Porter flew to Houston after the Nationals completed a three-game series with the Mets.
The Astros have been looking for a permanent manager ever since they dismissed Brad Mills last month. Tony DeFrancesco is currently the interim manager.
It's not known how the interview went, but Porter is considered a highly-respected baseball man in the Nationals organization. In fact, some people in the organization believe that he will be Davey Johnson's successor after Johnson retires from baseball.
Besides being a third-base coach, Porter is an outfield coach and helps Johnson run the office.