Doug Burks edited this page Nov 30, 2018 · 95 revisions

Install / Update / Upgrade
Users / Passwords
Support / Help
Error messages
IPS/IDS engines
Security Onion internals
sostat output

Install / Update / Upgrade

Why won't the ISO image boot on my machine?


What's the recommended procedure for installing Security Onion?

Installation Procedure

Why does the installer crash when selecting a non-English language?

We only support the English language at this time:

Why can't I see the Continue button on the Keyboard Layout screen of the installer?

The Keyboard Layout screen may be larger than your screen resolution and so the Continue button may be off the screen to the right like this:
You can simply slide the window over until you see the Continue button. For more information, please see:

How do I install Security Onion updates?

Upgrade Procedure

Why do I get Snort/Suricata/Bro errors after upgrading the kernel and pfring packages?


I recently updated barnyard and now I'm not getting any Snort alerts.

Some users running the Snort engine with the Snort Subscriber (Talos) ruleset are experiencing barnyard2 failing with errors like Returned signature_id is not equal to updated signature_id. This is due to some wrong entries in the database left by the previous version of barnyard2. One of the barnyard2 developers wrote a MySQL script to fix these entries and I've packaged it into a shell script called so-snorby-fix-sigs and included it in the rule-update package. If you're running the Snort engine with the Snort Subscriber (Talos) ruleset, please run so-snorby-fix-sigs and follow the directions (including shutting down all barnyard2 instances before proceeding with the database changes).

What do I need to do if I'm behind a proxy?

Proxy Configuration

Ubuntu is saying that my kernel has reached EOL (End Of Life). Should I update to the newer HWE stack?

Please see our HWE page.

Why does my VMware image rename eth0 to eth1?

Usually this happens when you clone a VM. VMware asks if you moved it or copied it. If you select "copied", it will change the MAC address to avoid duplication. At the next boot, Ubuntu's udev will see a new MAC address and create a new network interface (eth1). To fix this:

sudo rm /etc/udev/rules.d/70-persistent-net.rules
sudo reboot

How do I get Security Onion to recognize more than 4GB of RAM?

If you have a 64-bit machine, use our 64-bit ISO image or use a 64-bit version of Ubuntu.

Can I run Security Onion on Raspberry Pi or some other non-x86 box?

No, we only support x86 and x86-64 architectures. Please see the hardware page.

What's the difference between a server and a sensor?

Definition: A physical or virtual machine running the Security Onion operating system.

Definition: A set of processes that receive data from sensors and allow analysts to see and investigate that data. The set of processes includes sguild, mysql, and optionally the Elastic stack (Elasticsearch, Logstash, Kibana) and Curator. The server is also responsible for ruleset management.
Naming convention: The collection of server processes has a server name separate from the hostname of the box. Security Onion always sets the server name to securityonion.
Configuration files: /etc/nsm/securityonion/
Controlled by: /usr/sbin/nsm_server

server box
Definition: A machine running the server processes. May optionally be running sensor processes.
Example 1: User runs Quick Setup on machine with hostname securityonion and two ethernet interfaces. Setup creates a server and two sensors (securityonion-eth0 and securityonion-eth1).
Example 2: User runs Advanced Setup and chooses Server. Setup creates a server only (no sensor processes).

Definition: A set of processes listening on a network interface. The set of processes currently includes Snort/Suricata, netsniff-ng, and bro (although this is in constant flux as we add new capabilities and find better tools for existing capabilities).
Naming convention: $HOSTNAME-$INTERFACE
Configuration files: /etc/nsm/$HOSTNAME-$INTERFACE/
Example: sensor1-eth0
Controlled by: /usr/sbin/nsm_sensor

sensor box
Definition: A machine having one or more sensors that transmit to a central server. Does not run server processes. Pulls ruleset from server box. (In some contexts, I refer to this a slave pulling rules from the master.)
Example: A machine named sensor1 having sensors sensor1-eth0 and sensor1-eth1.

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Users / Passwords

What is the password for root/mysql/Sguil/Squert/Kibana?


How do I add a new user account for logging into Sguil/Squert/Kibana?

Adding Sguil accounts

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Support / Help

Where do I send questions/problems/suggestions?

security-onion Google Group

I submitted a message to the security-onion Google Group. Why isn't it showing up?


Is commercial support available for Security Onion?

Yes, please see:

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Error messages

Why does rule-update fail with Error 400 when running behind a proxy?

Please see

Why does rule-update fail with an error like "Error 404 when fetching"?

The Snort Community ruleset has moved to a different URL. You can run the following command to update the Snort Community URL in pulledpork.conf:

sudo sed -i 's\rule_url=|community-rules.tar.gz|Community\rule_url=|community-rules.tar.gz|Community\g' /etc/nsm/pulledpork/pulledpork.conf

For more information, please see:

Why does soup fail with an error message like "find: `/usr/lib/python2.7/dist-packages/salt/': No such file or directory"?

