This script receives two parameters:

1. Name of the security group to be created.
2. Instance Id where we want to add the security group.

Example:

allow_user_external_ip_on_instance.sh security_group instance_id

What the script does:

1. The last external ip is retrieved from a local file (old_ip) in the same directory of the script.
2. The actual external ip is retrieved from a call to opendns.
3. If the IPs are different:

• Create a new Security Group on AWS with the name of the first parameter.
• Revokes the old ip in this Security Group for ports 8080, 8081 and 9000.
• Allow access to ports 8080, 8081 and 9000 in the Security Group created for the actual external IP.
• Add the Security Group to the instance with the id received in the first parameter.
• Update the file old_ip with the actual external IP.