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Zenarmor Hardware Requirements for OPNsense Firewall

Due to the nature of deep packet analysis and detailed drill-down reporting functionality, Zenarmor (Sensei) requires more hardware resources than a standard L3-L4 firewall.


Starting from Sensei 1.5 release, you can offload your reporting database to an external system. This allows you to be able to run Zenarmor on systems with a constrained amount of RAM.

It is recommended that you check if your Ethernet adapter functions well with netmap.

CPU & Memory

Because the analytics module relies on Elasticsearch to process large amounts of data, the amount of the memory available in the system is crucial for the overall performance of Zenarmor.


If the number of active devices are more than 250 and the sustained WAN bandwidth is higher than 100 Mbps, we do not recommend deploying Zenarmor as a virtual guest since resources in virtual environments are generally shared between guest systems.

Below is the recommended minimum hardware requirements for Zenarmor based on the number of devices and the amount of sustained bandwidth.

We recommend at least dual core (preferable 4 core if you also host database on the firewall) cpu system.


Single core cpu score is more important than having lots of cpu cores; for that, a Quad Core i7 PC system is more likely to perform better than a 12-core intel xeon server system.**

Active DevicesMaximum WAN BandwidthMinimum MemoryMinimum CPU
0 - 25200 Mbps4 GBA Dual-Core CPU (x86_64 compatible, single core PassMark score of 200) Note: Deciso A10s and AMD G-SERIES SOC GX Series, Protectli/Qotom Celeron J Series are compatible
25-100500 Mbps 10 Kpps4 GBIntel Dual-Core i3 2.0 GHz (2 Cores, 4 Threads) or equivalent
100-2501 Gbps 20 Kpps8 GBIntel Dual-Core i5 2.2 GHz (2 Cores, 4 Threads) or equivalent
250-10001-2 Gbps 40 Kpps16 GBIntel Dual-Core i5 3.20 GHz (2 Cores, 4 Threads) or equivalent
1000-20001-2 Gbps32 GBIntel Quad-Core i7 3.40 GHz (4 Cores, 8 Threads) or equivalent
2000+1-2 Gbps64GBIntel Quad-Core i7 3.40 GHz (4 Cores, 8 Threads) or equivalent

Zenarmor requires at least 2 GB of memory. Installer will not continue if you have less than 2 GB of RAM. We recommend 4 GB memory to have an improved experience._

Ethernet Adapter

Zenarmor uses a FreeBSD subsystem called netmap(4) to access raw Ethernet frames. With FreeBSD 11 (OPNsense version <= 20.1) this software can be very particular in terms of proper driver compatibility.

Intel based adapters, particularly em(4) and igb(4), are observed to perform well in terms of stability and performance.

Sunny Valley Networks is sponsoring developments on this project so you can expect netmap(4) will better support a wide range of Ethernet drivers.

Reporting & Disk Space

Zenarmor uses Elasticsearch or MongoDB as its backend to store large data sets. Please allow at least 5 MB of disk space per hour per megabit/second throughput.

If you're running a 100 Mbps link (about 100 devices) which is quite active during the daytime and idle rest of the day, you may calculate the space needed as follows:

  • 5 MB x 12 hours x 100 Mbps = 6 GB per day.
  • 6 GB x 7 days a week = 42 GB per week.
  • 2 x 4 weeks a month = 164 GB per month

According to the reports we receive from Zenarmor users; Elasticsearch seems to be a better alternative as the backend database. If you're using Mongodb backend and experiencing problems, it might be wise to switch to the Elasticsearch backend. You'll need at least 8GB of RAM to be able run ES along with Zenarmor.