This is a bug in the salt packages that can manifest when skipping salt versions. Resolve with the following:

sudo mkdir -p /usr/lib/python2.7/dist-packages/salt/
sudo apt-get -f install
sudo soup

Why does barnyard2 keep failing with errors like "Returned signature_id is not equal to updated signature_id"?

Please see:

I just updated Snort and it's now saying 'ERROR: The dynamic detection library "/usr/local/lib/snort_dynamicrules/" version 1.0 compiled with dynamic engine library version 2.1 isn't compatible with the current dynamic engine library "/usr/lib/snort_dynamicengine/" version 2.4.'

Run the following:

sudo rule-update

For more information, please see:

I get periodic MySQL crashes and/or error code 24 "out of resources" when searching in Sguil. How do I fix that?

Recent versions of Setup should set MySQL's open-files-limit to 90000 to avoid this problem:

If you ran Setup before February 2014, you can set this manually as follows.

First, stop sguil and mysql:

sudo so-sguild-stop
sudo service mysql stop

Next, edit /etc/mysql/my.cnf and add the following in the mysqld section (please use hyphens not underscores):

open-files-limit        = 90000

Finally, start mysql and sguil:

sudo service mysql start
sudo so-sguild-start

For more information, please see:

Barnyard2 is failing with an error like "ERROR: sguil: Expected Confirm 13324 and got: Failed to insert 13324: mysqlexec/db server: Duplicate entry '9-13324' for key 'PRIMARY'". How do I fix this?

Sometimes, just restarting Barnyard will clear this up:

sudo so-barnyard-restart

Other times, restarting Sguild and then restarting Barnyard will clear it up:

sudo so-sguild-restart
sudo so-sensor-restart --only-barnyard2

If that doesn't work, then try also restarting mysql:

sudo service mysql restart
sudo so-sguild-restart
sudo so-sensor-restart --only-barnyard2

If that still doesn't fix it, you may have to perform MySQL surgery on the database securityonion_db as described in the Sguil FAQ:

Why do I get the following error when starting Sguil?

Application initialization failed: no display name and no $DISPLAY environment variable
ERROR: Cannot fine the Iwidgets extension.
The iwidgets package is part of the incr tcl extension and is
available as a port/package most systems.
See for more info.

This is related to this question. See tcl.

Why does Snort segfault every day at 7:01 AM?

7:01 AM is the time of the daily PulledPork rules update. If you're running Snort with the Snort Subscriber (Talos) ruleset, this includes updating the SO rules. There is a known issue when running Snort with the Snort Subscriber (Talos) ruleset and updating the SO rules:
After updating the rules, Snort is restarted, and the segfault occurs in the OLD instance of Snort (not the NEW instance). Therefore, the segfault is merely a nuisance log entry and can safely be ignored.

Why does the pcap_agent log show "Error: can't read logFile: no such variable"?

This usually means that there is an unexpected file in the dailylogs directory. Run the following:

ls /nsm/sensor_data/*/dailylogs/

You should see a bunch of date stamped directories and you may see some extraneous files. Remove any extraneous files and restart pcap_agent:

sudo so-pcap-agent-restart

I'm running the Security Onion 12.04.5 ISO image and Chromium crashes and/or displays a black screen.

This is a known issue with certain versions of VMware. You can either:

  • go into the VM configuration and disable 3D in the video adapter
  • upgrade the VM hardware level (may require upgrading to a new version of VMware)

Why does Bro log Failed to open GeoIP database and Fell back to GeoIP Country database?

The GeoIP CITY database is not free and thus we cannot include it in the distro. Bro fails to find it and falls back to the GeoIP COUNTRY database (which is free). As long as you are seeing some country codes in your conn.log, then everything should be fine. If you really need the CITY database, see this thread for some options:

Why does soup tell me I need a Secure Boot key?

Since Ubuntu kernel 4.4.0-20, the EFI_SECURE_BOOT_SIG_ENFORCE kernel configuration has been enabled. This prevents the loading of unsigned third party modules if UEFI Secure Boot is enabled.

An example of this can be found here:

If Secure Boot is enabled for your machine, you can disable it, following the steps found here:

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IPS/IDS engines

I'm currently running Snort. How do I switch to Suricata?

Please note that, if you're running the Snort Talos ruleset, Snort Shared Object rules will not load in Suricata. Most folks who choose the Suricata engine choose to run the Emerging Threats ruleset.

sudo so-sensor-stop
sudo sed -i 's|ENGINE=snort|ENGINE=suricata|g' /etc/nsm/securityonion.conf
sudo rule-update
sudo so-sensor-start

I'm currently running Suricata. How do I switch to Snort?

sudo so-sensor-stop
sudo sed -i 's|ENGINE=suricata|ENGINE=snort|g' /etc/nsm/securityonion.conf
sudo rule-update
sudo so-sensor-start

Can Security Onion run in IPS mode?

Running Security Onion as an IPS requires manual configuration and is not supported.
I talked about this on the Packet Pushers podcast:

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Security Onion internals

Where can I read more about the tools contained within Security Onion?


What's the directory structure of /nsm?

/nsm Directory Structure

Why does Security Onion use UTC?

