openssh bugs - Jan 2020 - [Bug 3110] New: Add a new ControlPath option: %a

https://bugzilla.mindrot.org/show_bug.cgi?id=3110

            Bug ID: 3110
           Summary: Add a new ControlPath option: %a
           Product: Portable OpenSSH
           Version: 8.1p1
          Hardware: amd64
                OS: Mac OS X
            Status: NEW
          Severity: enhancement
          Priority: P5
         Component: ssh
          Assignee: unassigned-bugs at mindrot.org
          Reporter: me at cweagans.net

A couple of web hosting providers that I work with have really long
usernames and hostnames like this:

codeserver.dev.1f1576dd-fa95-400c-a179-7ae962373aab at
codeserver.dev.1f1576dd-fa95-400c-a179-7ae962373aab.foo.bar:2222


If I have `ControlPath ~/.ssh/control/%r@%h:%p` in my ~/.ssh/config, I
get an error about the ControlPath being too long when I try to SSH
into one of those hosts. There's not a lot I can do about that as a
user and it's pretty frustrating to just have to disable connection
multiplexing.

I started thinking about this and I was wondering what it would take to
add a new token for the ControlPath option like %a. If you used this
token, you'd get a sha256 hash of the values of "%r@%h:%p". This
would
shorten up a ControlPath quite a bit at the cost of knowing which
socket is which.

Personally, I wouldn't care too much about that tradeoff, but I may
also not understand the security implications. I'd also be very open to
other alternatives here if there's another way.

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--- Comment #1 from Cameron Eagans <me at cweagans.net> ---
Oh, I forgot to mention: %a is for "auto" or "all". I
don't much care
about the specific letter used. This just made sense to me.

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Jakub Jelen <jjelen at redhat.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jjelen at redhat.com

--- Comment #2 from Jakub Jelen <jjelen at redhat.com> ---
See manual page for ssh_config. In the section TOKENS, there is already
the %C doing exactly that:

           %C    Hash of %l%h%p%r.

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Cameron Eagans <me at cweagans.net> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |WORKSFORME
             Status|NEW                         |RESOLVED

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Damien Miller <djm at mindrot.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |CLOSED

--- Comment #3 from Damien Miller <djm at mindrot.org> ---
closing resolved bugs as of 8.6p1 release

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