A firewall is a network security device that acts as a barrier between a trusted internal network and untrusted external networks, like the internet. It monitors and filters incoming and outgoing network traffic based on predetermined security rules, allowing safe traffic while blocking malicious activity. Firewalls are a critical first line of defense against unauthorized access, cyberattacks, and malware.
How it works
- Acts as a gatekeeper: Firewalls inspect every data packet that passes through them, much like a security guard checking IDs at a building entrance.
- Uses predefined rules: They evaluate traffic against a set of rules to decide whether to allow or deny it.
- Blocks malicious traffic: They can prevent threats from entering a private network and can also stop sensitive data from leaving.
- Can be hardware or software: Firewalls can be dedicated hardware devices, software programs on an individual computer (host-based firewall), or a combination of both.
Types of firewalls
- Network-based: These are hardware appliances placed at the border of a network to protect all devices on it.
- Host-based: These are software programs installed on individual computers or servers to protect just that specific device.
