Before you launch an instance, you should add security group rules to 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 can be applied to all instances within a project. To do so, you either add rules to the default security group or group or add a new security group with rules.
...
This procedure enables SSH and ICMP (ping) access to instances. The rules apply can be applied to all instances within a given project, and should be set for every project unless there is a reason to prohibit SSH or ICMP access to the instances. This procedure can be adjusted as necessary to add additional security group rules to a project, if your cloud requires them.
...