Security groups let you control network access to instances by applying network rules to instances associated with a group.
To create a security group:
Enter the following command:
euca-add-group -d <description> <group_name>
Note
You can also create a security group you run an instance. Use the command with the option. Security group rules only apply to incoming traffic thus all outbound traffic is permitted.The following example creates a new security group named mygroup and described as newgroup .
euca-add-group -d "newgroup" mygroup