Firewall Architecture
A firewall is only as good as the policy on it. We design placement and failover, then build a rule set someone can still understand and safely change in three years.
Every firewall accumulates history
Rule sets grow. A vendor needed temporary access in 2019 and the rule is still there. An application was migrated and the old permit was never removed because nobody was certain what else depended on it. Something broke at 4pm on a Friday and a broad any-any rule fixed it, with a comment promising to tighten it later.
Individually, each of these is a reasonable decision made under pressure. Cumulatively they produce a policy nobody fully understands and therefore nobody will touch — which is the actual risk. A firewall that cannot be safely changed stops being a security control and becomes a liability with a support contract.
The other common pattern is a strong perimeter and nothing behind it. Traffic that crosses the edge moves freely, so a single compromised endpoint has reach across the estate. Modern threats do not politely stop at the boundary, and neither should enforcement.
What this covers
Placement and topology
Where enforcement actually belongs — perimeter, data centre, between internal zones, at the cloud edge — based on what needs separating rather than where the rack space happens to be. Routing and failover paths designed together, so a failover does not produce asymmetric traffic the firewall then drops.
High availability and resilience
Active-passive or active-active clustering with a tested failover, not an assumed one. We verify that state synchronizes, that sessions survive, and that the secondary can carry production load — because the moment you discover otherwise should not be during an outage.
Policy design and rule hygiene
A rule base organized so its intent is legible: grouped by function, documented at the rule rather than in a spreadsheet elsewhere, and structured so shadowed or redundant rules are visible. Where an existing policy needs rationalizing, we analyze real traffic before removing anything — the goal is a policy that can be maintained, and confidence is what makes that possible.
Internal segmentation
Enforcement between zones, not only at the edge. Payment environments, clinical systems, building controls, development networks and guest traffic each sit behind a boundary appropriate to their risk. This is usually where the most meaningful risk reduction is available, and it is usually the part that was skipped.
Inspection, logging and tuning
Intrusion prevention, application awareness and TLS inspection turned on deliberately — with the performance and privacy implications understood, not enabled wholesale because the licence includes them. Logging that produces evidence someone can actually use during an incident, tuned so real events are not buried under noise.
Migration and consolidation
Moving off end-of-support hardware, consolidating after an acquisition, or replacing a platform your team no longer wants to operate — with the policy translated and validated rather than blindly imported, and a cutover that has a rollback path.
How we engage
Consult
Review the current policy and topology: what is enforced, what is shadowed, what is unused, and where the gaps between zones are. You get findings and a prioritized plan — including the rules we would remove and why — whether or not we do the work.
Integrate
Design, build, and cut over: HA configured and failover tested, policy built or rationalized, inspection tuned, and the change staged so it can be reversed if the estate reacts unexpectedly.
Manage
Ongoing change control, firmware and signature lifecycle, and periodic policy review so the rule base does not quietly return to where it started. Change requests handled by someone who knows the environment rather than a queue.
Vendor-neutral by design
We design, deploy and manage across the major firewall platforms, and we will work with what you already own. Platform choice should follow the requirement — the throughput you need, the inspection you will actually enable, what integrates with your identity source, and what your team can operate confidently at 2am. See the vendors we work with.
Often the right answer is that the hardware is capable and the policy is the problem. A rationalization engagement costs a fraction of a platform migration, and we would rather do that than sell you a replacement you did not need.
Who this is for
- Organizations with a rule base nobody wants to change because the consequences are unclear.
- Estates with solid perimeter enforcement and nothing between internal zones.
- Teams facing an audit or compliance requirement that expects documented, justifiable firewall policy and segmentation evidence.
- Anyone running firewalls past end-of-support, or inheriting a platform after an acquisition or a departed administrator.
- Businesses that have bought advanced inspection features and never safely enabled them.
Ready to hand off the tech?
Book a free technology & security assessment. We'll map your gaps and give you a prioritized roadmap — no obligation, no jargon.