Mac OSX上的Oracle连接问题：“状态：失败 - 测试失败：Io异常：网络适配器无法建立连接”

I'm trying this with Oracle SQL Developer and am on an Intel MacBook Pro. But I believe this same error happens with other clients. I can ping the server hosting the database fine so it appears not to be an actual network problem.I'm trying this with Oracle SQL Developer and a