What is the purpose of a firewall on your computer?

Answer 1

Its primary function is to prevent accesses from untrusted (or undesired) external systems to internal systems and services, and to prevent internal users and systems to access external untrusted or undesired systems and services.

More generally, its purpose is to implement security and performance policies.

As an example, you can prevent external systems to access internal servers, as well as to prevent users to use P2P software or access social networks, for performance and security reasons.

Answer 2

A firewall is a device or set of devices designed to permit or deny network transmissions based upon a set of rules and is frequently used to protect networks from unauthorized access while permitting legitimate communications to pass.

Specific functions are:

• deny inbound connections from unauthorized sources
• control outbound connections from computers within the protected network to prevent connection to unauthorized outside nodes
• Through the use of enabled audit logs, track inbound and outbound connections
• Filter traffic based on packet contents. Packet filters act by inspecting the "packets" which represent the basic unit of data transfer between computers on the internet. If a packet matches the packet filter's set of rules, the packet filter will drop (silently discard) the packet, or reject it (discard it, and send "error responses" to the source).
• Second-generation firewalls, in addition to what first-generation look for, work up to layer 4 (transport layer) of the OSI model. Therefore they regard placement of each individual packet within the packet series. This technology is generally referred to as a stateful packet inspection as it maintains records of all connections passing through the firewall and is able to determine whether a packet is the start of a new connection, a part of an existing connection, or is an invalid packet. Though there is still a set of static rules in such a firewall, the state of a connection can itself be one of the criteria which trigger specific rules.
• Third generation firewalls can "understand" certain applications and protocols (such as File Transfer Protocol, DNS, or web browsing), and it can detect if an unwanted protocol is sneaking through on a non-standard port or if a protocol is being abused in any harmful way.
• Firewalls often have network address translation (NAT) functionality, and the hosts protected behind a firewall commonly have addresses in the "private address range", as defined in RFC 1918. Firewalls often have such functionality to hide the true address of protected hosts.

Answer 3

Its primary function is to prevent accesses from untrusted (or undesired) external systems to internal systems and services, and to prevent internal users and systems to access external untrusted or undesired systems and services.

More generally, its purpose is to implement security and performance policies.

As an example, you can prevent external systems to access internal servers, as well as to prevent users to use P2P software or access social networks, for performance and security reasons.

Answer 4

A firewall prevents unauthorised access to your computer over the internet. It stops people trying to access the programs and personal files on your hard-drive. A firewall isn't enough though - you should use a good anti-virus program in tandem with your firewall.

Answer 5

A firewall is for protecting your computer against a virus that could possibly disable or cause you to lose files on your computer.

Answer 6

The firewall protects your computer and block threats and attacks from getting into your computer and stealing information.

Answer 7

The purpose of the firewall is to defend against threats against the network.