What is a Firewall?

A firewall is a crucial network security device that monitors incoming and outgoing traffic according to a defined set of security rules. Firewalls create a barrier between internal networks and unsecured external networks like the public Internet.

Why are Firewalls Important?

According to a 2022 survey, over 30% of organizations experienced a cyberattack that penetrated their networks in the past year. Properly configured firewalls are an essential line of defense against common attacks like malware, ransomware, phishing scams, denial of service attacks and more.

Firewalls block unauthorized access, acting as a traffic cop only allowing approved connections. For example, a firewall could be configured to:

  • Allow email traffic from designated servers
  • Block malicious domains known for cyberattacks
  • Only permit remote access to authorized users

Without a firewall, internal networks have no security mechanisms governing traffic that crosses their boundaries. This puts personal information, intellectual property, and critical infrastructure at major risk.

Firewall Architectures

There are several common types of firewall architectures:

Packet Filtering Firewalls

Packet filtering firewalls work by inspecting packets in data streams as they enter or exit the network. Simple rules determine whether traffic should be allowed or blocked based on factors like:

  • IP addresses – Allow or block specific addresses
  • Ports – Allow traffic only from permitted ports
  • Protocols – Block unsafe protocols

Packet filtering firewalls provide high performance but limited inspection capabilities for attacks that use allowed ports or protocols.

Proxy Server Firewalls

Proxy server firewalls act as an intermediary for network traffic, receiving and analyzing all requests through a single gateway point. No traffic is allowed directly from external networks to internal servers.

Proxy firewalls provide more scrutiny than packet filtering but have lower performance. Common proxies:

  • Web proxy for web traffic
  • Email proxy for email

And more for other services.

Stateful Inspection Firewalls

Stateful inspection firewalls filter packets similar to packet filtering but also monitor communication to determine context. This allows them to permit two-way sessions for protocols like FTP while blocking unsafe traffic.

They also provide better protection against attacks disguised as legitimate traffic by validating sequence numbers, requests, etc. Maintaining state does have some performance impact.

How to Bypass Firewalls

While firewalls provide excellent protections, you may occasionally encounter a website blocked by filters put in place by an organization, country, school or other institution. There are several methods to securely bypass firewall restrictions:

Use a VPN

A VPN or Virtual Private Network…

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