Network Security 101: A Deep Dive Into Implementing A Strong And Effective Firewall

Acting as your organization’s outer line of defense, a firewall monitors and filters all network traffic including outgoing traffic, application-layer traffic, online transactions, communications, and connectivity. It blocks incoming threats based on a set of pre-programmed rules that also may also control which users can access specific network areas.

Malicious actors and cyberattacks can cost organizations millions of dollars and result in serious network damage. This, in turn, can lead to poor productivity within your organization. To avoid this outcome and ensure you’ve set up your firewall effectively, we’ve put together an article that covers the key uses of a firewall, common mistakes, and some tips for best practice.

What Are Firewalls Used For? 

A firewall is a security system that is designed to prevent unauthorized access into or out of a computer network. Firewalls are used to monitor and control incoming and outgoing network traffic based on predetermined security rules. They sit between your organization’s local network and the wider internet to enforce what should or should not be allowed through. This approach can prevent threats from entering your organization’s network and prevent unauthorized access.

The primary purpose of a firewall is to prevent unauthorized access, data breaches, and malicious activity. Firewalls are a foundational security component that work to protect systems and data from external threats.There are various sub-categories of firewalls, such as Next-Generation Firewalls (NGFW) which include additional security capabilities like Intrusion Protection Systems (IPS) and threat intelligence.

Common Firewall Mistakes 

With the sheer amounts of data that firewalls have to sift through, there will inevitably be times when it fail to function as effectively as it should, putting your customers’ data and your company’s IT infrastructure at risk. Common mistakes that may cause firewall failures  include:

1. Assuming that firewalls are a “set it and forget it” solution 
   • Firewalls do not come ready to properly protect your network out of the box. They will require some initial configuration to ensure they are set correctly. 
   • Firewall rules should be reviewed periodically and updated as needed. 
2. Not keeping track of logs 
   • With no access to logs, organizations effectively have no idea if unusual activity or active attacks are taking place on their network.
   • Logs are also an invaluable forensic tool if a breach does take place.
3. Being too permissive with firewall policies 
   • Starting with a blanket “allow” policy on the firewall and slowly making it stricter over time can leave networks open to attacks for too long. Leaving a firewall completely or mostly open defeats the purpose of implementing one in the first place. 
   • Instead, it’s better to take the opposite approach – start with restrictive policies, then relax them until the minimum level of privileged required for essential functions is reached.
4. Overutilizing port forwarding 
   • When network traffic is directed to a device such as a network or firewall, that traffic will be headed towards a specific port number and IP address. Ports can be either open or closed. Some port numbers are reserved for specific services; i.e. port 25 for SMTP. 
   • Port forwarding can make services on your internal network reachable from an external network by redirecting where this data is routed. 
   • There are legitimate applications for port forwarding but using it irresponsibly can create opportunities for someone to gain unauthorized remote access to your network.

Firewall Implementation Tips 

Effective firewall implementation is critical to securing your network. Here are some key tips to ensure your firewall is configured and maintained properly:

1. Plan the firewall deployment process. We recommend a phased rollout to ensure that all components are running correctly and to minimize any potential disruptions. It is also important to fine-tune firewall policies according to your organization’s specific needs.
2. Follow standardized and consistent authentication practices. If different authentication standards are being used across the organization, the weaker one is the most likely to introduce vulnerabilities. This is especially important if employees need to have any form of remote access to company networks.
3. Only allow secure protocols to run on the network. Avoid using outdated and known insecure protocols such as Simple Network Management Protocol (SNTP) or Telnet. It is vital to keep compliance requirements in mind when implementing a firewall, to maintain auditable logs, and enforce access controls, making sure that only trusted personnel can make changes to the firewall. 
4. Stay aware of any known vulnerabilities, then take steps to mitigate risks where possible. To do this, ensure that firewalls stay up to date with any security patches from the firewall vendor and periodically check for any open ports or allow rules that are no longer needed.

For more information on firewalls from Expert Insights, we’d recommend reading the following articles: 

• The Top Network Firewall Solutions 
• The Top Firewall-as-a-Service (FWaaS) Solutions 
• Network Firewalls Buyers’ Guide 
• What Are The 5 Types Of Network Firewalls?