Which firewall feature is used to ensure that packets coming into a network are legitimate responses to requests initiated from internal hosts?stateful packet inspectionapplication filteringURL filteringpacket filtering

To determine which firewall feature ensures that packets coming into a network are legitimate responses to requests initiated from internal hosts, let's analyze each option step by step:

1. Stateful Packet Inspection:

   • This feature keeps track of the state of active connections and makes decisions based on the context of the traffic. It ensures that incoming packets are part of an established connection initiated by an internal host.
   • Example: If an internal host requests a webpage, stateful packet inspection will allow the response from the web server to pass through the firewall because it recognizes the connection as legitimate.

2. Application Filtering:

   • This feature inspects the data within the packets to determine if they belong to a specific application. It can block or allow traffic based on the application type.
   • Example: Blocking or allowing traffic from applications like Skype, BitTorrent, etc.

3. URL Filtering:

   • This feature blocks or allows access to specific websites based on their URLs. It is often used to restrict access to certain web content.
   • Example: Preventing users from accessing social media sites during work hours.

4. Packet Filtering:

   • This feature inspects packets at a basic level, checking source and destination IP addresses, ports, and protocols. It does not keep track of the state of connections.
   • Example: Allowing or blocking traffic based on predefined rules, such as blocking all traffic from a specific IP address.

Given the descriptions, the feature that ensures packets coming into a network are legitimate responses to requests initiated from internal hosts is:

Stateful Packet Inspection

This is because stateful packet inspection tracks the state of active connections and ensures that incoming packets are part of an established connection, thus verifying their legitimacy.