Defined in github.com/aws/aws-sdk-go/service/ec2/api.go
[EC2-Classic, default VPC] The name of the source security group. You can't specify this parameter in combination with the following parameters: the CIDR IP address range, the start of the port range, the IP protocol, and the end of the port range. For EC2-VPC, the source security group must be in the same VPC. To revoke a specific rule for an IP protocol and port range, use a set of IP permissions instead.