5 secure ways to configure a firewall


Internet access is no longer an option; it has become a requirement for everyone. Internet connection has its own set of benefits for an organization, but it also allows the outside world to communicate with the organization’s internal network.

Visiting another website requires a connection to a specialized computer called a web server, which, like any other computer, can be targeted by hackers. Attackers have the potential to infect the host computer with malware and launch DDoS attacks when connecting to a foreign machine.

This is where a firewall comes in handy.

A firewall is a type of network security device that monitors and controls incoming and outgoing traffic. It can be hardware or software. It allows, denies or blocks specific traffic based on a predetermined set of rules. It protects the network from external and internal threats.

How does a firewall work?

When encountering unauthorized traffic, a firewall performs analysis and attempts to match the traffic against its defined set of rules. Once the network matches the set of rules, the appropriate actions are taken for that specified network. If incoming traffic is determined to pose a security risk, the firewall blocks it from entering the internal network.

The vulnerability of networks connected to the Internet requires the use of firewalls. A third party can easily infiltrate and infect an unprotected network. The hacked website or server may be infected with malware once the hackers take control of it. Distributed Denial of Service (DDoS) attackswhich can force a website or server to crash, can make your network vulnerable if no firewall is installed.

A firewall can filter and control unauthorized traffic in various ways, such as:

In this strategy, packets consist of small pieces of data that are processed separately by firewalls. Packets trying to enter the network are checked against a set of rules. Packets that match a known threat are quarantined, while others are allowed to proceed to their intended destination.

This form of firewall has no way of knowing if the packet is part of an existing traffic flow. Packets can only be allowed or denied based on their unique headers.

Stateful Inspection is a more advanced type of firewall filtering that examines a variety of items in each data packet and compares them to a database of trusted data. The source and destination of IP addresses, ports, and applications are among these factors.

In order to gain access to the internal network, incoming data packets must contain the required information.

To protect network resources, proxy firewall, also known as application firewall or gateway firewall, inspects incoming traffic at the application layer. It limits the type of applications a network can support, which improves security but reduces functionality and performance.

A proxy server acts as an intermediary, preventing direct connections between the two sides of the firewall. Each packet must pass through the proxy, which determines whether traffic is allowed through or blocked based on established rules.

  • Next Generation Firewall (NGFW)

Next Generation Firewalls (NGFW) are used to guard against modern security threats such as malware and application layer attacks. Packet inspection and stateful inspection are combined in NGFW. To protect the network against modern threats, it also contains deep packet inspection (DPI), application inspection, malware filtering and antivirus.

The importance of a correct firewall configuration

A firewall is an important part of network security and must be configured properly to protect a business from cyberattacks and data breaches. Hackers can gain unauthorized access to a protected internal network and steal critical information if the firewall is misconfigured.

A properly configured firewall can protect an online server from harmful cyberattacks to the greatest extent possible.

Safe ways to configure a firewall

Firewall settings are essential to ensure that only authorized administrators have access to a network.

The following actions are required:

  • Securing the firewall to authorized personnel

Secure your firewall so that only authorized personnel can access the internal network.

  • Update your firewall to the latest firmware.
  • A firewall should never be put into production without the proper configurations in place.
  • Delete, disable or rename default accounts and use unique and complex passwords.
  • Never use shared accounts managed by multiple administrators.
  • Disable Simple Network Management Protocol (SNMP).
  • Creating Firewall Zones and Establishing IP Addresses

Decide which assets need to be protected and map your network so that these assets can be grouped and assigned to different networks or zones based on their functions and sensitivity levels. The more zones you build, the more secure the network will be.

However, managing multiple zones requires more effort, so assigning zones to firewall interfaces and subinterfaces requires establishing associated IP addresses.

  • Configuring Access Control Lists (ACLs)

Access control lists are used by organizations to determine what traffic is allowed to pass or denied (ACL). ACLs are the rules that a firewall uses to determine what actions to take in response to unauthorized traffic attempting to gain access to the network.

The actual source and destination port numbers and IP addresses must be specified in the ACLs. Each ACL must have a “Deny All” rule to allow organizations to filter traffic. The interface and subinterface must be both inbound and outbound to ensure that only authorized traffic reaches a zone.

  • Configuring firewall services and logging

Other services, such as an intrusion prevention system (IPS), an NTP (Network Time Protocol) server, and others, may be integrated into some firewalls. It is essential to disable any additional services supported by the firewall that are not in use.

  • Testing the firewall configuration

It is crucial to test your firewall settings once you are sure they are correct. Tests such as Vulnerability Assessment and Penetration Testing (VAPT) is crucial to ensure that the correct traffic is allowed to pass and that the firewall works as expected. If the firewall configuration fails during the test phase, perform a backup.


Like a CERT-In incorporated cybersecurity solutions company, Kratikal provides a comprehensive suite of VAPT testing services, one of which is Network Security Testa method for evaluating the external and internal security status of a network to detect and illustrate vulnerabilities present within the network.

The Infrastructure Penetration Test includes a variety of tasks such as:

  1. Identify, prioritize and quantify threats within the network.
  2. Security check verification.
  3. Analyze defenses against network-based attacks such as brute force attacks, port scanning, among others.

Kratikal also offers firewall auditing. The evaluation methodology includes proper planning and execution.

The steps followed are:

  1. Security configuration review
  2. Review firewall ruleset or review ACL
  3. Firewall audit test scenario
  4. Reports

Depending on business and technical requirements, we use standard security testing tools such as Burpsuite, Nmap, Metasploit and others in each IT architecture.

The relevance of firewall configuration to the security of our networks cannot be overstated. Firewalls protect our IT infrastructure, but they too require regular maintenance to function properly. A functioning firewall also ensures that our networks remain healthy.

What other configuration options do you see for a firewall? Let us know what you think in the comments section below!

The post 5 Secure Ways to Configure a Firewall appeared first on Kratikal Blogs.

*** This is a syndicated blog from the Kratikal Blogs Security Bloggers Network written by Deepti Sachdeva. Read the original post at: https://www.kratikal.com/blog/5-secure-ways-to-configure-a-firewall/


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