A firewall helps protect networks and devices by controlling which network traffic may pass. This lesson introduces what firewalls do, how the idea developed, and where firewalls are deployed.
A firewall is a network security system that monitors and controls incoming and outgoing traffic according to configurable security rules. It creates a barrier between networks with different trust levels, such as a private company network and the public Internet. It can also control traffic between internal network segments, including VLANs.
All flashcards
What is a firewall?
A security system that monitors and controls incoming, outgoing, or inter-network traffic according to configurable rules.
What does a network-based firewall protect?
It controls traffic passing between networks, often protecting a LAN from a WAN such as the Internet.
What does a host-based firewall protect?
It runs on an individual host and controls that device's network traffic or access to its computing resources.
Why were routers considered firewall predecessors?
Routers segregated networks and could filter packets crossing between them, providing an early form of traffic control.
What was significant about the PIX Firewall?
It was an early commercial firewall and NAT product developed by Network Translation Inc.; Cisco later acquired the company.
Quiz questions
Which information does a basic packet filter commonly use to make a rule decision?Answer: Source and destination addresses, protocol, and port numbers.
What does connection tracking add to packet filtering?Answer: It maintains information about active conversations so packets can be evaluated in context.
How can application-layer inspection help when a protocol uses a non-standard port?Answer: It can recognize the protocol or application instead of relying only on the port number.
What can an endpoint-specific application firewall use to apply rules to a local process?Answer: The process ID associated with the application involved in the connection.
What does User ID enable a firewall policy to do?Answer: Apply rules based on identified users or groups rather than only fixed addresses.