= 2020-10-14 =

== SSH ==

* 工作上需要經過兩層跳板機才能存取到 AWS EMR，先前使用 `.ssh\config` 裡面的 `ProxyCommand`，但跳板機的設定比較嚴，研究了一下解法，除了靠 `ssh -J userA@跳板機A,userB@跳板機B userC@目的機` 以外，也可以使用 `.ssh\config` 裡的 `ProxyJump`
* manpage 說明: `man ssh_config`
{{{
#!bash
ProxyJump
             Specifies one or more jump proxies as either [user@]host[:port] or an ssh URI.  Multiple proxies may be
             separated by comma characters and will be visited sequentially.  Setting this option will cause ssh(1)
             to connect to the target host by first making a ssh(1) connection to the specified ProxyJump host and
             then establishing a TCP forwarding to the ultimate target from there.

             Note that this option will compete with the ProxyCommand option - whichever is specified first will pre-
             vent later instances of the other from taking effect.

             Note also that the configuration for the destination host (either supplied via the command-line or the
             configuration file) is not generally applied to jump hosts.  ~/.ssh/config should be used if specific
             configuration is required for jump hosts.
}}}