AWS SDK for .NET Documentation
CreateSecurityGroup Method (request)
AmazonAmazon.EC2AmazonEC2CreateSecurityGroup(CreateSecurityGroupRequest) Did this page help you?   Yes   No    Tell us about it...
Creates a new security group. Group names must be unique per account.
Declaration Syntax
Parameters
request (CreateSecurityGroupRequest)
Create Security Group request
Return Value
Create Security Group Response from the service
Remarks
Every instance is launched in a security group. If no security group is specified during launch, the instances are launched in the default security group. Instances within the same security group have unrestricted network access to each other. Instances will reject network access attempts from other instances in a different security group. As the owner of instances you can grant or revoke specific permissions using the AuthorizeSecurityGroupIngress and RevokeSecurityGroupIngress operations.
Exceptions

Assembly: AWSSDK (Module: AWSSDK) Version: 1.5.60.0 (1.5.60.0)