[stunnel-users] stunnel 4.33 stops (crashes?) after undetermined running time

Markus Borst M.Borst at hrz.tu-darmstadt.de
Wed May 26 15:47:23 CEST 2010


I have a strange problem with current stunnel (4.33): It just crashes 
after some time. The time is variable, I suspect it stops after a number 
of connections.

- Windows Server 2003 SP2 (also happens on Windows Server 2008R2)
- stunnel runs as service
- stunnel is configured to run as ssl server for imap and pop3 with our 
certificate (including key-chain)

stunnel was running fine for years on the Windows Server 2003. After 
upgrade to stunnel 4.33, the stunnel service process first worked fine, 
the just stopped working after some time:
- The windows service "stunnel" was stopped
- the stunnel.log (standard debug level) showed not error or other entry 
at the time of the stop.
- The windows eventlog shows:
Event 7034, Service Control Manager
The stunnel service terminated unexpectedly.  It has done this 1 time(s).
(I'm not 100% sure, whether this event log message corresponds to the 
stunnel crash I described or to another crash.)

I have downgrade to version 4.32, the stunnel service now runs 
uninterrupted as before.

Since the time of crash varies somewhat, seemingly with the current load 
of the server, I suspect that stunnel crashes after a certain amount of 
ssl connections, but I'm not sure. This has happened on two different 
servers (Windows Server 2003 SP2 and Windows Server 2008 R2).

Is this a known problem?

I'd love to do some further tests, but since this is a production 
system, I cannot test it in our normal environment. A program to 
generate random ssl connections would come handy to further analyze the 

Markus Borst

TU Darmstadt
Hochschulrechenzentrum (HRZ)
Markus Borst
Adresse: 	Petersentrasse 30, 64287 Darmstadt, Germany
Tel.: 	06151/16-2056
Email: 	M.Borst at hrz.tu-darmstadt.de

More information about the stunnel-users mailing list