What is a Firewall?
A firewall is a network security device that monitors incoming and outgoing network traffic and allows or blocks data packets based on security rules. The purpose of the firewall is to act as your own personal bodyguard that checks incoming traffic from external sources in order to block malicious traffic like viruses and hackers.
What Firewalls Do?
Basically, firewalls need to be able to perform the following tasks:
- Defend resources
- Validate access
- Manage and control network traffic
- Record and report on events
- Act as an intermediary.
How does a firewall work?
Firewalls carefully analyze incoming traffic based on pre-configured rules and filter traffic coming from unsecured or suspicious sources to prevent attacks.
Think of IP addresses as houses, and port numbers as rooms within the house. Only trusted people (source addresses) are allowed to enter the house (destination address) at all—then it’s further filtered so that people within the house are only allowed to access certain rooms (destination ports), depending on if they’re the owner, a child, or a guest. The owner is allowed access to any room (any port), while children and guests are allowed into a certain set of rooms (specific ports).
A firewall is important when
- You surf the internet.
- You connect to the internet via a public network.
- You run a network which needs to be kept isolated from the internet
- Most Firewalls are highly configurable so you can easily create security policies to suit your individual needs.
Types of firewalls
Firewalls can either be software or hardware, though it’s best to have both. A software firewall is a program installed on each computer and regulates traffic through port numbers and applications, while a physical firewall is a piece of equipment installed between your network and gateway.