SIGforum
What is stunnel?

This topic can be found at:
https://sigforum.com/eve/forums/a/tpc/f/320601935/m/9340088915

March 11, 2026, 04:58 PM
gjgalligan
What is stunnel?
I find some program called stunnel on one of my laptops.
I googled it but I don't really speak "software"gobbley goog.

Can anybody give a simple disciption of what it is and why I need it?


Integrity is doing the right thing, even when nobody is looking.
March 11, 2026, 05:28 PM
SigJacket
Secure tunnel app. Not quite a vpn, since it’s made for connecting at the app level.


That’s the simplest possible explanation I could come up with without diving into network things.


--
I always prefer reality when I can figure out what it is.

JALLEN 10/18/18
https://sigforum.com/eve/forum...610094844#7610094844
March 11, 2026, 05:36 PM
r0gue
If you're not using it already, I'd delete it.
March 11, 2026, 07:38 PM
Fenris
It's a German pastry, not entirely unlike strudel.




God Bless and Protect our Beloved President, Donald John Trump.
March 11, 2026, 08:03 PM
Pipe Smoker
quote:
Originally posted by Fenris:
It's a German pastry, not entirely unlike strudel.

Smile Smile Smile



Serious about crackers.
March 12, 2026, 11:23 AM
architect
Before commercial VPNs became a thing, system administrators would use tools like stunnel to protect network traffic between one site and another over a public network. This uses a technique called "encapsulation," usually with encryption of the payload. Theoretically, at least, any routeable network protocol can "carry" another network protocol. Many operating system's network stacks have support for this technique built in to them.

Back in the 90's, I used FreeBSD to encapsulate Novell Netware IPX/SPX inside TCP/IP so a customer's remote locations could access file servers, printers etc. located at their data center. Today, I use IPv6 in IPv4 tunneling to connect/route my IPv6-capable devices to the general Internet, and IPv4 in IPv4 so that remote LANS appear to be local to my home network.

Stunnel adds this functionality to OS's that don't already provide it e.g. Windows, Android, etc. Mostly, these days, people use more "user-friendly" software like commercial VPNs, OpenVPN, Wireguard, etc. for tunneling.