Before you start instances, configure access and security settings. For example, SSH access and ICMP access are not enabled by default.

Security groups
Enable users to ping and use SSH to connect to the instance. Security groups are sets of IP filter rules that define networking access and are applied to all instances in a project.
Key pairs
SSH credentials that are injected into an instance when it starts. To use key pair injection, the image that the instance is based on must contain the cloud-init package. Each project must have at least one key pair. If you generated a key pair with an external tool, you can import it into OpenStack. You can use the key pair for multiple instances that belong to a project.
Floating IPs
When you create an instance in OpenStack, it is assigned a fixed IP address in the network. This IP address is permanently associated with the instance until the instance is terminated. You can also attach to an instance a floating IP address whose association can be modified.