A firewall is simply a program or hardware device that filters the information coming through the internet connection or computer system. It filters the incoming and outgoing network traffic using some pre determined criteria.

Thus, a firewall forms a barrier through which the traffic going in each direction must pass. The firewall’s security policy dictates which traffic is authorized to pass in each direction.

Service Control: Determines the types of internet services that can be accessed, inbound or outbound. The firewall may filter traffic on the basis of IP address, protocol, or port number; may provide proxy software that receives and interprets each service request before passing it on; or may host the server software itself, such as a web or mail service.

Direction Control: Determines the direction in which a particular service requests may be initiated and allowed to flow through the firewall.
Firewalls generally use two or more of the following methods:

  • Packet filtering 
  • Application gateway 
  • Circuit level gateway 
  • Proxy servers 
  • Stateful inspection or Dynamic packet filtering 

Firewalls are generally categorized as network-based or host-based. 

Network Layer Firewalls: Also called packet filters, operate at a relatively low level of the TCP/ IP protocol stack, not allowing packets to pass through the firewall unless they match the established rule set. 

Application Layer Firewalls: They work on the application level of the TCP/ IP stack (i.e., all the browser traffic, or all the telnet or FTP traffic), and may intercept all the packets traveling to or from an application.

In nutshell, a firewall: 

  • Saves money by concentrating the security on a small number of components
  • Helps simplify the architecture of a system by restricting access only to machines that trust each other


  • A firewall cannot protect against any attacks that bypass the firewall. For example, other back-doors into the network.  
  • Firewall doesn’t protect against the internal threats from traitors. 
  • Firewalls can't protect against tunneling over most application protocols. For example, firewall cannot protect against the transfer of virus-infected programs or files. 

Features to Look For: 

  • Cost 
  • Graphical User Interface 
  • Efficiency in prohibiting potentially vulnerable services from entering or leaving the network 
  • Whether provides protection from IP and device spoofing 
  • Whether can be used to implement VPNs, audits and alarms 
  • Customizable, regular and automatic updates 
  • Technical support quality 
  • Ability to record and reports on events 

Best Options: 

Name: GlassWire firewall 
Free Trial: Completely Free

  • Wi-Fi evil twin detection: Provides alert notifications when the app finds new Wi-Fi hardware nearby with the same network name
  • Graph: Enables see a real time view of apps using the network and the type of traffic they're using, as far back as one month. This allows see when a specific program first connected to the network
  • Discreet alerts: Warns the users about network related changes
  • Monitors other PC’s on the network, and informs when any unknown device connects to the Wi-Fi
  • Tracks data usage
  • Lock Down Mode


  • Can't block all apps at once
  • Missing advanced customizations like port blocking rules


Name: ZoneAlarm firewall 
Free Trial: Completely free 

  • A firewall with anti-virus program 
  • Hides open port and provides real-time security updates as new threats are detected 
  • Multiple layers of securities - Public Network Protection, Wireless Network Protection and Real-Time Security Updates
  • Multi-platform: Windows 10, 8, 7, Vista, and XP
  • Light as feather 
  • Full stealth mode 
  • Offers 5GB of online data backup via IDrive
  • Customizable interface


  • Highest security setting flags everything, including safe programs
  • No exploit attack protection


Name: TinyWall firewall 
Free Trial: Completely free

  • Powerful scanning option for both inbound & outbound connections
  • Allows right-click any of these connections to abruptly terminate the process or even send it to VirusTotal, among other options, for an online virus scan.
  • Customizable options to alter protection from attacks
  • Real-time alerts, if anything wrong comes up
  • Instant firewall configuration, therefore great for beginners
  • Displays no pop-up ads
  • Allows white-list applications to prevent important programs from being blocked
  • Connections monitor shows all the active processes as well as open ports 
  • Lightweight 


  • No protection against exploit attacks


Name: Comodo firewall
Free Trial: Completely free

  • Virtual kiosk to easily block any program from entering or leaving the network
  • Offers a rating scan option, that lets you identify how much a program or process is trustworthy
  • Timely alerts about any suspicious files/ folders and programs
  • Comodo Kill Switch 
  • Offers an ad blocker
  • Sandboxing for less secure programs 
  • Multi-platform - Compatible with Windows 10, 8 and 7
  • Constantly updated threat database 
  • Browser clean-up utility 


  • No protection from exploit attacks 
  • Automatic sandboxing is disabled by default