computer through a circuit level gateway appears to have originated from the gateway. On the other hand, they do not filter individual packets.