mac connect to host localhost port 22: Connection refused

在Mac OS X 10.10.5学习hadoop的过程中，输入命令ssh localhost得到
ssh: connect to host localhost port 22: Connection refused
解决方法是选择系统偏好设置->选择共享->点击远程登录
然后再输入命令ssh localhost发现已经解决问题

找到解决方案来自于
http://stackoverflow.com/questions/6313929/how-do-i-open-port-22-in-os-x-10-6-7