Last week, we released Security Onion 3.1.0:
https://blog.securityonion.net/2026/05/security-onion-310-now-available-with.htmlToday we are releasing a hotfix which resolves two known issues in that release:
https://docs.securityonion.net/en/3/main/release-notes/We've been offering our Security Onion documentation in book form on Amazon for a few years and it's now been updated for the recently released Security Onion 3.1!
Proceeds go to the Rural Technology Fund!
This edition has been updated for Security Onion 3.1 and includes a 20% discount code for our on-demand training and certification!
This book covers the following Security Onion topics:
Q&A
What is the difference between this book and the online documentation?
This book is the online documentation formatted specifically for print. Proceeds go to the Rural Technology Fund! Finally, the printed book includes a 20% discount code for our on-demand training and certification.
Who should get this book?
You should get this book if you work on airgap networks or simply want a portable reference that doesn't require an Internet connection or batteries! Also anyone who wants to donate to a worthy cause like Rural Technology Fund!
What is the difference between this edition and the previous edition?
This edition has been updated for Security Onion 3.1!
Where do we get it?
https://securityonion.com/book
Security Onion 3.1.0 is now available and includes new features, updated components, and many quality of life improvements!
https://docs.securityonion.net/en/3/main/release-notes#changes
Known Issues
For a list of known issues, please see:
https://docs.securityonion.net/en/3/main/release-notes#known-issues
About Security Onion
Security Onion is a free and open platform built by defenders for defenders. It includes network visibility, host visibility, intrusion detection honeypots, log management, and case management.
For network visibility, we offer signature based detection via Suricata, rich protocol metadata and file extraction using your choice of either Zeek or Suricata, full packet capture, and file analysis. For host visibility, we offer the Elastic Agent which provides data collection, live queries via osquery, and centralized management using Elastic Fleet. Intrusion detection honeypots based on OpenCanary can be added to your deployment for even more enterprise visibility. All of these logs flow into Elasticsearch and we’ve built our own user interfaces for alerts, dashboards, threat hunting, case management, and grid management.
Security Onion has been downloaded over 2 million times and is being used by security teams around the world to monitor and defend their enterprises. Our easy-to-use Setup wizard allows you to build a distributed grid for your enterprise in minutes!
Documentation
You can find our online documentation here:
https://docs.securityonion.net/en/3/main/
Documentation is always a work in progress. If you find documentation that needs to be updated, please let us know as described in the Feedback section below.
New Installations
If this is your first time installing Security Onion, then we highly recommend starting with an IMPORT installation as shown at:
https://docs.securityonion.net/en/3/main/first-time-users
Once you’re comfortable with your IMPORT installation, then you can move on to more advanced installations as shown at:
https://docs.securityonion.net/en/3/main/architecture
Existing 2.4 Installations
Security Onion 3 only supports Oracle Linux 9. If you are running Security Onion 2.4 on some other unsupported distro, then you will need to perform a fresh installation of Security Onion 3.
If you have an existing Security Onion 2.4 installation running on Oracle Linux 9, you can upgrade to Security Onion 3 as shown here:
https://docs.securityonion.net/en/3/main/appendix
Before updating your production deployment, we highly recommend testing the upgrade process on a test deployment that closely matches your production deployment if possible.
2.4 EOL
Security Onion 2.4 will reach End Of Life (EOL) on October 1, 2026. If you are a Security Onion Solutions customer, please feel free to reach out to our Support team for assistance.
Thanks
Lots of love went into this release!
Special thanks to all our folks working so hard to make this release happen!
Questions, Problems, and Feedback
If you have any questions or problems, please create a new Discussion at:
https://securityonion.net/discuss
Security Onion Pro
Security Onion Pro includes many enterprise features that folks have been asking for:
You can read more about these enterprise features at:
https://securityonion.com/proTraining
Need training? Start with our free Security Onion Essentials training and then take a look at some of our other official Security Onion training!
https://securityonion.net/training
Security Onion Solutions Hardware Appliances
We know Security Onion's hardware needs, and our appliances are the perfect match for the platform. Leave the hardware research, testing, and support to us, so you can focus on what's important for your organization. Not only will you have confidence that your Security Onion deployment is running on the best-suited hardware, you will also be supporting future development and maintenance of the Security Onion project!
https://securityonion.com/hardware
Cloud Installations
For new Security Onion 2 installations in the cloud, this new version will soon be available on the AWS, Azure, and GCP marketplaces!
AWS Marketplace and Documentation:
https://securityonion.net/aws/
https://docs.securityonion.net/en/3/main/cloud-amazon
Azure Marketplace and documentation:
https://securityonion.net/azure
https://docs.securityonion.net/en/3/main/cloud-azure
GCP Marketplace and documentation:
https://securityonion.net/google
This year's Security Onion Conference is currently scheduled to be held in person in Augusta, GA on Friday, October 23, 2026. Registration will open August 7.
CFP
Want to speak at Security Onion Conference? We want to hear from you!
How are you...
...using Security Onion to find evil?
...handling lots of traffic and logs using Security Onion?
...integrating Security Onion with other technologies?
...automating common tasks with your own scripts?
...using Security Onion in a unique way?
Each talk should be 45 minutes, including time for questions. Submit your talk here:
https://securityonion.net/cfp
Schedule
May 18 - CFP open
July 13 - CFP closes
August 6 - Speakers selected and notified
August 6 - Registration opens at Noon Eastern Time
October 19 through October 22 - Security Onion 4-day training in Augusta
October 23 - Security Onion Conference
October 24 - BSidesAugusta
Previous Conferences
Want to see talks from previous Security Onion Conferences?
https://securityonion.net/conf
There is a new local privilege escalation called Dirty Frag (CVE-2026-43284):
Updated kernel packages should be coming soon to resolve this issue. If you can't wait until updated kernels are released and need to apply a temporary mitigation, please see the Mitigation section of the article above and also:
https://github.com/V4bel/dirtyfrag#mitigation
A flaw was found in the Linux kernel that allows for local privilege escalation:
https://access.redhat.com/security/cve/cve-2026-31431
Updated kernel packages should be coming soon to resolve this issue.
UPDATE 2026/05/04 Oracle has released an updated UEK kernel (5.15.0-319.201.4.4) to address this vulnerability (https://linux.oracle.com/errata/ELSA-2026-50253.html). Assuming you're running Security Onion on Oracle 9 with the Oracle UEK kernel, you can update to this new kernel with a standard soup (https://docs.securityonion.net/en/3/main/soup/) followed by a reboot.
If you can't wait until updated kernels are released and need to apply a temporary mitigation, you can run the following command and then reboot:
sudo grubby --update-kernel=ALL --args="initcall_blacklist=algif_aead_init"
After updated kernels are released, that temporary mitigation can be reverted by running the following command and then rebooting:
sudo grubby --update-kernel=ALL --remove-args="initcall_blacklist=algif_aead_init"
