Cannot Connect MySQL Workbench to RDS

Question

I had a connection that previously worked fine that I have not used in some time.   My internet service provider uses Dynamic IP's, so I have to continually update Inbound Routes.   I now cannot get connected using any method including Boto3 or MySQL Workbench.  I have added my current IP to the Inbound Routes as well as the CIDR range of XX.XX.00.00/32.   I have also tried to allow all traffic from all IP addresses.   I have set up Security Groups, tied them to my RDS VPC and made my database publicly available on all IPs.   My database is up and Available.   I suspect there is a problem with either the VPC being properly connected to subnet routes or Internet Gateway, but I will never figure that out with the AWS documentation.  I have spent an entire day on this.   On a related topic, the system has created a number of Security Groups for Sagemaker, Amplify, EC2 and other services I have tried. I am concerned that perhaps some of these are causing conflicts - I cannot delete even though I have not used the service and deleted the applications.

Answer

Hello.

Is RDS launched in a public subnet and has public access enabled?  
If public access is enabled, you can check the global IP address by resolving the name of the RDS endpoint.  
https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_VPC.WorkingWithRDSInstanceinaVPC.html#USER_VPC.Hiding

As an aside, it is not good security to place RDS directly in a public subnet.  
Therefore, we recommend accessing using Session Manager's port forwarding function, etc., as shown in the document below.  
https://aws.amazon.com/jp/blogs/mt/use-port-forwarding-in-aws-systems-manager-session-manager-to-connect-to-remote-hosts/

Answer

To answer your last point first, new security groups won't interfere like you suggest, i.e. they won't close a port that was previously open (it's the other way round - the only change they can make is to open a port that was previously closed).

@Riku's point about not having the RDS database in a publiuc subnet is very good advice. The RDS instance wil be running in a subnet group, and if it needs to be accessible from the internet then every subnet that makes up that subnet group must have a route to the internet gateway in its routing table https://docs.aws.amazon.com/vpc/latest/userguide/route-table-options.html#route-tables-internet-gateway

It may be useful here to use Reachability Analyser https://docs.aws.amazon.com/vpc/latest/reachability/getting-started.html

Be aware that this isn't free, it's about 10c per use -see the Network Analysis tab of https://aws.amazon.com/vpc/pricing/

Cannot Connect MySQL Workbench to RDS

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