Alright, let's cut through the usual "suricata is great!" echo chamber. Everyone recommends the IDS/IPS plugins, but nobody talks about the operational reality of running them on OPNsense. The hype glosses over the tuning, the false positives, and the performance hit on your hardware.
So, let's talk about the actual plugins worth your time, with the caveats that the vendors and die-hard fans won't mention.
First, the obvious: **Suricata** (via os-suricata) is the heavyweight. It's powerful, but out-of-the-box it's a noisy beast that will flood you with alerts for every Windows update check. The real work isn't installing it; it's spending the next two weeks whitelisting your internal traffic patterns and tuning rule sets. If you're not prepared to do that, you've just installed a very expensive log generator. Also, enabling IPS mode on a busy gateway *will* impact throughput—don't believe anyone who says otherwise without stating their hardware specs.
For a slightly more manageable approach, **Zenarmor** (formerly Sensei) gets a lot of buzz. It's more user-friendly and does decent application-level visibility and filtering. The catch? The free version is limited. The subscription model is where they get you, and you're locking into their ecosystem. It's less of a pure IDS/IPS and more of a hybrid. Useful? Yes. But evaluate whether the subscription cost is justified over a well-tuned Suricata setup.
Then there's **CrowdSec**, which is interesting conceptually as a distributed IPS. The plugin is still a bit rough around the edges in my experience. It can be effective for blocking brute-force attacks and widespread scanners, but it's not a replacement for a full protocol analyzer like Suricata. Think of it as a supplement.
My take? There is no "best." It's a trade-off:
* Suricata for maximum control and no extra fees, but with a high tuning overhead.
* Zenarmor for a more polished, all-in-one experience, at the cost of potential vendor lock-in and recurring fees.
* CrowdSec for a modern, crowdsourced approach to blunt-force attacks, but not a complete solution.
I'm curious what others have actually *lived with* in production for more than six months. What's your false-positive headache level? What hardware did you need to throw at it to keep performance decent?
— skeptical but fair
I run OPNsense on a Dell R210 II with a Xeon E3 at our 30-person software shop, handling both office traffic and a small dev/test lab, where I've been managing Suricata in IPS mode for about two years and ran Zenarmor's free tier for a six-month trial.
1. **Target user and management overhead** - Suricata is a full-time project for anyone wanting it tuned right; I spent probably 40 hours over the first month just on whitelists and rule sensitivity. Zenarmor is closer to "set and forget" for SOHO use, with a dashboard that makes sense to non-network engineers.
2. **Real cost beyond the sticker** - Zenarmor's subscription starts around $99/year for home, but business pricing scales fast. Suricata is free, but your hidden cost is time; I'd value my tuning labor at several hundred dollars if I'd billed it. Also, Suricata on a busy gigabit link might need a hardware bump; my R210 II saw a 15-20% throughput drop with all rulesets enabled.
3. **Detection scope and false positives** - Suricata, with the ET Open ruleset, flagged endless noise from internal services like WSUS and cloud backups until I manually disabled dozens of rules. Zenarmor, being more application-aware, was quieter out of the gate but less granular on specific network-based threats.
4. **Performance impact with IPS active** - This is hardware dependent, but on my box (with a 4-core Xeon and 16GB RAM), enabling Suricata in IPS mode for a 500 Mbps link added about 3ms of latency under load. Zenarmor in filtering mode had a negligible latency hit but used more RAM consistently, around 2GB extra.
For a small business or a lab where you need visibility without becoming a full-time security analyst, I'd actually lean toward Zenarmor's free tier to start. If you're specifically looking to block known CVE exploits across your whole network and have the cycles to manage it, Suricata is the tool. To make it clean, tell us your upstream bandwidth and whether you have a dedicated staffer for weekly rule reviews.
Your point about valuing the tuning labor at several hundred dollars is the most accurate hidden cost breakdown I've seen. It's a classic Capex vs. Opex calculation for on-prem software.
If we run the numbers for a business, that 40-hour initial investment at a conservative $75/hour internal rate is a $3,000 sunk cost before Suricata even functions properly. Zenarmor's subscription, even at a few hundred per year, can become justifiable purely on labor savings, provided its detection meets your needs. The break-even point is surprisingly short.
I'd add one more cost dimension: the ongoing "management drift." After your initial tuning, any new internal service or significant change requires revisiting those Suricata rules, incurring more labor. Zenarmor's subscription theoretically includes the curation and updates to handle new protocols, which, while not perfect, does offload that continuous time cost.
Spreadsheets or it didn't happen.