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What is a Perimeter Firewall?

In today's business world, our reliance on a linked ecosystem of internet gadgets has increased our reliance on network security to combat cyber attacks. On a huge scale, data is collected, aggregated, and interpreted, and its security is based on the safeguards that surround it. The notion and evolution of a network perimeter enable enterprises to successfully think about how to protect their internal information from untrustworthy or hostile actors.

Over the decades, a perimeter firewall has proven its worth as a means for screening out malicious traffic before it passes from a public network into a private network.

A perimeter firewall, also known as an external firewall, is a security solution that protects the border between a company's private network and public networks like the internet. A perimeter firewall can be implemented as either software, hardware, or both to serve as the first line of defense in enterprise security. A perimeter firewall inspects packets entering and exiting a private network and either allows or blocks them based on pre-defined criteria.

How Does a Perimeter Firewall Work?

A perimeter firewall protects a network from intruders by inspecting all traffic before allowing it to enter. For example, if a business does not want its employees to be able to access social media sites such as Instagram or Facebook, the perimeter firewall can be configured to prevent them from doing so.

How Does a Perimeter Firewall Work

Figure 1. How Does a Perimeter Firewall Work?

Perimeter firewalls, as the first line of protection against cyber-attacks, use a variety of ways to regulate traffic between an organization's network and untrusted networks. Let's go over a few of them.

Static packet filtering: Static packet filtering is a technique in which the firewall filters traffic based on packet fields and rules defined by the network administrator. Each packet received by a static packet filtering firewall is examined and compared to ACLs. It then permits or rejects traffic into the organization's network based on the rule.

Static packet filtering is one of the oldest firewall approaches, operating at Layers 3 and 4 of the Open Systems Interconnection (OSI) paradigm. As a result, it is unable to distinguish between application layer protocols. It also does not protect against spoofing attacks.

Proxy-based firewalls: Proxy firewalls act as a bridge between internal networks and external networks such as the internet. The proxy functions as an initial intermediary connection between the requester and the resource, preventing direct packet transfers from either side of the firewall and making it more difficult for intruders to determine the network's location based on packet information.

Stateful packet inspection: Stateful inspection, also known as dynamic packet filtering, keeps track of incoming and exiting traffic. It then only permits traffic to pass if it matches a previous request. Stateful packet inspectors prevent spoofing and improve network performance and network scanning from external networks.

Next-generation firewall (NGFW): To provide enterprise-wide security, a typical NGFW employs both static packet filtering and stateful inspection, as well as other features such as deep packet inspection (DPI). To improve security, it may also include advanced security features such as network security systems (IDS) and IPS), antivirus filtering, and malware filtering.

Is Perimeter Firewall DMZ?

A DMZ, or demilitarized zone, in computer networks is a physical or logical subnet that separates a local area network (LAN) from other untrusted networks, most commonly the public internet. Perimeter networks and screened subnetworks are other names for DMZs.The DMZ network, also known as the Perimeter Network, is a distinct network used for hosting web servers, e-mail servers, FTP servers, and other public servers that need to connect to or from the internet.

What is Perimeter Network Used For?

A network perimeter is the security barrier that separates the private and locally managed side of a network, which is typically a company's intranet, from the public-facing side of a network, which is typically the Internet.

Perimeter networks allow you to connect your cloud networks to your on-premises or physical data center networks in a secure environment. They also provide secure access to and from the internet. A perimeter network is sometimes known as a demilitarized zone or DMZ.

A perimeter network is a distinct network used for hosting web servers, e-mail servers, FTP servers, and other public servers that need to connect to or from the internet.

What Are The Benefits Of a Perimeter Firewall?

Perimeter firewalls are an important part of any network security strategy. The present cyber landscape is witnessing increasingly complex attacks as well as advancements in solutions such as the next-generation firewall (NGFW), which provide stronger security against emerging but unknown dangers.

  • Monitor Network Traffic: Perimeters Firewalls enable comprehensive surveillance of both incoming and outgoing packet transfers. They provide detection and security against harmful content submitted into the network. The continual analysis of a network to discover and solve any performance faults is known as network monitoring. Network monitoring entails gathering network statistics in order to assess the network's service quality. Monitoring network hardware and software devices such as routers, firewalls, switches, servers, and WiFi is part of continuous network monitoring and evaluation. Network monitoring can help you pinpoint the exact location of a network problem or demonstrate that the network is not the issue. Continuous monitoring can assist you in detecting possible problems before they materialize. It implies that you can correct problems before they affect users. For example, you can detect and resolve issues such as network slowdown before they disrupt business operations. Detecting such concerns early on help salvage your company's reputation. Customers will be able to access your company, which will lead to client happiness.
  • Prevent Hacking: Cybercriminals are continuing to launch more complex attacks and threats. External hackers were responsible for over 70% of breaches in 2020, according to the Center for Internet Security. With the dramatic increase in reported hackings, perimeter firewalls are more vital than ever in stopping external hackers from infiltrating an organization's network. A perimeter firewall is useful because it can manage the entrance points to your network and prevent malware attacks. Trojans are malicious programs that infiltrate networks by attaching themselves to computer files. They can provide hackers with knowledge about network weaknesses or launch even more dangerous assaults from within; firewalls can detect and prevent Trojan attacks. Malicious persons have developed hundreds of thousands of spyware to access networks since the world became data-driven. The first step in preventing spyware is to install a perimeter firewall. Keyloggers are pieces of malware that aim to record keystrokes and steal sensitive information like PIN numbers and account passwords. Perimeter firewalls also is a good solution for keylogger prevention.

