Usage

usage: update_aws_sg.py [-c <config file>] \
             -s <security group> [-f] \
                [-n <ip address>] \
             [-p <profile name>]

-c <config_file>        Run using the config file, if provided.  If the
                        config file is empty or does not exist, the
                        config will run and save values in the specified
                        file.  The script will run without arguments when
                        the config file is found at:
                                /home/mike/.config/.aws_sg_ddns.conf

-s <security group>     Security Group to update.  Required argument if
                        config file is not provided.  If config file and
                        this argument are provided, this argument will
                        SUPERCEDE the config file.

-f                      Force IP address update, even if the record is
                        the same as the current IP address.

-n <ip address> Use the specified IP address instead of the IP
                        address that this script is running on.  CIDR
                        notation /32 is added automatically.

-p <profile name>       Run the AWS CLI as the named profile, similiar to
                        running aws --profile <profile name>


AWS CLI must already be configured with the appropriate credentials.  At
minimum, the AWS CLI must have the following rights:

* ec2:DescribeSecurityGroups
* ec2:AuthorizeSecurityGroupIngress
* ec2:RevokeSecurityGroupIngress

The last two rights (AuthorizeSecurityGroupIngress, RevokeSecurityGroupIngress)
can be restricted to the specific security group that holds your Dynamic IP.