What is Firewall And How Does It Work



A firewall is a network security program or device that monitors outgoing and incoming network traffic and decides whether to allow or block specific traffic threat based on a predefined set of security rules.

Firewalls have been a first layer of defense in network security for many years. They create a barrier between secured and controlled internal networks that can be trusted and non trusted outside networks, such as the Internet. 

A firewall can be software, hardware or both

  • Hardware

Hardware type firewall typically consists of a separate device or computer dedicated to running the firewall software functions easily and smoothly.

  • Software

Software type firewall provides a variety of applications, in terms of network security; a firewall provides these security controls through a variety of technologies:

    • Internet Protocol (IP) packet filtering
    • Network address translation (NAT) services
    • SOCKS server
    • Proxy servers for a variety of services such as HTTP, Telnet, FTP, and so forth
    • Mail relay services
    • Split Domain Name System (DNS)
    • Logging
    • Real-time monitoring


How a firewall works

To understand how a firewall works, imagine an example that your network is a building to which you want to control access. The one and only entry point to the building is lobby. In this lobby, you have receptionists to welcome visitors, video cameras to record visitor actions, security guards to watch visitors,  and badge readers to authenticate visitors who enter the building.

These measures work well to control only private access to your building. But, if an unauthorized person succeeds in entering your building, you have no way to protect the building against this intruder’s actions. If you monitor the intruder’s movements. However, you have a chance to detect any suspicious activity from the intruder, similar way a firewall works

What a firewall can do to protect your private network

You install a firewall between your network and your connection point to the  non trusted network or the internet. Then you can limit the point of entry to your network. A firewall provides a single point of contact known as a chokepoint between your network and the Internet. Because you have a single point of contact, you have more control and ease over which traffic to allow in and out of your network.

A firewall seems as a single address to the public. The firewall provides access to the non trusted network through proxy servers or network address translation (NAT) or SOCKS, while hiding your internal network addresses. Consistently, the firewall maintains the privacy of your internal network. Keeping information about your network private is one way in which the firewall makes an imitation attack (spoofing) less likely to happen.

A firewall allows you to control traffic into and out of your network to lower the risk of attack to your network. A firewall securely filters all traffic that enters your network. So that only specific types of traffic can enter specific destinations. Finally, this minimizes the risk that someone might use File Transfer Protocol (FTP) or Telnet to gain access to your internal systems


Types of firewall

    • ZoneAlarm
    • Tinywall
    • Anti NetCut3
    • Comodo Free Firewall
    • PeerBlock
    • Little Snitch 
  • Private Eye

Firewall implementation

In practice, firewalls are likely to be combinations of the types that have been described. For ex- a screened sub-network is commonly include in a firewall scheme, in this configuration an entry level gateway implemented in a host, is used in combination with two packet-filtering routers to filter. Overall, Place servers and dial-in modems that are accessed by external users in a DMZ (demilitarized zone). This is the best way of separating higher-risk components from fully protected internal network. Both external hosts and internal hosts (within the network host)have access to services provided on the DMZ. But traffic across it blocks preventing external users from gaining direct access to the protected internal network

In short, Firewalls play an important role in controlling and restricting access to a private network. A firewall is normally planted within a gateway or router, and will monitor all incoming and outgoing traffic at the boundary of the protected zone. It is a protocol that restricts external host’s access to selected insecure services or websites within the protected zone. While also denying internal hosts access to insecure services and sites outside the protected zone. There may be further control within the protected zone. For example, limiting access from one internal LAN server to another server. A firewall provides means to implement and encodes some of an organization’s network security policies. However, This may be transparent to users of the network in terms of its presence and the level of inconvenience caused. Therefore, this totally depends on the type of firewall and the codes that are implemented.

Deployment And Acceptance

The fast deployment and acceptance of the internet has revolutionized. Based on, how we share and build information, financial transactions, personal information, healthcare records and government data all pass instantly through technological systems at record place.  Here, Internet technologies have the way people communicate to each other, society functions, businesses operations and governments management,

But, revolution and innovation always comes as risk factor, security breach is always the last layer to be added in any transformation idea, and cyber attacks and malware now threaten the societal progress and economic that these technology tools provide us. They have created an environment of exposures and vulnerability, where individuals and corporations can’t feel safe. The experience of being online, of integrate across geographies, of exchanging information safely.

Comodo, a company that has been built upon the foundation of believing and trust that even single transaction must have a built-in layer of security. Thousands of organizations and companies rely on Comodo’s technology to validate secure and authenticate their most precious asset that is information – and to combat constantly with malware threats and cyber attacks that are creating havoc on a global scale nowadays.


Lastly, From the corporation to the individual, everyone has the right to a secure and trustworthy environment.

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