Security Groups
A security group is a set of network access rules that control incoming and outgoing traffic to Virtual Machines assigned to this group. With security group rules, you can specify the type and direction of traffic that is allowed access to a virtual interface port. Traffic that does not satisfy any rule is dropped.
For each project, the default security group is automatically created in the compute cluster. This group allows all traffic on all ports for all protocols and cannot be deleted. When you attach a network interface to a VM, the interface is associated with the default security group, unless you explicitly select a custom security group.
You can assign one or more security groups to both new and existing virtual machines.When you add or remove rules in security groups, the changes are enforced at runtime.