[stunnel-users] Connecting stunnels

Ludolf Holzheid lholzheid at bihl-wiedemann.de
Thu Mar 31 10:19:23 CEST 2016


On Thu, 2016-03-31 06:16:24 +0000, Juhasz Gabor wrote:
> Hi Ludolf,
> 
> Thanks for you reply.
> 
> Sorry, my first explanation was a bit fuzzy.
> 
> I modofied your picture a bit to explain what I want :
> 
>    stunnel client          stunnel server          stunnel client
>  +---------------+       +------------------+    +---------------+
>  |               |       |                  |    |               |
>  | telnet client |       |    5.6.7.8:993 <======== 4.5.6.7:y    |
>  | 127.0.0.1:x   |       |      stunnel     |    |    stunnel    |
>  |  :            |       |    127.0.0.1:q   |    |  127.0.0.1:p  |
>  |  :            |       |         :        |    |       :       |
>  |  V            |       |         :        |    |       :       |
>  | 127.0.0.1:23  |       |    127.0.0.1:z   |    |       V       |
>  | stunnel       |       |        stunnel   |    | 127.0.0.1:23  |
>  | 1.2.3.4:y ===============> 5.6.7.8:992   |    |  telnetserver |
>  |               |       |                  |    |               | 
>  +---------------+       +------------------+    +---------------+ 

Hi Gabor,

in your picture above, I don't understand who is supposed to establish
the connection (i.e. who is to act as a client) and who is supposed
to wait for connections (i.e. who is to act as a server).

An IP connection is similar to a telephone connection.  The caller
(acting as the client) is supposed to dial the number of the callee's
phone and the callee (acting as the server) is supposed to sit next to
this very phone, waiting for incoming connections.

In my picture, I tried to depict this by giving the connections 'a
direction':  The unit at the arrow head is the server, the unit at the
arrow tail is the client.


/Maybe/ you are thinking of running the stunnel instance in server
mode on a different host than the telnet server:

 telnet client's host      intermediate host     telnet server's host
  +---------------+       +------------------+    +----------------+
  |               |       |                  |    |                |
  | telnet client |       |                  |    |                |
  | 127.0.0.1:x   |       |                  |    |                |
  |  :            |       |                  |    |                |
  |  :            |       |                  |    |                |
  |  V            |       |                  |    |                |
  | 127.0.0.1:23  |       |    5.6.7.8:z ............> 4.5.6.7:23  |
  | stunnel       |       |    stunnel       |    |    telnet      |
  | 1.2.3.4:y ===============> 5.6.7.8:992   |    |    server      |
  |               |       |                  |    |                | 
  +---------------+       +------------------+    +----------------+ 

This is essentially the same as my first picture except for the
'connect' statement in the configuration file of the stunnel in server
mode.

Ludolf

-- 

Ludolf Holzheid
 
Bihl+Wiedemann GmbH
Floßwörthstraße 41
68199 Mannheim, Germany
 
Tel: +49 621 33996-0
Fax: +49 621 3392239
 
mailto:lholzheid at bihl-wiedemann.de
http://www.bihl-wiedemann.de
 
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Geschäftsführer: Jochen Bihl, Bernhard Wiedemann
Amtsgericht Mannheim, HRB 5796


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