Your corporate firewall is still one of the most important barriers between your business and the outside world. It helps control what enters and leaves your network, blocks unwanted traffic and reduces the chance of attackers reaching sensitive systems.
But a firewall is not something you simply install and forget about.
In the UK Government’s Cyber Security Breaches Survey 2025/2026, 43% of businesses reported a cyber security breach or attack in the previous 12 months. The figure was even higher for medium businesses at 65% and large businesses at 69%. That does not mean every business needs a complicated security setup, but it does show why the basics matter.
A well-configured firewall can help reduce risk, but only if it is managed properly. Poor passwords, unused rules, default settings and weak access policies can all leave gaps.
Here are some simple, practical tips to help secure your corporate firewall.
Start with firewall hardening
Firewall hardening means removing anything that does not need to be there. The idea is simple. The more services, accounts, open ports and default settings you leave active, the more opportunities you give an attacker.
Start by reviewing the firewall configuration carefully. Remove unused services. Disable unnecessary management access. Change default usernames and passwords. Make sure firmware and software updates are applied. Check whether old rules are still needed or whether they were only created for a temporary project.
This is where wider IT security services can be useful. Firewall hardening should not sit on its own. It should fit into your broader security, device and user access controls.
You should also make sure someone owns the process. If nobody is responsible for reviewing the firewall, it is very easy for old settings to remain in place for years.
Use strong passwords and proper admin access
Weak admin passwords are still a serious risk. Attackers often prefer the simplest route into a system. If your firewall has a weak password, a shared login or an old admin account that nobody checks, you are making their job easier.
Use long, unique passwords or passphrases for firewall administration. Avoid reusing passwords across different systems. Do not share one admin login between several people if you can avoid it. Each administrator should have their own account, with only the access they genuinely need.
Multi-factor authentication should also be used wherever your firewall or management platform supports it. This adds another layer of protection if a password is stolen or guessed.
Credential exposure is a growing issue for UK businesses, especially when staff reuse passwords across different services. Dark web monitoring can help identify whether business email addresses or credentials have already appeared in breach data or criminal spaces.
Customise the firewall around how your team works
Default firewall settings are rarely perfect for your business. They may block something your staff genuinely need, or allow more access than is sensible.
The answer is not to let users disable protections when they get frustrated. That creates more risk. The better approach is to configure the firewall around real business needs.
For example, if a trusted platform needs to be accessible for a finance team, create a specific rule for that requirement. If a department no longer uses a certain service, remove that access. If remote workers need secure access, use approved VPN or zero trust access rather than broad open rules.
This is where practical IT consulting can help. A good review should look at users, systems, cloud tools, devices and business workflows, not just the firewall in isolation.
If your business relies heavily on Microsoft 365, email, Teams and cloud systems, your firewall rules should also sit alongside secure identity and account controls through cloud services and Office 365 support.
Deny first, then allow what is needed
A sensible firewall policy usually starts from a deny-first position. That means traffic is blocked by default, and only approved traffic is allowed through.
This is much safer than allowing broad access and then trying to block risky traffic one rule at a time. The deny-first approach gives you more control and a clearer view of what your business actually needs.
You should document each rule clearly. Include what the rule does, why it exists, who requested it and when it should be reviewed. This may sound basic, but it can save a lot of confusion later.
Without documentation, firewall rules often become a collection of old exceptions. Nobody wants to remove them because nobody knows what they do. That is how networks become messy and harder to protect.
Segment your network where it makes sense
Not every system should sit in the same part of your network. Network segmentation helps separate different types of traffic, users and systems.
For example, you may want to separate guest Wi-Fi from company devices. You may also want to separate servers, finance systems, management tools or public-facing services from the rest of your internal network.
Some businesses use a DMZ, or demilitarised zone, for systems that need to communicate with the internet but should not have direct access to the internal network. This adds an extra layer between external traffic and sensitive business systems.
Segmentation is especially important if your business has remote users, public-facing applications, third-party access or older equipment that cannot easily be replaced.
If you are not sure whether your firewall rules and network design are doing what you think they are doing, network penetration testing can help identify weaknesses before attackers find them.
Do not treat the firewall as your only defence
A firewall matters, but it is not the whole answer. Modern attacks often involve email, stolen credentials, infected devices, cloud accounts and social engineering.
That is why your firewall should be part of a wider security setup. Your business should also consider endpoint protection, email filtering, multi-factor authentication, patching, backups and staff awareness.
For example, anti phishing support can help reduce the chance of users clicking suspicious links or sharing login details. Good endpoint protection can help detect harmful activity on laptops and desktops. Regular patching can close known vulnerabilities before they are exploited.
Your hardware also matters. Old routers, unsupported devices and poorly managed software can create unnecessary risk. Hardware and software support can help you choose and manage technology that fits your current security needs.
Keep firewall reviews simple and regular
Firewall security does not need to be overcomplicated. What matters is that it is reviewed regularly and managed properly.
A simple review could include:
- Check whether unused firewall rules can be removed.
- Confirm that admin passwords are strong and unique.
- Review whether multi-factor authentication is enabled.
- Update firewall firmware and security patches.
- Check remote access settings.
- Review logs for unusual traffic or repeated blocked attempts.
- Confirm that public-facing services still need to be exposed.
- Check whether old users or admin accounts still exist.
- Review guest Wi-Fi and segmented networks.
- Document any changes clearly.
If your business operates across different offices or countries, firewall consistency becomes even more important. Global support and international projects can help businesses keep IT standards aligned across locations, while European IT support can help if your users or sites are spread across the UK and Europe.
Plan firewall changes carefully during migrations
Firewall security is often affected during wider IT changes. A move to Microsoft 365, a new cloud platform, a new office, a server replacement or a remote working project can all change the traffic your firewall needs to handle.
This is why security should be included early in any technology change. Do not wait until the end of a project to ask whether the firewall rules still make sense.
With properly planned IT migrations, you can review access, remove old rules and make sure your new setup is not carrying unnecessary risk from your old environment.
Take the next step
A secure corporate firewall is not about one clever setting. It is about sensible configuration, strong access control, regular review and making sure the firewall works alongside the rest of your IT security.
If your firewall has not been reviewed recently, now is a good time to check it. A short review today could help prevent a costly issue later, whether that cost comes from downtime, lost productivity, reputational damage or emergency recovery work.
If you want practical help reviewing your firewall, improving network security or building a stronger wider IT setup, contact Northern Star. Their team can help you understand where the risks are, what needs fixing first and how to strengthen your business without making IT harder than it needs to be.
