[stunnel-users] stunnel-users Digest, Vol 179, Issue 5

Brent Kimberley brent_kimberley at rogers.com
Sat Jun 15 21:48:26 CEST 2019

>> Is there something missing ?

Can you please elaborate?  https://www.stunnel.org/auth.html

Subject: Using STunnel4 with both SSL/TLS proxy AND PSK authentication

Hi, all.

We've got a specific use case where we need to implement an stunnel4
'tunnel' in the following format:

Client <---> client-side stunnel4 <---> server-side stunnel4 <---> server

The specific case for this is because of a server that does NOT support
SSL on the remote side nor client side, and we need to use two stunnel4
instances to establish the "secure" tunnel.

We can get it working with straight SSL/TLS certificates for a secure
connection between the two but can't seem to add authentication to this,
we want to get the stunnel4 on the client side and the stunnel4 on the
server side to have to have some kind of authentication/exchange between

Whenever we add the PSK options or client certs to the thing, we
immediately get SSL/TLS problems, as it doesn't seem to support SSL/TLS
handshakes properly at that point.

Is there something I'm missing within the STunnel4 documentation about
establishing the SSL/TLS tunnel AND adding an authentication component,
or is this not possible?? It doesn't currently seem possible based on my


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