#32 ControlMaster / ProxyJump

[bitozoid]

Let's say I have four hosts:

• M: my local machine,
• P: a proxy machine (logged in via PubkeyAuthentication),
• D: a remote machine that I have direct access to,
• H: a remote machine that I do not have direct access to, but I can reach through P (somehow hidden).

If I ssh from M to D using 'ControlMaster auto', once I close the shell connection the mux connection is kept open for future connections. That is, two processes are running in M:

• an ssh interactive process, and
• another independent ssh master process named '[mux]'

but the former is killed once I close the shell, and the latter is the one kept open for future connections.

If I sshpass from M to D using 'ControlMaster auto', I get three processes:

• an sshpass process, parent of
• an ssh interactive process, child of the sshpass process,
• an independent ssh master process named '[mux]',

and only the mux process survives after the shell is closed, so it can be reused.

If I ssh from M to H using 'ControlMaster auto' and P as the ProxyJump host, then I get four processes:

• an ssh interactive process to H, parent of
• an ssh interactive process to P,
• an independent ssh master process name '[mux]' to P
• an independent ssh master process name '[mux]' to H

and again, the first one is killed once I close the shell but the other three are kept running. So that, I can reuse the socket for later usage.

However, if I sshpass from M to H using 'ControlMaster auto' and P as the ProxyJump host, then I also get five processes:

• an sshpass process, parent of
• an ssh interactive process to H, parent of
• an ssh interactive process to P, grandchild of the sshpass process,
• a ssh master process name '[mux]' to P
• a ssh master process name '[mux]' to H

BUT then when I close the remote shell, everyone dies but the mux process to P, and the socket that connects to H disappear. So that, I cannot reuse the previous connection.

This looks like an sshpass bug to me, since ssh seems to work fine when used without sshpass.

A simplified config in this case would be:

Host H
  PubkeyAuthentication no
  Proxyjump P
Host D
  PubkeyAuthentication no
Match host !localhost,*
  ControlMaster auto
  ControlPath ~/.ssh/sockets/test-%h
  ControlPersist 30m