Security groups are firewalls for your instances, and they're mandatory in our cloud environment. The firewall actually exists on the nova-compute host that is running the instance and not in the instance itself. They allow us to protect our hosts by restricting and allowing access and also protect our instances from other users' instances running on the same hosts.
To begin with, ensure you're logged in to your Ubuntu client that has access to the euca2ools or Nova Client tools. These packages can be installed using the following commands:
sudo apt-get update sudo apt-get install euca2ools python-novaclient
The following sections describe how to create and modify security groups in our OpenStack ...