Selecting a Firewall for Your SIEM Solution [Guide]

I’ve been working in cybersecurity for two decades, long before threat intelligence was a buzzword. Back in 1993 when I was a network admin, security was more straightforward. But that changed real fast. Remember the Slammer worm? I had seen firsthand how quickly a vulnerability could take down an entire network. Now the owner of my own security firm, I help businesses — particularly banks — keep safe as threats evolve so quickly. The first lines of defense against this? A solid firewall.

But a firewall isn’t sufficient on its own anymore. Half the picture is good, but if you don’t have a way of syphoning that data into a Security Information and Event Management (SIEM) solution, you just got all the right pieces but not a full puzzle. And that half could be the one that alerts you that someone is already in your network. Let’s dive in.

Why SIEM Integration Matters

You’ve got your firewall up and running. It blocks bad traffic, applies policies, and does its damnedest to keep the bad guys out. However, firewalls do not exist in a vacuum. They create logs — lots of them. And those logs tell a story.

The problem? If you’re sifting through those logs manually (or even worse — not looking at them at all), you’re leaving huge security blind spots. A SIEM solution ingests those logs and correlates them with data across your entire environment to aid in the detection of real threats.

This is why a properly integrated firewall and SIEM setup is really important:

• Centralized Visibility – No need to organize the logs across different security tools, everything is in one place.
• Identifying Security Threats in Real-Time – SIEM tools allow the definition of correlation rules to catch threats that don’t initiate a firewall alert.
• Forensics – After an event occurs you need logs to be able to understand what went wrong. That’s where a SIEM helps put the puzzle together.
• Compliance – If you’re in the banking, healthcare, or any other regulated industry, proper log management is often required by law.

Firewalls — The First Line of Defence

Firewalls work as the first line of defence for any network. They aren’t merely traffic blockers; they stop and watch the traffic. They also spit out logs chock-full of details such as:

• Source & Destination IPs – Who’s talking to whom?
• Port & Protocol Data – What type of data is moving where?
• Blocked Traffic Logs – Who’s knocking on the door (and should they be)?
• IPS Logs – Firewalls with IPS functionality also analyze incoming connection patterns for attack vectors.
• User Activity Logs – Particularly critical in zero-trust environments.

But here’s where many businesses fall short: Logs are useless without context. You need SIEM-friendly logs — structured, verbose, and meaningfully correlated.

How to Choose a Firewall With SIEM Support

Firewalls do not always cooperate well with a SIEM. Some generate minimal logs, while others take a whole lot of workarounds to not integrate at all. Here’s what to look out for:

1. Log Format Compatibility

   Your firewall should generate logs in structured formats (e.g. JSON or CEF (Common Event Format)). SIEM solutions love these. Steer clear of proprietary formats that require excessive customization.

2. Real-Time Log Forwarding

   Certain firewalls log in batches and send them all at once. That’s a problem. For an example of what a firewall with SIEM support looks like, it should:

   • Stream logs (real-time) over syslog and API.
   • Support secure transmission (encryption of logs protects against tampering).
   • Include some custom log filtering, so you’re not inundated with useless data.
3. Connects to External Databases and APIs with Deep Packet Inspection & Threat Intelligence Feeds

   Firewalls that only allow/block based on static rules are obsolete. Look for models that:

   • Perform Deep Packet Inspection (DPI) to have more fine-grained filtering.
   • Integrate threat intelligence feeds — this means your firewall is learning about emerging threats, not just responding to existing ones.
4. Built-in SIEM Connectors

   Certain next-gen firewalls might also have inbuilt connectors for SIEM tools such as Splunk, ArcSight, etc. If all the integrations take a ton of custom scripting — run.

Integrating the Fortinet SIEM with PJ Networks

Here’s the thing — I don’t recommend things I wouldn’t use myself. And outside of integrating hardware like firewalls for years, the SIEM compatibility is what separates Fortinet. We’ve implemented Fortigate firewalls across various financial institutions where angel visibility is a must, and the skin-integration is flawless.

Why?

• Fortinet doesn’t merely log the traffic; it enriches it. You have complete context on threats, users, and network behavior.
• Configurable Logging to avoid being buried in noise and focus on what matters.
• Built-in FortiSIEM integration saves time on configuration and troubleshooting.

Recently we have transformed three banks to zero-trust models with Fortinet’s firewall + SIEM stack. During testing, we found attempts to infiltrate their networks with compromised third-party credentials — something their former firewall didn’t even flag to the extent of badging them. That illustrates the difference of good SIEM integration.

Quick Take

If you don’t have time, here’s what you need to know:

• A firewall creates important logs, but without SIEM analysis they are dead.
• Verify that your firewall supports real-time log forwarding in structured formats, as not all firewalls mesh well with SIEMs.
• We believe Fortinet firewalls are a good choice because SIEM tools are natively supported, which reduces deployment friction.

The flame of a poorly integrated firewall could allow the threat to slip through.

Conclusion

Firewalls are essential but not enough alone. It’s like having security cameras and nobody is monitoring the feed. A firewall without SIEM integration is just an expensive doorstop. And with the threats of today’s world changing by the minute, you can’t afford that blind spot.

If you are serious about security (you should be), then not only must your firewall support your SIEM, it must send the data needed — in real-time, in the right format, and at sufficient detail to detect real attacks.

Want assistance configuring firewall + SIEM integration? That’s exactly what I do. Let’s talk.