PostInstallation

Verify services are running:
sudo service nsm status

If any services are not running, try starting them:
sudo service nsm start

Tuning / Miscellaneous

• Are you monitoring network traffic that has VLAN tags? If so, take a look at our VLAN page.

• If you’re monitoring IP address ranges other than private RFC1918 address space (192.168.0.0/16, 10.0.0.0/8, 172.16.0.0/12), you should update your sensor configuration with the correct IP ranges. Sensor configuration files can be found in /etc/nsm/$HOSTNAME-$INTERFACE/. Modify either snort.conf or suricata.yaml (depending on which IDS engine you chose during sosetup) and update the HOME_NET variable. (As of securityonion-setup - 20120912-0ubuntu0securityonion222, Setup should automatically ask you for HOME_NET and configure these for you.) You may also want to consider updating the EXTERNAL_NET variable. If you're runnning prads (you're probably not), then update the home_nets variable in prads.conf. Then update Bro’s network configuration in /opt/bro/etc/networks.cfg. Restart the sensor processes:
  sudo nsm_sensor_ps-restart

• If you have Internet access, create an IDS alert by typing the following at a terminal:
  curl http://testmyids.com

• As of securityonion-setup - 20120912-0ubuntu0securityonion201, Setup now defaults to only opening port 22 in the firewall. If you need to connect OSSEC agents, syslog devices, or analyst VMs, you can run the new so-allow utility which will walk you through creating firewall rules to allow these devices to connect. For more information, please see the firewall page.
  

• Full-time analysts should install Security Onion in a VM on their workstation (run through the Ubuntu installer, but do not run our Setup wizard). This gives you a local copy of Wireshark, NetworkMiner, and our customized Sguil client. Launch the Sguil client and connect to the IP/hostname of your production Sguil sensor (you may need to run so-allow as described in the previous step). This allows you to investigate pcaps without fear of impacting your production server/sensors. To change the resolution of your Security Onion VM, install the Virtual Tools for your virtualization solution or use xrandr. For a list of available screen resolutions, simply execute “xrandr”. To set the screen resolution (replace W and H with the actual Width and Height desired):
  xrandr -s WxH

• Login to Sguil and review your IDS alerts. Squert and ELSA can be accessed by visiting https://server/ for additional in-depth analysis.
  

Run the following to see how your sensor is coping with the load. You should check this on a daily basis to make sure your sensor is not dropping packets. Consider adding it to a cronjob and having it emailed to you (see the “configure email” link below).
`sudo sostat | less`

• Any IDS/NSM system needs to be tuned for the network it’s monitoring. Please see ManagingAlerts. You should only run the signatures you really care about.
  

• Review and categorize events every day with the goal being to categorize all events every day. Neglecting to do so will result in database/Sguil issues as the number of uncategorized events continues to increase on a daily basis.
  

• On the server running the Sguil database, set the DAYSTOKEEP variable in /etc/nsm/securityonion.conf to however many days you want to keep in your archive. The default is 30, but you may need to adjust it based on your organization’s detection/response policy and your available disk space.
  

• Modern versions of Setup automatically disable http_agent if you choose "Best Practices". However, if you chose Custom and then chose to enable http_agent, you should tune it using http_agent.conf. If you're running ELSA, you already have all the Bro HTTP logs available there, so you might want to disable http_agent to avoid duplicating those logs in the Sguil database:
  

# Terminate the running http_agent
sudo nsm_sensor_ps-stop --only-http-agent
# Disable http_agent
sudo sed -i 's|HTTP_AGENT_ENABLED="yes"|HTTP_AGENT_ENABLED="no"|g' /etc/nsm/*/sensor.conf

• Disable any unneeded sensor processes
  

• Tune the number of PF_RING instances for Snort/Suricata and Bro: PF_RING

Optional

• Optional: exclude unnecessary traffic from your monitoring using BPF.
  

• Optional: add new Sguil user accounts with the following:
  sudo nsm_server_user-add

• Optional, but highly recommended: configure Email for alerting and reporting.
  

• Optional: place /etc under version control. If your organization doesn't already have a standard version control tool, you can use bazaar, git, etckeeper:
  sudo apt-get install etckeeper

• Optional: need “remote desktop” access to your Security Onion sensor or server? We recommend SSH X-Forwarding as shown above, but if you want something more rdp-like, you can install FreeNX or xrdp (please note we do NOT support either of these):
  sudo apt-get install xrdp

Learn More

• Read more about the tools contained in Security Onion: Tools