[stunnel-users] older browsers, stunnel and privoxy

Thu Dec 20 16:45:52 CET 2018

On Thu, 20 Dec 2018 14:18:10 +0100
kovacs janos <kovacsjanosfasz at gmail.com> wrote:

> thank you for the explanation, but if a proxy cant read the traffic
> encrypted by stunnel, that means even if the set of possible hostnames
> are given, the destination server could not read the request unless
> there is another stunnel in front of the server which can receive and
> decrypt the request. which i obviously dont have access to
> 

Hi,

O_o

Really, where did you understand that???!!!

Stunnel is a program to give encryption capabilities to programs
that can't establish secure connections. That doesn't mean that at
both ends there should be a Stunnel instance running!!!!!

As long as both ends have the same ciphers, that is what the
handshake is for, to negotiate the security of connection, it doesn't
matter what program handles the secure connection at the end point.

And, again, the proxy can't handle the connection because it doesn't
receive what expects: an HTTP header to tell where to redirect the
data. And that isn't provided by Stunnel.

Let's see if with a "sketch" you understand it.

1. As client mode, Stunnel listen to 127.0.0.1 port 1256 and connects
to somehots:565 (totally invented destination host and port to avoid
you any further confusion)

2. Program sends text-plain to 127.0.0.1:1256

3. Stunnel takes it and connects to destination

4. After a handshake with secure connection parameters, encrypts that
data and sends to destination

5. Any dialog between destination and Stunnel would be encrypted
after this.

6. Responses from destination would be decrypted and send them back
in text plain to the program that requested Stunnel to connect.

7. Repeat, except handshake, until there is no need of the connection
by the initiating program.

It doesn't do anything else. And it is almost the opposite when
running as server.

Did you understand it?

The proxy server is expecting an HTTP header and Stunnel doesn't
provide it. End of story.

Regards.