The following command describes source endpoints in your account::

  aws dms describe-endpoints --filters Name="endpoint-type",Values="source"

Output::

  {
    "Endpoints": [{
      "Username": "dms",
      "Status": "active",
      "EndpointArn": "arn:aws:dms:us-east-1:123456789012:endpoint:SF2WOFLWYWKVEOHID2EKLP3SJI",
      "ServerName": "ec2-52-32-48-61.us-west-2.compute.amazonaws.com",
      "EndpointType": "SOURCE",
      "KmsKeyId": "arn:aws:kms:us-east-1:123456789012:key/94d5c4e7-4e4c-44be-b58a-c8da7adf57cd",
      "DatabaseName": "test",
      "EngineName": "mysql",
      "EndpointIdentifier": "pri100",
      "Port": 8193
    }, {
      "Username": "admin",
      "Status": "active",
      "EndpointArn": "arn:aws:dms:us-east-1:123456789012:endpoint:TJJZCIH3CJ24TJRU4VC32WEWFR",
      "ServerName": "test.example.com",
      "EndpointType": "SOURCE",
      "KmsKeyId": "arn:aws:kms:us-east-1:123456789012:key/2431021b-1cf2-a2d4-77b2-59a9e4bce323",
      "DatabaseName": "EMPL",
      "EngineName": "oracle",
      "EndpointIdentifier": "test",
      "Port": 1521
    }]
  }