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Perform following to modify the default security group network ACL for VPC:
Login to the AWS Management Console at https://console.aws.amazon.com.
Navigate to VPC console.
In the left pane, click Network ACLs.
Select the network ACL to be updated.
Click the Inbound Rules tab.
Click Edit inbound rules.
For the rule which allows ingress from 0.0.0.0/0 to port 22 either update the Source field to a range other than 0.0.0.0/0 or Click Delete to remove the inbound rule.
Click Save.
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