Zenarmor (Sensei): Hardware Requirements

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


With the Sensei 1.5 release, you can offload your reporting database to an external system. This allows you 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 memory available in the system is crucial for the overall performance of Zenarmor.


If the number of active devices is more than 500 and the sustained WAN bandwidth is higher than 500 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:

# Active Devices

Maximum WAN Bandwidth

Minimum Memory

Minimum CPU


300 Mbps

1 GB

A Dual-Core CPU (x86_64 compatible, single core PassMark score of 200)


500 Mbps - 10 Kpps

4 GB

Intel Dual-Core i3 2.0 GHz (2 Cores, 4 Threads) or equivalent


1 Gbps - 20 Kpps

8 GB

Intel Dual-Core i5 2.2 GHz (2 Cores, 4 Threads) or equivalent


1-2 Gbps 40 Kpps

16 GB

Intel Dual-Core i5 3.20 GHz (2 Cores, 4 Threads) or equivalent


1-2 Gbps

32 GB

Intel Quad-Core i7 3.40 GHz (4 Cores, 8 Threads) or equivalent


2-4.5 Gbps

64 GB

Intel Quad-Core i9 3.0 GHz (24 Cores, 48 Threads) or equivalent


Zenarmor requires at least 1 GB of memory. The installer will not continue if you have less than 1 GB of RAM. We recommend 8 GB memory to have an exceptional reporting experience with the elasticsearch database.

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.

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 users) that is quite active during the daytime and idle the 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.
42 x 4 weeks a month = 168 GB per month.

As of version 0.7.0, Zenarmor expires old report data to free up disk space for the most recent data based on the configured number of days of history to keep.