Re: [Discussion] Have curl honor OpenSSH configurations

From: Timothe Litt <litt_at_acm.org>
Date: Thu, 11 Aug 2022 12:38:13 -0400

On 11-Aug-22 10:23, Randall via curl-library wrote:
> Washttps://github.com/curl/curl/issues/9285
>
> Originally opened by Ben Voris. The request was to have curl support OpenSSH
> config specifications. I am opening a discussion on this subject from the
> above case. The ask is whether it would make sense to have an option to
> allow curl to honor ~/.ssh/config while attempting to connect?
>
> Ben Voris has a significant usability point in the case, including: " I had
> hoped that because curl libssh and libssh uses OpenSSH, it would honor the
> config file and so allow curl to behave like OpenSSH clients."
>
> Many software projects other than OpenSSH honor ~/.ssh/config. An option in
> curl like --use-ssh-config might be something of value even if not the
> default.
>
> Regards,
> Randall
>
> --
> Brief whoami: NonStop&UNIX developer since approximately
> UNIX(421664400)
> NonStop(211288444200000000)
> -- In real life, I talk too much.
>
>
>
This seems like the wrong way to approach the original request (stated
on github)  for several reasons.

Reading other commands' config files creates unmanaged dependencies on
those projects - formats, options, and/or defaults may or may not be
stable.  Which commands deserve this treatment is also unbounded -
should curl read ~/.ftp?  .mx? .freepopsd? .firefox? .gopher? .tftp?
.telnet?  ...  Besides reading the config files in ~, what about
/etc/sysconfig (or /etc/default)? And the commands that scan a .d
directory for additional config files?  Really, this gets out of hand
really, really fast.

It seems more reasonable to have a --default-port option, then put it in
~/.curlrc or use --config.  E.g.

curl --config $(HOST).curl.ssh.cfg

where example.net.curl.ssh.cfg might contain

default-port 65534

(and any other useful options - perhaps proxy to use, --compressed-ssh,
etc).

Or simply (with no change required to curl)

url = "sftp://someuser_at_example.net/file.ext"

Or have the makefile extract the port number from your HOST variable
when generating the ssh command.  Or have the makefile generate a
suitable --config as a temporary file.

Or (more generally useful) extend the curl config file syntax to have
per-host options, e.g. perhaps

[altport.example.net]

default-port 65534

[otherport.example.net]

default-port 43556

[*.example.net]

compressed-ssh

There are other reasonable solutions, but reading other commands config
files isn't one of them.

Timothe Litt
ACM Distinguished Engineer
--------------------------
This communication may not represent the ACM or my employer's views,
if any, on the matters discussed.

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Received on 2022-08-11