Creating a Security Group with aws ec2 create-security-group

When you need a new set of traffic rules, use aws ec2 create-security-group. It creates a security group.

The syntax is aws ec2 create-security-group --group-name name --description description. A freshly created group carries no rules at all.

Running aws ec2 create-security-group --group-name web-sg --description "web servers" creates the group and returns its GroupId.

A common stumble is creating the group and forgetting to add the inbound rules — creating it and configuring it are two separate steps.

In real work, separate groups per purpose (web servers, databases) allow each to permit only the minimum traffic required.