[stunnel-users] stunnel used as jump host for SFTP

Tue Jun 19 20:12:38 CEST 2018

Hello,

I am trying to test stunnel to see if it can provide the functionality we need. We are a Windows shop.
What we need is for multiple client machines (I call these C1, C2, C3) to connect to our server (S).
Server S will connect to a remote SFTP server (port 22). I call the remote SFTP server "R".
C1, C2, C3 and S are all inside our firewall.
Currently S can connect and send files to R using SFTP (port 22).
The problem is that R does not accept a range of IP addresses, and has a limit on the number of IP addresses they can accept.

So, what I need is for C1, C2, C3 to be able to connect to server R using S as a jump host.
>From R's perspective, it should be like the connection is coming from S.

Question 1: can stunnel be used to accomplish this?

Question 2: I have installed stunnel in a test server ("stunnel -install" actually from the bin folder), and configured the conf like this:

[sftp]
accept=127.0.0.1:22
connect=some.remote.server.com:22

I tried to use Winscp SFTP client to test a connection, but it times out.
I then checked S, and I don't see anything listening on port 22. I did "netstat -a" and I don't see anything listening on port 22.

Was something wrong in the "stunnel -install" command? Shouldn't it be listening on port 22?
Also, I uncommented the entry for log, but I don't see any log file in the stunnel folder/subfolders

; Debugging stuff (may be useful for troubleshooting)
debug = info
output = stunnel.log

Thanks for your help,
Cecilia

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