Hi there,

Thanks for your feedback!

> Bear in mind, putting a password in an environment variable can be seen by 
> other users on the same system with "ps auxwwe".


Sure. But in my scenario, the control host is considered a „safe“ developer 
machine, while the target host is considered the „unsafe“ environment. I use 
this command on my laptop to deploy to lots of cloud machines – there’s noone 
other than me on my laptop (hopefully ;-)), but instead, I’d like to keep the 
target machine configurations as secure as possible (no passwordless sudo, no 
root login).

> The environment variables of a process when it was started are available via 
> /proc/<pid>/environ file. So while other users on that system can't see the 
> environ, every other process running as your target user could.
>
> Worse, however, your "echo" process puts the password in arguments, and any 
> local user can see program name and args for all running processes. That's a 
> no-no.

Hm, I’m not sure I understand the implications. The whole password handling 
happens on the machine where I execute rsync (it’s done in "--rsh" not in 
"--rsync-path“) – which in my scenario is a developer’s laptop. So it’s not the 
target users that can see the environment but only my own account on my own 
developer machine.

Plus, I don’t understand what you mean with „putting the password in 
arguments“. The environment variable expansion happens on my control machine 
exactly at the time when rsync tries to establish a connection to the target 
machine by running the shell code from --rsh inside a shell. This will create a 
subshell for echo and cat where the environment variable is read and written to 
stdout. stdout is then piped through ssh to the remote machine where "sudo -S" 
reads it on its stdin. It is never in any argument list.

Please correct me if I’m wrong here.

Best,
Mark

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