Firewalls are devices, or really architectures, that protect information assets at a network perimeter. Firewalls provide a variety of technologies including:
- Packet filtering – permits or restricts incoming packets (information) based on the (a) information submitted and (b) the destination sent. For example, firewalls will allow only web traffic to be sent to the web server.
- Stateful packet inspection (SPI) – permits inbound traffic based on whether it has responded to an outbound request. In other words, an inbound web response from a website will only be allowed if the firewall links it to an outbound web request.
- Proxy serving – in this technology, the firewall acts on behalf of or “proxies” for a client. The client initiates a session with an outside server (e.g. a web server) but the proxy intercepts the request and separately presents the request to that server. If a server contained malicious or attack programs (malware), then that malware would actually attack the firewall appliance itself rather than the client. Given that the firewall is a hardened, i.e., a protected and strictly secured device, the attack would prove ineffective and the client (e.g. web browser) would be unscathed.
Firewalls also refer to types of architectures where hosts (i.e. servers providing services over the internet, a.k.a. bastion hosts) reside in a protected network called a demilitarized zone (DMZ). The assumption is that any host directly reachable from the internet will inevitably be compromised. As such, potentially compromised hosts (isolated in the DMZ network) can only initiate limited communication with systems in the internal (trusted) network, and therefore attacks from the DMZ have a lower likelihood of success.
Some firewalls may also provide other capabilities, which may or may not fall under the strict definition of “firewall.”
The Why: Our lightweight browser extension, Torus, acts similar to a firewall to protect your system from internet threats. Active whenever you browse the internet, Torus will block malicious or suspicious files from being downloaded onto your computer, whether it’s from an email, an ad, or a faulty link.