Tom,

On 11/4/19 17:16, Tom (AST) Watson wrote:

Yes, I understand about ALPN. Sorry I described in detail. Unfortunately application #2 wants encrypted http2 (it is a go program). Application #1 wants to talk in http2 (I can't change that!) and it doesn't encrypt "naturally" (and I want to see what is going on [Wireshark] as well) In looking further I might be able to get application #2 to go plaintext (I found a pointer). Yes, it seems that stunnel doesn't support ALPN, wishful thinking on my part

Back to the salt mines. (*SIGH*)

How difficult would it be to enable HTTP/1.1 on that application #1? I've never seen an h2-only service before. h2 is more effective for web applications that make a lot of tiny requests (like small resources for pages, scripts, etc.). Most API-based services don't really get any benefit from using h2.

-chris

-----Original Message----- From: stunnel-users stunnel-users-bounces@stunnel.org On Behalf Of Christopher Schultz Sent: Monday, November 4, 2019 13:59 To: stunnel-users@stunnel.org Subject: [External] Re: [stunnel-users] Extensions when negotiating TLS

Tom,

On 11/4/19 16:05, Tom (AST) Watson wrote:

...

Well, I thought it would be "easy", but maybe not. I have an application (#1) that uses http2, and isn't encrypted. No problem here. Now I have another application (#2) that insists on using https to talk to application #1. So I gleefully setup stunnel to connect the two. Well, application #2 starts talking to stunnel with a "Client Hello" packet, and it includes an extension "Application Layer Protocol Extension" of "h2".

This is called ALPN, and is a requirement for h2s.

...

While not versed in the minutia, I take this that the client (application #2) wants to talk "http2" to the server (application #1).

Yep, pretty much.

...

OK, that is what I want. The problem is that stunnel doesn't respond with ANY "Application Layer Protocol Extension" indicating acceptance of this request in its "server hello". This means that application #2 fails in its negotiation. No joy!

Now I know that application #1 will nicely talk http2, but how do I get stunnel to communicate this to application #2 (as encrypted http2). Am I missing something in my (pretty simple) configuration file?

I can't find any references to stunnel supporting ALPN. You may be (temporarily) out of luck, at least with stunnel.

You mentioned that app #2 insists on encryption (great, usually). Is there a requirement that it use h2? Or can it be configured to use HTTP/1.1?

-chris