Feature: ControlPath connection uniqueness with JumpHost

[Alexandre Guédon]

Hi,

Using Ansible, which takes advantage of ssh's ProxyCommand, I realized I
couldn't make the ControlPath unique in every situation:

If two hosts share the host-port-user in 2 different subnets, you end up
with the same socket name, and there is no %(?) option to differentiate
them.
For example, user at 10.0.0.2:22 via both machineA & machineB are different,
but used sequentially quickly, there is no way for me to make the
ControlPath argument unique while still reusing the connection for speed.

So this is more of a feature / idea:
Could an argument like %C (hash) be introduced, but one that would hash
other options outside of %l%h%p%r, so that connection changing options like
ProxyCommand are taken into account and make the socket name unique?

That way ssh would have a way to create sockets that are unique per
connection, including ProxyCommand, ProxyJump, etc, thus preventing wrong
socket reuse.

Cheers!
Alex