Airgap

Security Onion is commited to allowing users to run a full install on networks that do not have Internet access. Starting in 2.x RC3, users will see an option to specify that the install is airgapped. The installer will then make the appropriate modifications to make this work properly.

Key Differences

By selecting Airgap as an install option, a couple of things happen that are different than a normal install with Internet access. First, all CentOS repos are removed and replaced with a new repo that runs on the manager. During the install, all of the necessary RPMs are copied from the ISO to a new repo located in /nsm/repo/. All devices in the grid will now use this repo for updates to packages. Another difference is the latest ET Open rules from Emerging Threats are copied to /nsm/repo/rules/ so that the manager can access them. This allows users to use the standard SO process for managing SIDS etc. Finally, yara rules for Strelka are copied to /nsm/repo/rules/strelka/ so that Strelka has the latest and greatest rules for static file analysis.

Updating

Starting in version 2.3, soup will automatically detect that you are upgrading an airgap install and will ask for the location of the upgrade disk. This can be done by burning the disk and putting it in the DVD drive, burning a USB stick like any standard ISO, or simply copying the ISO file to the airgapped manager.

Updating from RC3

Note

If upgrading from RC3 there is an extra step that needs to take place to copy over the proper version of soup in order to complete the update. To accomplish this you need to run the following commands.

  • Create a temp directory:

    mkdir -p /tmp/sotemp
    
  • If using a DVD with the image burned to it:

    sudo mount /dev/cdrom /tmp/sotemp
    

    Otherwise, if using an ISO file:

    sudo mount -t iso9660 -o loop /home/user/securityonion-2.3.0.iso /tmp/sotemp
    
  • Copy the new version of soup:

    sudo cp /tmp/sotemp/SecurityOnion/salt/common/tools/sbin/soup /opt/so/saltstack/default/salt/common/tools/sbin/
    
  • Update Salt:

    sudo salt-call state.apply common
    
  • Unmount the temp directory:

    sudo umount /tmp/sotemp
    
  • Run the new version of soup

    sudo soup