A Guide To Firewall in a Computer Network

What is a firewall? It is a software or hardware based network security device that monitors all of the incoming as well as outgoing traffic. According to a specified set of security regulations, it will accept, deny, or drop that certain traffic. A firewall creates a barrier between an external untrusted network, like the internet, and secured internal networks.

The History and Importance Of Firewalls

The Access Control Listsor ACLs found on networks carried out the network security way back when firewalls didn’t exist yet. ACLs were regulations that decided if network access is to be provided or rejected to certain IP address.

However, ACLs are unable to determine the packet’s nature, which it intends to block. Additionally, ACL on its own doesn’t possess the capacity to keep the threats to the network at bay. And that’s why firewall was developed.

For organizations and companies, internet connectivity isn’t optional. But, accessing the internet offers advantages to the companies, it also lets the outside world to interact with the organization’s internal network. This develops a threat to the company. To make sure that the internal network is secured from unauthorized traffic, a firewall needs to be installed.

How Does Firewall Work?

Firewall works by matching the network traffic against the defined set of rules. When the rule has been matched, associate action will then be executed to the network traffic. The firewall rules could be defined according to the security policies and necessities of the company. For the server’s perspective, a network traffic could be incoming or outgoing.

Firewall would keep a set of rules for both instances. Most outgoing traffic, which comes from the server, are permitted to pass. Still, creating a rule on outgoing traffic is required for more security and to prevent undesired communication.

But it is different when it comes to incoming traffic. The majority of traffic that reaches the firewall is one of the three major Transport Layer protocols, which are the ICMP, UDP, or TCP. They all have a source address as well as a destination address.

Additionally, UDP and TCP all have port numbers. The ICMP does not use port number but a type code.

Generation of Firewalls

First generation – packet filtering firewall – used to regulate network access through the monitoring of incoming and outgoing packet and letting them go through or stop according to the source as well as the ports, destination IP address, or protocols.

Second generation – stateful inspection firewall – can determine the packet’s connection state, unlike the first generation, which means it is more efficient. It can track the state of the network connection that is traveling through it, like the TCP streams. The filtering decision will be based on the defined rules and the history of the packet in the state table.

Third generation – application layer firewall – it can filter and inspect the packets on any given OSI layer and even up to the application layer. It could block certain content, and determine if certain protocols and applications are being misused.

Next generation firewalls – they are deployed to prevent security breaches such as application layer and advance malware attacks. They consist of SSL/SSH inspection, Application inspection, Deep Packet inspection, and other essential features that help protect your network from modern threats.

Types Of Firewall

Host-based firewall – installed on every network node that controls every outgoing and incoming packet. It could be a software application or perhaps a suite of applications, which comes as a significant part of the operating system. They are needed since network firewalls can’t offer protection within a trusted network.

Network based firewalls – they operate on a network level. This means they filter all outgoing and incoming traffic across the network. It helps protect the internal network by using the defined rules on the firewall to filter the traffic. This type of firewall may have at least two network interface or NICs. A network based firewall is commonly a dedicated system that comes with an installed proprietary software.

Learn more about firewalls and how to set one up in your network by calling SpartanTec, Inc. in Columbia now.

SpartanTec, Inc.
Columbia, SC 29201
(803) 408-7166

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