High Performance Tuning

Ubuntu Server

For best performance, we recommend starting with Ubuntu Server (no GUI) and adding our Security Onion packages as described in our ProductionDeployment guide.

Disable GUI

If you’re unable to start with Ubuntu Server (no GUI) as recommended above, you can disable the GUI after the system is installed.

Best Practices

When you run Setup, make sure you choose Best Practices.

Disable Unnecessary Services

Disable any other unnecessary services. For example, to disable bluetooth:

sudo systemctl stop bluetooth.service
sudo systemctl disable bluetooth.service

CPU Affinity/Pinning

For best performance, CPU intensive processes like Zeek, Suricata, and Snort should be pinned to specific CPUs. In most cases, you’ll want to pin sniffing processes to the same CPU that your sniffing NIC is bound to.

Snort Performance

Suricata Performance

Zeek Performance


Check your sniffing interfaces to see if they have Receive Side Scaling (RSS) queues. If so, you may need to reduce to 1:


If you have plenty of RAM, disable swap altogether.

Use hdparm to gather drive statistics and alter settings, as described here:

vm.dirty_ratio is the maximum amount of system memory that can be filled with dirty pages before everything must get committed to disk.

vm.dirty_background_ratio is the percentage of system memory that can be filled with “dirty” pages, or memory pages that still need to be written to disk – before the pdflush/flush/kdmflush background processes kick in to write it to disk.


You will want to make sure that each part of the pipeline is operating at maximum efficiency. Depending on your configuration, this may include syslog-ng, Logstash, Redis, and Elasticsearch. For really high volume logs, you may want to consider the LOGSTASH_MINIMAL option.