What Are The Risks Of a Perimeter Firewall?

Some of the dangers to consider when planning around a perimeter firewall are as follows:

  • Cloud Risk: As more firms move their data and applications to non-owned infrastructures such as data warehousing, cloud computing, and SAAS, they must change their policies to meet current threats. Companies must recognize that traditional perimeter security measures are no longer effective now that their essential data and applications have migrated to the Cloud. The Cloud is changing not only where business data is housed, but also how it is accessed, and how exposed it is to new types of attacks. On a regular basis, data centers are subject to cyber-threats in the corporate world. Cyber-attacks may have a substantial negative impact on businesses, and a single data breach can cost a lot of money and take a long time to recover from. This is due to the fact that the Cloud now connects to a substantial amount of the company's data. Three reasons why perimeter security is insufficient for cloud computing are listed below:
    • Organizations no longer have a well-defined boundary.
    • The bad guys are already inside.
    • More security breaches are caused by simple mistakes than by malevolent attempts.
  • Unknown Device Risk: Employees and consumers are connecting to their organization's network from other networks and mobile devices, increasing the danger of penetration. Because of the increased mobility of the workforce, a compromised employee's device can allow hackers to enter the network without breaking the perimeter.
  • Risk of Web Services: Offering or using web services may necessitate opening up the company's network to outside networks. Consolidation and data integration are required since business processes are carried out across multiple systems. Interfaces are often used to connect mission-critical applications to other apps and organizations. An attacker could use these interfaces to migrate laterally and target other systems and apps in order to compromise the most critical systems. Furthermore, as cloud migrations and digital transformation programs develop, many mission-critical applications are being transferred to cloud environments. In other circumstances, these apps are accessible via the Internet, adding another layer of complexity and potential attack surface that might eventually be used to gain access to business-critical applications.

What is the Difference Between Perimeter Firewall and Other Firewalls?

In several aspects, perimeter firewalls differ from other types of firewalls such as Client Firewall (host-based firewall) and data center firewalls (also known as internal firewalls).

What is the Difference Between Perimeter Firewall and Client Firewall?

Network Perimeter Firewalls, as the name implies, are primarily used to defend whole computer networks from attacks as well as to restrict network traffic so that only allowed packets may reach your servers and IT assets.

The most common application for a network-based firewall is as an Internet border device to protect a company's LAN from the Internet.

A Client Firewalls(host-based firewall), as the name implies, is a software application that is placed on host computers or servers to protect them from threats. The client firewall is installed directly on the host as software and regulates incoming and outgoing traffic to and from the specific host.

The Windows Firewall, which is included by default in all Windows operating systems, is a classic example of a host firewall.

Because this sort of protection is attached to the host, it protects the host regardless of whatever network it is connected to.

If you are linked to your workplace network, for example, you are already protected by your network firewall. If you connect your laptop with a host-based firewall to an external WiFi network, the firewall will still protect the computer.

CharacteristicsPerimeter FirewallClient Firewall
PlacementInside the network (either at the border/perimeter or inside the LAN)On each host
Hardware/SoftwareHardware DeviceSoftware Application
PerformanceHigh performanceLower performance (since it is software-based)
Level of protectionNetwork security as well as application-level security (if using Next-Generation Firewall)Network protection plus Application protection
Use-casesMostly in Enterprise NetworksUsed in both home networks for personal PCs and enterprise networks for further host protection.
Network SegmentationAt the VLAN / Layer 3 level, there is excellent segmentation and management, but communication between hosts in the same VLAN cannot be restricted.Even if the hosts are on the same VLAN, there is excellent micro-segmentation at the host level.
MobilityOnce a firewall is implemented inside the network, it is very hard to remove or change.Because it is connected to each host, it has high mobility.
ManagementCan be administered from a centralized firewall management server or directly from the appliance.Hard to manage when hundreds of hosts exist in the network.
How easy to BypassNetwork firewalls can't be bypassed by attackers.Easier to bypass. If the attacker compromises the host via an exploit, the firewall can be turned off by the hacker.

What is the Difference Between Perimeter Firewall and Data Center Firewalls?

Datacenter Firewall is a stateful, multitenant, network layer, 5-tuple (protocol, source, and destination port numbers, source and destination IP addresses) Software Defined Networking (SDN) firewall. The Datacenter Firewall safeguards traffic flows east-west and north-south across the network layer of virtual networks and regular VLAN networks.

Datacenter firewalls are designed to protect virtual computers, as opposed to network perimeter firewalls. They are also intended for the agility that data centers require, allowing managers to reallocate virtual resources as they see appropriate without violating firewall restrictions.