The following command describes connections for an endpoint specified by ARN::

  aws dms describe-connections --filters Name="endpoint-arn",Values="arn:aws:dms:us-east-1:123456789012:endpoint:ZW5UAN6P4E77EC7YWHK4RZZ3BE"

Output::

  {
    "Connections": [
      {
        "Status": "successful",
        "ReplicationInstanceIdentifier": "test",
        "EndpointArn": "arn:aws:dms:us-east-arn:aws:dms:us-east-1:123456789012:endpoint:ZW5UAN6P4E77EC7YWHK4RZZ3BE",
        "EndpointIdentifier": "testsrc1",
        "ReplicationInstanceArn": "arn:aws:dms:us-east-1:123456789012:rep:6UTDJGBOUS3VI3SUWA66XFJCJQ"
      }
    ]
  }