Which firewall type operates at the session layer (or transport layer) and forwards data between networks without verification, blocking inbound packets from the host but allowing traffic to pass through?

Which firewall type operates at the session layer (or transport layer) and forwards data between networks without verification, blocking inbound packets from the host but allowing traffic to pass through?

• A. Circuit-Level Gateway Firewall
• B. Packet Filtering Firewall
• C. Application-Level Proxy
• D. Network Address Translation

Answer: (B)

Packet filtering firewalls decide whether to allow or block traffic by looking at the packet headers, such as source/destination IP addresses and port numbers, rather than establishing or inspecting a connection. This stateless approach means they forward data between networks based on simple rules without verifying the content or session state. Because decisions are made per packet, inbound packets destined for internal hosts can be blocked by policy while other traffic is allowed to pass through. This makes them fast and straightforward at the transport (and sometimes network) layer, but they don’t perform deeper or session-aware verification. Circuit-level gateways, by contrast, operate at the session layer and establish a circuit before passing traffic, which involves some form of session verification. Application-level proxies inspect application data and enforce higher-level policies. NAT is a translation mechanism often used alongside firewalls, not a firewall type by itself.

Packet filtering firewalls decide whether to allow or block traffic by looking at the packet headers, such as source/destination IP addresses and port numbers, rather than establishing or inspecting a connection. This stateless approach means they forward data between networks based on simple rules without verifying the content or session state. Because decisions are made per packet, inbound packets destined for internal hosts can be blocked by policy while other traffic is allowed to pass through. This makes them fast and straightforward at the transport (and sometimes network) layer, but they don’t perform deeper or session-aware verification.

Circuit-level gateways, by contrast, operate at the session layer and establish a circuit before passing traffic, which involves some form of session verification. Application-level proxies inspect application data and enforce higher-level policies. NAT is a translation mechanism often used alongside firewalls, not a firewall type by itself.