What does

a firewall check to prevent particular ports and applications from getting packets into an organization?

A. Transport layer port numbers and application layer headers

B. Presentation layer headers and the session layer port numbers

C. Network layer header

s and the session layer port numbers

D. Application layer port numbers and the transport layer headers

Newer firewalls can filter traffic based on many packet attributes like source IP address, source port, destination IP address or transport la

yer port, destination service like WWW or FTP. They can filter based on protocols, TTL values, netblock of originator, of the source, and many other attributes.

Application layer firewalls are responsible for filtering at 3, 4, 5, 7 layer. Because they ana

lyze the application layer headers, most firewall control and filtering is performed actually in the software.

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