title: EC2 won't accept RDS incoming data without ALL TCP 0.0.0.0/0
body: <p>This appears to be a case of the opposite of the common condition. My EC2 instance won't accept incoming RDS (MySQL) data without opening ALL TCP to 0.0.0.0/0.</p>
  
  <ol>
  <li><p>If in EC2 security group I allow ALL TCP 0.0.0.0/0, then the database works and site loads.</p></li>
  <li><p>If I remove ALL TCP 0.0.0.0/0 entry from EC2 security group, but still have Inbound 3306 (MySQL) open to 0.0.0.0/0, the site won't load due to database connection timeout. </p></li>
  </ol>
  
  <p>CentOS 6/MySQL
  Both in same region</p>