# Create a security group to support EFA communications
<a name="working-with_networking_efa_create-sg"></a>

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#### [ AWS CLI ]

You can use the following AWS CLI command to create a security group that supports EFA. The command outputs a security group ID. Make the following replacements:
+ `region-code` – Specify the AWS Region where you use AWS PCS, such as `us-east-1`.
+ `vpc-id` – Specify the ID of the VPC that you use for AWS PCS.
+ `efa-group-name` – Provide your chosen name for the security group.

```
aws ec2 create-security-group \
    --group-name efa-group-name \
    --description "Security group to enable EFA traffic" \
    --vpc-id vpc-id \
    --region region-code
```

Use the following commands to attach inbound and outbound security group rules. Make the following replacement: 
+ `efa-secgroup-id` – Provide the ID of the EFA security group you just created. 

```
aws ec2 authorize-security-group-ingress \
    --group-id efa-secgroup-id \
    --protocol -1 \
    --source-group efa-secgroup-id
    
aws ec2 authorize-security-group-egress \
    --group-id efa-secgroup-id \
    --protocol -1 \
    --source-group efa-secgroup-id
```

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#### [ CloudFormation template ]

You can use a CloudFormation template to create a security group that supports EFA. Download the template from the following URL, then upload it into the [AWS CloudFormation console](https://console.aws.amazon.com/cloudformation). 

```
https://aws-hpc-recipes.s3.amazonaws.com/main/recipes/pcs/enable_efa/assets/efa-sg.yaml
```

With the template open in the AWS CloudFormation console, enter the following options.
+ Under **Provide a stack name**
  + Under **Stack name**, enter a name such as `efa-sg-stack`.
+ Under **Parameters**
  + Under **SecurityGroupName**, enter a name such as `efa-sg`.
  + Under **VPC**, select the VPC where you will use AWS PCS.

Finish creating the CloudFormation stack and monitor its status. When it reaches `CREATE_COMPLETE` the EFA security group is ready for use. 

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