Question

A packet filtering firewall operates at which of the following OSI layer?

• A. At the Application layer
• B. At the Transport Layer
• C. At the Network Layer
• D. Both 2 and 3

Answer 1

The correct option is D Both 2 and 3

A packet filtering firewall operates At the Transport Layer and At the Network Layer OSI layer.

Network layer or packet filters. Network layer firewalls, also called packet filters, operate at a relatively low level of the TCP/IP protocol stack, not allowing packets to pass through the firewall unless they match the established rule set. ... The term "packet filter" originated in the context of BSD operating systems.

These type of firewalls operate at Layer 3 and Layer 4 of the OSI model, which are the Network and Transport layers, respectively. They are simple in that it makes filtering decisions based on the header information of each packet. As a result, packet filter firewalls are not particularly flexible.

Packet Filtering Firewalls: Packet Filtering mechanisms work in the network layer of the OSI model. In packet filtering, each packet passing through a firewall is compared to a set of rules before it is allowed to pass through.