UTC and Time Zones

Why are the timestamps in Kibana not in UTC?

UTC and Time Zones

Why is my disk filling up?

Sguil uses netsniff-ng to record full packet captures to disk. These pcaps are stored in nsm/sensor_data/$HOSTNAME-$INTERFACE/dailylogs/. /etc/cron.d/sensor-clean is a cronjob that runs every minute that should delete old pcaps when the disk reaches your defined disk usage threshold (90% by default). It's important to properly size your disk storage so that you avoid filling the disk to 100% between purges.

I just rebooted and it looks like the services aren't starting automatically.

/etc/init/securityonion.conf waits 60 seconds after boot to ensure network interfaces are fully initialized before starting services.

Why do apt-get and the Update Manager show tcl8.5 as held back?


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What do I need to tune if I'm monitoring VLAN tagged traffic?

VLAN Traffic

How do I configure email for alerting and reporting?


How do I configure a BPF for Snort/Suricata/Bro/netsniff-ng/prads?


How do I filter traffic?


How do I exclude traffic?


What are the default firewall settings and how do I change them?


What do I need to modify in order to have the log files stored on a different mount point?

Adding a New Disk for /nsm

How do I disable the graphical Network Manager and configuring networking from the command line?

Network Configuration

How do I enable/disable processes?

Disabling Processes

I disabled some Sguil agents but they still appear in Sguil's Agent Status tab.

Disabling Processes

What can I do to decrease the size of my securityonion_db (sguild) MySQL database?

You can lower the DAYSTOKEEP setting in /etc/nsm/securityonion.conf.
Also see UNCAT_MAX:

How do I change the fonts in the Sguil client?

In the Sguil client, click the File menu and then go to Change Font. You can change both the Standard and Fixed fonts.

Can I be alerted when an interface stops receiving traffic?

Interface stops receiving traffic

How do I boot Security Onion to text mode (CLI instead of GUI)?

In /etc/default/grub, change this line:




Then run:

sudo update-grub

For more information, please see:

If you're doing a new installation, you can avoid this altogether by installing our packages on top of Ubuntu Server (minimal installation, no GUI) instead of using the Security Onion ISO image.

I'm running Security Onion in a VM and the screensaver is using lots of CPU. How do I change/disable the screensaver?

  1. Click Applications.
  2. Click Settings.
  3. Click Screensaver.
  4. Screensaver Preferences window appears. Click the Mode dropdown and select "Disable Screen Saver" or "Blank Screen Only".
  5. Close the Screensaver Preferences window.

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sostat output

What does it mean if sostat show a high number of Sguil Uncategorized Events?

Sguild has to load uncategorized events into memory when it starts and it won't accept connections until that's complete.
You can either:

  • wait for sguild to start up (may take a LONG time), then log into Sguil, and F8 LOTS of events
  • stop sguild
sudo so-sguild-stop

and manually categorize events using mysql
lower your DAYSTOKEEP setting in /etc/nsm/securityonion.conf and run

sudo sguil-db-purge

To keep Uncategorized Events from getting too high, you should log into Sguil/Squert on a daily/weekly basis and categorize events.

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Where can I find the version information for Security Onion?

With regard to Security Onion 16.04, if the machine was built with the Security Onion 16.04 ISO image, version information can be found in /etc/PinguyBuilder.conf.

Where can I find interesting pcaps to replay?


Why is Security Onion connecting to an IP address on the Internet over port 123?


Should I backup my Security Onion box?

Network Security Monitoring as a whole is considered "best effort". It is not a "mission critical" resource like a file server or web server. Since we're dealing with "big data" (potentially terabytes of full packet capture), backups would be prohibitively expensive. Most organizations don't do any backups and instead just rebuild boxes when necessary.

How can I add and test local rules?

Adding local rules and testing them with scapy

Where can I get the source code?

You can download the full source code for any of our packages like this:

apt-get source PACKAGE-NAME

where PACKAGE-NAME is usually something like securityonion-snort. Here's a list of all of our packages:

How can I remote control my Security Onion box?

A few options:

  • "ssh -X" - any program started in the SSH session will be displayed on your local desktop (requires a local X server)
  • xrdp - sudo apt-get install xrdp - requires an rdp client
  • You can use FreeNX but we don't recommend or support it

Why isn't Squert showing GeoIP data properly?

If the Squert map is not showing the country for IPs, try running the following:

sudo /usr/bin/php -e /var/www/so/squert/.inc/ip2c.php 0'/

Why do I get segfaults when booting on VMware ESX?

This is a known issue with Ubuntu 10.04 and ESXi 4.1 and is unrelated to Security Onion. Please see:

How do I run ntopng on Security Onion?

Deploying NtopNG

How do I open rar files?

We're not allowed to redistribute the unrar plugin, so you'll need to install it manually:

sudo apt-get update
sudo apt-get install unrar

How do I perform "X" in Ubuntu?

Security Onion is based on Ubuntu, but we don't provide community support for the Ubuntu OS itself. If you have questions about Ubuntu, you should check the Ubuntu website, forums, and Google.

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