特别感谢阿干同学的邮件分享。
详细方法
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代码如下:
Linux/mac下，在$HOME/.ssh/config中加入
Host *
ControlMaster auto
ControlPath <a>/tmp/ssh-%r@%h</a>
Host *
ControlMaster auto
ControlPath <a>/tmp/ssh-%r@%h</a>
至此只要第一次SSH登录输入密码，之后同个Hosts则免登。
配置文件分析
man ssh_config 5
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代码如下:
ControlPath
Specify the path to the control socket used for connection sharing as described in the ControlMaster section
above or the string “none” to disable connection sharing. In the path, ‘%l’ will be substituted by the
local host name, ‘%h’ will be substituted by the target host name, ‘%p’ the port, and ‘%r’ by the remote
login username. It is recommended that any ControlPath used for opportunistic connection sharing include at
least %h, %p, and %r. This ensures that shared connections are uniquely identified.
Specify the path to the control socket used for connection sharing as described in the ControlMaster section
above or the string “none” to disable connection sharing. In the path, ‘%l’ will be substituted by the
local host name, ‘%h’ will be substituted by the target host name, ‘%p’ the port, and ‘%r’ by the remote
login username. It is recommended that any ControlPath used for opportunistic connection sharing include at
least %h, %p, and %r. This ensures that shared connections are uniquely identified.
%r 为远程机器的登录名
%h 为远程机器名
原理分析
严格地讲，它并不是真正意义上的Session Copy，而只能说是共享Socket。
第一次登录的时候，将Socket以文件的形式保存到：/tmp/ssh-%r@%h这个路径
之后登录的时候，一旦发现是同个主机，则复用这个Socket
故，一旦主进程强制退出（Ctrl+C），则其他SSH则被迫退出。
可以通过ssh -v参数，看debug信息验证以上过程
备注
有同学说在linux上通过证书的形式，可以实现免登录，没错。
对于静态密码，完全可以这么干；对于动态密码（口令的方式），则上述手段可以方便很多。
