EC2 Security Groups
An EC2 security group is essentially a set of firewall rules that can be applied to multiple EC2 instances. Each group defines a list of ports and optionally hosts that are allowed to connect to instances using that group. Groups can also grant access to members of other groups, thus allowing communication between EC2 systems.

This page lists all security groups that are associated with your EC2 accounts. Initially there will be only a single default group, but if you have created any instances there will also be a virtualmin group which allows access to ports used for web and mail hosting.

To edit an existing group, just click on its name. To remove one or more groups that are not being used, select the checkboxes next to them and click the Delete button.