What is Network Firewall Security | Privacy Aspects & Advance Level?

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With the advancement in technology, the use of the internet has evolved in almost all sectors. 

From day-to-day communication for personal and organizational purposes to accessing servers miles away from your organization at some other company’s data centers, the ease that the internet’s evolution has brought upon us is satisfying.

But there are security issues, hacking problems, and unwanted interference. To deal with the internet’s cybersecurity flaws, we use firewalls to restrict the amount and type of traffic that comes through our services. Read the remaining article and get more insight into firewalls.

What is a Firewall?

A firewall can be software or hardware, depending upon your needs. That is needed to secure the connection between your computer and the internet. 

A firewall determines what data can pass between the user and the internet. It depends upon how the network administrator has configured the firewall. Sometimes firewall is an application software like PFSense. But most of the time, network administrators tend to use firewall hardware like Cisco Firepower Series.

 A good firewall like mentioned above is good enough to deal with internal and external threats. It also deals with malicious threats like worms or ransomware from acquiring access to the network if there is no loophole left behind in the firewall configuration. 

How Does a Firewall Work?

Sometimes while being at work, you might not be able to view certain content over the internet. It’s because your network administrator might have blocked the access through a firewall.

When you connect to a website, your computer generates an HTTPS request. Your web browser wraps it into a TCP packet (Transmission Control Protocol). The Header contains information such as source and destination addresses, source and destination ports, and packet sequence information, including the data (Payload). The website’s identification is its IP address, and the IP layer receives the TCP packet for routing. The IP layer determines where to send the request, which is usually the website’s server.

But when a firewall is securing the network, it controls the IP layer. It uses its tracking protocols to check all the packets at either side (Sending and Receiving) of the connection. It does so by completely isolating your device from the web.

By guarding the port through which data packets are being sent or received, the firewall makes sure whether the data should be allowed to pass or be blocked. 

Types of Firewalls

Whether it is an application or a hardware-based firewall, they both work in the same way. Firewalls are of the following types depending upon their features. 

So, Let’s take a look at different types of firewalls.

Packet-Filtering Firewalls

The most common type of firewall used is the packet-filtering firewall. It examines the source and destination IP address and lets it pass through or blocks depending upon if you have used an IP filter.

A TCP packet’s header information is checked and depending upon your rules, it will either go through or get blocked. 

A packet filter firewall is a fast solution and the most common one. But the drawback is that it only checks the header and not the payload. This makes the TCP packet get through to your computer with a malware load and infect your device. 

Stateless Firewalls

Stateless firewalls are the same as packet-filtering firewalls. They protect the networks based on static information such as source and destination IP addresses and ports.

They use packet filtering rules that specify certain conditions. As soon as the conditions match, stateless firewalls use specific pre-approved actions to guide the data packet into the network. If there is no match, then the data packet gets blocked.

Stateful Firewalls

A Stateful Firewall monitors the full state of active network connections. Rather than discrete traffic and data packets, they analyze the complete context of incoming traffic or data packets. 

Once the approval of a certain kind of traffic, it’s added to a state table and can move into the protected network. Those that don’t fulfill the required needs get blocked. By considering various factors like TCP stages, stateful firewalls can observe traffic streams in their entirety.

But, Stateful Firewalls can fall prey to DDoS attacks. It’s due to intense compute resources and their software-network relationship to verify connections.

Next-Generation Firewalls (NGFW)

The Next Generation Firewalls combines several functions of other firewalls into one. NGFW checks the actual payload of the packet inside instead of focusing only on the header. 

NGFW contains antivirus, intrusion prevention systems, encrypted traffic inspection, and Deep Packet Inspection.

Once the contents inside the TCP packet are approved, the packet passes on the network; otherwise, it gets blocked.

Proxy Firewalls

Proxy Firewall operates at an application level, transitioning between two end systems. They establish the connection and do an in-depth examination of data packets coming through the servers. 

The drawback is that they cause a network slowdown because of all the extra steps it has to do to keep you safe and secure. 

Circuit Level Gateways

They are much like Packet filtering firewalls. They are a bit quicker than Packet filtering firewalls and check and approve or deny traffic. They do it without being heavy on the resources. 

Circuit level gateways work by verifying the TCP handshake. But it doesn’t check the packet in-depth, so there is a risk of malware getting through.

Network Address Translation (NAT) Firewalls

Like the proxy Firewall, NAT Firewalls acts as an intermediary between two end computers.

With NAT Firewall, multiple devices with separate network addresses can access the web using a single IP address hiding their own IPs.

Cloud Firewalls

Firewall as a Service (Faas) or Cloud Firewall is a cloud solution for network protection. It goes hand in hand with Proxy Firewalls.

Their main advantage is scalability. They are independent of physical resources, which allows scaling the firewall according to the traffic load.

How To Bypass Firewalls?

There are quite a few ways to bypass the network restrictions imposed by firewalls. Some are cheaper, while others are more effective. 

Using UltraSurf

UltraSurf connects to the nearest proxy server on your desktop default browser. It opens a private window in that browser and allows you to access restricted websites through the proxy server.

As it doesn’t need any installation, you can use UltraSurf on restricted devices.

The only drawback of UltraSurf is that it is available only on Windows.

Using Tor Browser

Tor, “The Onion Router,” is one of the most famous browsers that allows users to browse the web anonymously.

Tor routes your web browsing over an encrypted network. It sends your request through 3 different nodes selected randomly before reaching the destination. It also allows you to use restricted websites by encrypting your data that most firewalls can not detect. Moreover, the data packets pass through it without getting blocked.

The only downside of this web browser is that it is slow, and sometimes you might lose your patience even if it is letting you access the restricted websites.

Using Proxy Server

A Proxy Server acts as a middleman for your device and the internet. But make sure that you use a paid proxy server. A free proxy server will waste your time by spamming hundreds of advertisements. 

A firewall doesn’t detect that you are visiting blocked websites. All firewalls will see that you are sending and receiving data packets from a trusted website.

Using Your Smartphone As A Hotspot

If your carrier allows tethering, you can connect your smartphone with your laptop via a lightning cable and turn on tethering. 

As soon as you turn tethering on, your network would change from your laptop. You can access restricted websites as the network’s firewall restrictions have been lifted cause you are not on that network anymore.

Using VPN

VPNs are one of the best solutions to bypass firewalls. But not all VPNs let you skip the firewall restrictions as most of the free VPNs do not correctly mask your IP address.

A VPN alters your routing tables. It means that the IP layer that delivers your data packets now routes your outgoing traffic into the VPN. The VPN application wraps the whole IP datagram into another TCP packet sent to the VPN Servers.

Now we know how your original data packet becomes invisible to the IP layer. Once the data reaches the VPN servers, it’s unwrapped and sent to the destination in its original form. This tunnel effect is what the VPNs are so famous for. By sending the TCP packets through the VPN, you bypass the firewall and the routing rules. 

Ensure that the VPN service you signed up for provides adequate features to keep your identity and data safe at all times. A no-log policy is essential so that you may know that no one is trying to look over your shoulder while browsing the web. 


Firewalls are essential aspects of our security. They keep us safe from different kinds of worms and malwares that are a threat to our privacy and cause a breach in our sensitive information stored on our devices. 

Using a VPN is one of the safest and the most secure ways of bypassing the firewall. A VPN provides you with the same security (sometimes even greater depending on which VPN you signed up for) and enhanced privacy over the web.

Kenneth G Aranda

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