~/.ssh/config file, I have been using a socket file for every host that I connect to, so TCP sessions can be re-used for faster connecting to a host I already am connected to. I had several iterations of the exact filename for this, as with longer hostnames, the filename becomes too long.
ControlPath ~/.ssh/sockets/%r@%h-%p and
ControlPath ~/.ssh/sockets/%r@%h I still ran into problems. Luckily, I came across this helpful gist which mentioned the
%C formatting option to generate a hash of
%l%h%p%r instead of printing the whole hostname including fully qualified domain name and such. The following snippet works wonders:
Host * ControlPath ~/.ssh/control/%C ControlMaster auto