Question

Here is what I want to do :

1. SSH to server 1
2. inside server 1, SSH to server 2
3. inside server 2, SSH to server 3
4. inside server 3, run a single command ( like mysql )
5. inside mysql console, run another command.
6. then exit all the way to server 1

Is it possible to do a procedure like this ? If yes, then how ?

Answer 1

It is possible: Just execute ssh (or a corresponding Python program you upload first) on each new hop, and when you finally reach the target, execute mysql.

However, it’s not advisable: You should never enter passwords (or worse, store private keys) for one server on another server. That means that if server 1 is ever compromised, your whole network is compromised.

Instead, use the first two ssh sessions to create tunnels to the next hop, either with the -L option of the command-line ssh (which you probably need to use anyways, see above), or with paramiko.