How does a firewall work?

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This post goes deep into how a firewall works.

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Malware usage increased by 358% through 2020. And ransomware usage increased by 435%, compared to the previous year. These statistics are based on a study byDeep Instinct.

Malware is any software purposely made to cause disruption to a computer, server, client, or computer network. Reveal private information. Obtain unauthorized access to information or systems. Deny users’ access to information. Or that mistakenly intrudes on the user’s computer security and privacy.

Then, ransomware is a type of malicious software intended to block access to a computer system until a sum of money is paid. Firewalls prevent malware and ransomware and any other attack designed to do harm to a system.

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Contents

What is a firewall?

firewall is a network security system that tracks and controls the incoming and outgoing network traffic based on predetermined security rules.

It sets up a barrier between a trusted network and an untrusted network. For example, the Internet.

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Types of Firewalls

Firewalls have types. As you know, there could be more than one way to achieve a goal. These are some types of firewalls:

a) Proxy firewalls

Proxy firewalls are put into effect at the application layer via a proxy device. Rather than an outsider accessing your internal network directly, the connection is established through the proxy firewall.

With this firewall type, the external client sends a request to the proxy firewall. After checking the authenticity of the request, the proxy firewall then forwards it to one of the internal devices or servers on the client’s behalf.

On the other hand, an internal device could request access to a webpage. And the proxy device will forward the request while hiding the identity and location of the internal devices and network

b) Circuit Level Gateways

Operating at the session layer, circuit-level gateways check established Transmission Control Protocol (TCP) connections. And also keep track of the active sessions.

They are rather similar to packet filtering firewalls in that they perform a single check and utilize minimal resources. Although, they function at a higher layer of the Open Systems Interconnection (OSI) model.

Principally, they ascertain the security of an established connection. When an internal device initiates a connection with a remote host, circuit-level gateways establish a virtual connection on behalf of the internal device to keep the identity and IP address of the internal user hidden.

c) Stateful inspection firewalls

Stateful inspection firewalls, check and keep track of established connections. They also perform packet inspection to provide better, more comprehensive security.

They work by generating a state table with source IP. Destination IP. Source port. And destination port once a connection is established.

These firewalls create their own rules dynamically to permit expected incoming network traffic. Rather than relying on a hardcoded set of rules based on this information. They suitably drop data packets that do not belong to a verified active connection.

d) Packet filtering firewalls

Packet filtering firewalls run at the network layer. They verify a data packet for its source IP and destination IP, the protocol, source port, and destination port against predefined rules to decide in the event to pass or discard the packet.

They are primarily stateless. Monitoring each packet individually without any track of the established connection. Or the packets that have passed through that connection previously.

How does a firewall protect data?

A firewall protects data by controlling the flow of data and traffic to or from your network. This kind of data is termed “packets.” That might or might not contain malicious codes to damage your system.

There are times when hackers aggressively attack your network with malware, spam, virus, and other malicious intent.

When this happens, your firewall applies a specific set of rules to the incoming and outgoing network traffic to inspect if they align with those rules or not.

  • -As long as it matches – the firewall allows the traffic to pass through.
  • -Otherwise – does not allow the traffic to pass through.

By doing this, your network remains safe from any kinds of threats. Either internal or external.