What Is a Network Firewall and How Does It Function?

A firewall is one of the first lines of defense you may put in place to protect your network. Next-Generation firewalls have evolved to reduce the capacity of hostile attackers to steal critical information from a wide range of devices, in addition to preventing access to select networks.

As the Internet of Things (IoT) revolution brings new smart gadgets online, the need for firewalls cannot be overstated. Here, we’ll explain how firewalls work and how they may be used to secure your network and increase security.

What exactly is a firewall?

When an internet connection is used to get access to a private network, the mechanism is known as a firewall. Hardware and software firewalls, as well as hybrids, are all viable options.

So, what do they do for a living, you ask? Protecting your computer from malware-infested sites or open network ports is one of the primary functions of a firewall. Before they can do any damage, they assist put a halt to potential attacks. Intranets, which are private networks within a company, are examples of networks with network firewalls.

However, the network firewall security can be set up to restrict network users from accessing websites outside of their network. For example, parents can establish parental controls on their children’s browsing habits, or your company may block certain websites in order to keep you focused on the task at hand. 

What kinds of firewalls are there?

Packet filtering

This is the oldest type of firewall, but it doesn’t slow down your computer. A packet-filtering firewall can be compared to a traffic router or switch that employs a checkpoint.

Your router’s packet filter will examine all of the data packets that come through. The source IP address, the packet type, the source port, the destination IP address, and the destination port can all be evaluated by this filter.

It does not examine the contents of the packet, but rather provides generic information about its surface. In your network firewall security settings, you have the option to allow or deny packets from certain IP addresses or ports.

Because it’s so simple, an experienced hacker can easily get around it. This form of firewall should be used in conjunction with a more robust firewall system.

Gateway at the circuit level

In the same way that a packet filter approves or denies traffic, a circuit-level gateway does the same. They do their job by examining the protocol for transmission control (TCP). If the packet is from a real session, this test will show it to be genuine or not.

What is the actual appearance of this? It is impossible to establish direct connections between a trusted network and an untrusted network if there is a circuit-level firewall in place on the network.

This form of firewall can still be bypassed by hackers if they take advantage of an existing connection and send malicious packets.

Acting as a proxy server

This sort of firewall is regarded as the most secure because it does not allow direct network communication. The proxy firewall has the ability to inspect the full packet rather than just the IP address and port number. This firewall can better verify that the packet does not contain any harmful content by inspecting the packet information.

What precisely does this mean? Proxy firewalls can be used by managers of security issues, such as assessing the risks and vulnerabilities of the network.

What is the purpose of this firewall? In order to safeguard your internal network, you can set up a proxy server to limit access to various websites and filter certain port traffic.

An additional connection is made for every packet sent and received by a proxy firewall, which slows down system performance and can be the point of failure in an outside attack.

A firewall for your web application

A proxy server is a type of application gateway. The application gateway establishes a connection with the client machine A. Finally, the application gateway chooses whether or not the devices can communicate. A link is established to an external computer B if the user approves.

Application gateways connect client computers A and B to one other, as well as the application gateways to the outside world.

All traffic is screened by the application gateway before it is sent on. The application gateway IP address is the only one that can be viewed by the outside world, therefore the internal network remains hidden from the public eye.

What Firewalls Do?

An essential aspect of any security design, a firewall takes the guesswork out of your network’s host-level defenses and entrusts them to your network security device Malware and application-layer threats, as well as an integrated intrusion prevention system (IPS), is the emphasis of Next-Generation Firewalls, which can detect and respond to outside attacks throughout the entire network in a timely manner. Invasive or suspect activity, such as malware, can be quickly detected and shut off by a network security expert.

What’s the Purpose of a Firewall?

Malware and application-layer threats are the primary targets of firewalls, particularly Next-Generation Firewalls. The Sangfor Next-Generation Firewalls can detect and repel assaults throughout the network fast and seamlessly with an integrated intrusion prevention system (IPS). Invasive or suspect behavior, such as malware, can be quickly detected and shut down by firewalls that operate on previously established policies. Your network’s security infrastructure can be enhanced by implementing firewall policies that control which traffic is allowed to enter and which is blocked from leaving the network.

Application Layer vs. Network Layer

If packets don’t meet the specified rule set, they won’t be allowed to travel through the firewall. This is done at the network layer or packet filters, which check packets at the TCP/IP protocol stack’s lower level. Network layer inspection firewalls outperform their application layer inspection counterparts. However, this has the drawback of allowing potentially harmful software or malware to pass across permitted ports, such as outbound Internet traffic over HTTP and HTTPS protocols, ports 80 and 443.

Importance of VPN and NAT

Basic network services such as Virtual Private Network and Network Address Translation (NAT) are also performed by firewalls.  The IP addresses and Internal clients that may be in the “private address range” as stated in RFC 1918 are hidden or translated to a public IP address by use of Network Address Translation. The restricted number of IPv4 addresses is preserved by hiding the addresses of protected devices, and network spying is prevented since the IP address is obscured from the Internet.

Like a physical VPN, a virtual private network (VPN) encrypts packets as they travel over a public network, protecting the information they carry from prying eyes. By using this, users can send and receive data via shared or public networks without fear of being hacked.