Actually, that may be it, thank you. I definitely overlooked this option when I browsed the man page. I'll pass on this information to some interested parties and give them a chance to make it work. And I'll probably try this myself at some point soon.

(Incidentally, it's an HTTP client that doesn't support HTTPS, even though the server does, so it appears I'll need protocol=connect and CAfile=... for certificate pinning as well.)

Best, Leon

On Wed, Jan 7, 2015 at 9:31 AM, Ludolf Holzheid <lholzheid@bihl-wiedemann.de

wrote:

On Wed, 2015-01-07 09:12:39 -0500, Leon Smith wrote:

...

Hi, this may be a slightly unusual request, but I was curious if

stunnel

...

could be used for securing clients that do not support TLS, to connect

to

...

services that optionally support TLS.

So, really, stunnel already does almost everything that would be

needed;

...

except that in this use case, it would be listening for incoming unencrypted connections, and then serve as a proxy to an encrypted connection to the actual service. While it might be nice to offer certificate-based authentication options in this scenario, it wouldn't

be

...

necessary for my intended use case, so stunnel wouldn't need access to

any

...

private certificates. However, certificate pinning would be pretty essential to what I have in mind.

Leon,

I'm not sure I understood your request, but isn't 'client = yes' what you are looking for?

Ludolf

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On Wed, Jan 7, 2015 at 11:01 AM, Ludolf Holzheid < lholzheid@bihl-wiedemann.de> wrote:

I don't know your setup, but if there is no proxy involved, you don't

need the 'protocol=...' option. For certificate pinning, you'll certainly need 'CAfile=...' or 'CApath=...', and 'verify=LEVEL' with LEVEL not below 2

Hmm, what do you mean by "no proxy involved?" Unless I'm modifying the source, wouldn't using stunnel essentially always be proxy?

To be even more explicit, the HTTP client is cabal-install, which is a program that downloads and compiles code from the Hackage public source code repository for Haskell. cabal-install is HTTP only, whereas Hackage supports both HTTP and HTTPS. I _could_ modify cabal-install, as it is free, libre, and open source software, but for reasons both good and bad, getting the changes pushed upstream is problematic. So I was curious about finding a quick workaround for those concerned about possible MITM attacks injecting malicious code into the packages, and came up with the idea of a stunnel or nginx proxy. (Some of the people who run Hackage are working on code signing, but who knows when that'll finally be available...)

Perhaps the man page would make a little bit more sense to me on this count if I had a better understanding of the TLS protocol and how it relates to https, but that's not something I honestly know all that much about. As it stands the man page is a bit opaque to me on this topic...

Best, Leon