A Practical Business Firewall Review Checklist
A firewall can appear to be doing its job simply because the internet is still working. That is not a useful measure of security. A meaningful business firewall review looks beyond whether the appliance is switched on and asks whether its rules, subscriptions, monitoring and capacity still match the way your organisation operates.
For many businesses, the firewall was installed when the office had fewer users, fewer cloud applications and a much simpler network. Since then, remote working, Microsoft 365, SaaS platforms, guest Wi-Fi, new sites and third-party access may have changed the risk profile completely. Reviewing the firewall gives decision-makers a clear view of where exposure has developed and what should be addressed before an incident tests it.
What a business firewall review should achieve
A firewall review is not just a technical health check or a list of configuration settings. It should show whether your perimeter and network controls support the outcomes that matter to the business: protected data, reliable connectivity, operational continuity and the ability to grow without creating avoidable risk.
The review should confirm that traffic is only permitted where there is a clear business reason, that security features are active and properly maintained, and that someone is accountable for responding when the firewall identifies suspicious activity. It should also consider performance. Security controls that slow critical applications or cause intermittent connection issues tend to be bypassed, weakened or ignored over time.
For a multi-site organisation, the review should include how branches, cloud services and remote users connect. For a smaller business, the focus may be on removing historic rules, securing remote access and making certain there is a dependable support process. The principles are the same, but the priorities should reflect the environment rather than follow a generic checklist.
Start with the network you have now
The first question is simple: does the firewall configuration reflect reality? Many environments retain rules for old phone systems, retired servers, former suppliers or temporary projects that became permanent by accident. Every unnecessary rule is another route that needs defending.
A review should document the current network layout, including office locations, internet connections, wireless networks, servers, cloud workloads, line-of-business systems and remote access methods. It should also identify who administers the firewall and where the latest configuration backups are held. If nobody can confidently answer those questions, that is a governance issue as much as a technical one.
Pay particular attention to changes that may not have involved IT at the time. A new payroll platform, CCTV installation, warehouse system or managed print contract can all create network requirements. Understanding the business purpose behind each connection makes it far easier to decide whether it should remain open.
Review rules with a least-privilege mindset
Firewall rules should permit the minimum traffic needed for a specific service to work. Broad rules such as “allow any” between networks, open inbound ports with no recorded owner, or unrestricted outbound traffic from sensitive systems deserve immediate attention.
That does not mean every rule needs to be removed. Some applications require unusual ports or connections to external providers. The point is that each exception should have a named owner, a recorded purpose and a review date. Where practical, access should be restricted by source, destination, service and time rather than opened widely for convenience.
Rules should also be ordered sensibly and free of duplicates or conflicting entries. An overgrown policy can be difficult to manage safely, especially when changes are made under pressure during an outage. Clear naming conventions and change records make ongoing support much more reliable.
Check the security services, not only the rules
Modern business firewalls often provide much more than basic network filtering. Depending on the model and licences in place, they may inspect traffic for malware, block known malicious destinations, apply web controls, prevent intrusion attempts and identify applications travelling across the network.
These capabilities only help when they are enabled, licensed, updated and tuned for the organisation. A common finding is that a firewall has useful security functions available but inactive because a subscription expired, an initial deployment was never completed or alert volumes became difficult to manage.
A good review examines the following areas together:
firmware level and the vendor's current security support status;
active security subscriptions, signature updates and certificate validity;
intrusion prevention, malware scanning, web filtering and application controls;
encrypted traffic inspection, where appropriate and proportionate to privacy and performance requirements;
threat alerts, logging retention and the process for investigating them.
Encrypted traffic deserves careful consideration. Much web and cloud traffic is encrypted, which can limit what a firewall can inspect. Decryption can provide stronger visibility, but it requires the right certificates, tested exclusions and clear internal policies. It may affect certain applications or create privacy considerations. The correct approach depends on the data handled, the systems in use and the organisation's risk appetite.
Do not overlook remote access and cloud services
The traditional network boundary is no longer limited to the office. Users may work from home, suppliers may require controlled access, and data may sit across several cloud platforms. A firewall review should therefore consider identity as well as network traffic.
Remote access should use multi-factor authentication, named accounts and appropriate permissions. Shared VPN credentials and permanent access for former contractors are clear warning signs. Where possible, access should be limited to the systems a user genuinely needs rather than granting a broad route into the network.
Cloud services create a different set of questions. Are there secure connections between sites and cloud workloads? Is traffic being routed in a way that preserves visibility and performance? Are cloud security controls being relied upon instead of, or alongside, firewall controls? There is no single answer, but the responsibility for each layer must be clear.
For organisations with several offices, resilience is equally important. A second internet connection, failover configuration and tested site-to-site connectivity can prevent a single connectivity failure from becoming a business-wide disruption. However, redundant connections are only valuable if failover has been tested and security policies apply consistently when traffic switches routes.
Measure capacity against business growth
A firewall can become a bottleneck long before it fails outright. Vendor performance figures are often based on ideal conditions and may not reflect real-world use of VPNs, encrypted traffic inspection and threat prevention services at the same time.
Review current bandwidth use, the number of connected devices, peak remote-user demand and the applications that are most sensitive to delay. Then compare this with the firewall's expected performance when all required security features are enabled. This is particularly relevant before opening another location, moving a core system to the cloud or introducing bandwidth-heavy tools such as voice, video or AI services.
Capacity planning is not about buying the largest appliance available. It is about selecting a service level that supports the next stage of growth without paying for capability that will never be used. A trusted IT partner should be able to explain that trade-off in plain English, backed by evidence from your environment.
Turn findings into an owned improvement plan
The value of a firewall review comes from what happens afterwards. Findings should be ranked by risk and business impact, separating urgent issues from sensible improvements that can be scheduled around operational priorities.
An effective action plan identifies the change required, the system owner, the expected benefit, the likely impact on users and how success will be tested. It should also include routine tasks: reviewing rules, checking licences, applying firmware updates, testing configuration restores and examining alerts. Security is not a one-off project, particularly where systems and working practices continue to change.
For businesses without an in-house security team, managed monitoring and support can provide the accountability that is often missing after deployment. The aim is not to create more alerts for someone to ignore. It is to ensure that meaningful issues are assessed, acted on and communicated clearly to the people responsible for the business.
A firewall should be a safe pair of hands in the background, not an unknown box in a comms cupboard. Reviewing it regularly gives your organisation the confidence to make changes, support users and pursue growth without leaving yesterday's assumptions exposed.
