What is a Firewall?

A firewall is a network security solution that monitors incoming and outgoing network traffic to permit or block data packets based on defined security rules.

Packets refer to data pieces formatted for internet transfer. They contain details such as the source and destination’s IP addresses and the message content. A firewall uses this packet information to allow or block network traffic based on a ruleset.

Just like the name suggests, a firewall solution acts as a barrier between a company network and external Internet and other sources. The security systems analyze and block malicious network traffic, such as malware and hacker requests.

Key Takeaways

  • A firewall is a software or hardware device that establishes a barrier between an internal network and an external Internet
  • Firewall products monitors and permits or block network traffic based on defined rules
  • There are different types of firewalls, such as stateless and stateful packet filtering firewalls, NGFW, proxy firewalls, and NAT firewalls.
  • Apart from monitoring traffic, a firewall can block malicious software from infecting your devices

You should update firewall rules regularly to keep up with the dynamic cybersecurity threats

A firewall uses pre-established rules and procedures to guard traffic at a network’s entry points or ports.

Types of Firewalls

A firewall can either be software, hardware, or both. A software firewall is installed on a network or computer devices to regulate traffic through applications and port numbers. A physical firewall is a device installed between a corporate network and gateway. A gateway is a computer network node (in most cases a router) that allows an internal network to the outside network.

Some examples of firewalls include:

  • Packet-Filtering Firewalls – this security system examines and permits or blocks network traffic based on a set of defined rules. For instance, the firewall has rules that check the data packet’s source and destination IP addresses to determine if the information matches rules allowed in the firewall. There are stateful and stateless packet-filtering firewalls.
    • Stateful Packet-Filtering Firewalls – a stateful firewall references information about previously approved packets.
    • Stateless Packet-Filtering Firewalls – a stateless firewall analyzes network traffic independently of any other. In other words, this firewall does not have a context.
  • Next-Generation Firewalls (NGFW) – an NGFW provides standard firewall capabilities and advanced features such as inspection of encrypted traffic. Besides, this firewall features antivirus and intrusion detection and prevention system capabilities. While a packet-filtering firewall analyzes only the packet header, an NGFW conducts deep packet inspection that involves examining details contained in both the header and the packet itself. Overall, an NGFW enables users to detect and block malicious traffic effectively.
    • Threat Focused NGFW – this firewall offers the functionalities of a standard NGFW and advanced threat detection and remediation. With a threat-focused NGFW, you can discover high-risk assets with complete context-awareness. The security system also provides intelligent security automation that sets policies and hardens other defenses dynamically
  • Proxy Firewalls – this security system filters network traffic at the application level. A proxy firewall sits between two end systems to monitor and approve or block HTTP and FTP protocol traffic. This product provides both stateful and deep packet inspection to mitigate cyber threats.
  • Web Application Firewall (WAF) – a WAF is a hardware, software, or a server plug-in filter that provides a set of rules to HTTP activities. You can customize the rules to meet your web application’s security needs.
  • Network Address Translation (NAT) Firewall – NAT allows multiple devices wit unique network addresses to connect to the Internet using a single IP address. This firewall, therefore, hides individual IP address, making it difficult for hackers to capture specific information while scanning a network.
  • Unified Threat Management (UTM) Firewall – a UTM security system combines the capabilities of a stateful inspection firewall, intrusion prevention, and antivirus. UTM firewalls can also offer cloud management services
  • Virtual Firewall – some vendors offer firewall products as virtual appliances in private and public clouds to monitor and secure traffic across virtual and physical networks. A virtual firewall is an essential security control in software-defined networks (SDN).

Why You Should Use a Firewall

A firewall prevents unauthorized Internet users and hackers from accessing your network and computers. The security system allows you to connect to the Internet and visit sites or share information without worrying about cybercriminals and threats.

Apart from scanning and blocking unwanted traffic, a firewall can prevent malicious software from infecting your systems.

In addition to immediate threat defense, firewalls perform crucial logging and audit functions. The appliances keep a record of events, which administrators and security experts can analyze to identify patterns and improve rule sets.

Where Can You Get a Firewall?

Popular operating system providers, such as Windows and macOS, build firewalls into their operating systems.

Third-party firewall products also exist. You can get reliable security solutions from vendors selling firewalls like Cisco ASA Firewall, Fortinet Fortigate, pfSense, Check Point NGFW, Cisco Firepower NGFW, Kerio Control, Sophos XG, and Palo Alto Networks NG Firewalls.

In some instances, home and small office broadband routers feature in-built fundamental firewall functionalities. For example, some routers offer port and protocol filters.

Keep the Firewall Updated

Keep updating the set rules regularly to keep up with the evolving and sophisticated cybersecurity threats. Firewall vendors discover new threats and develop patches to cover them. Ensure that you install updates as soon as they are released.