[stunnel-users] Reverse DNS lookup in stunnel log possible?

mkanet at yahoo.com mkanet at yahoo.com
Fri Jul 26 23:47:18 CEST 2013

Thanks, I guess I could do the equivalent with a batch file; but, was really hoping for buitin support for this in stunnel.  It would be nice to see in the upcoming 5.00 release as an option.


Don't know on windows, but did a little test with a
script to get the hostnames. First did a test using you records, and then used
my current stunnel.log
script stlog.chk
grep -Eo '([0-9]{1,3}\.){3}[0-9]{1,3}'
/var/log/stunnel.log | sort | uniq 
echo "" >stout2
for a in `cat stout` ; do
  echo -n $a "
  host $a | awk
'{print $5}' >>stout2;
The results of stout2 are  localhost.  qe-in-f108.1e100.net.  qe-in-f109.1e100.net.  3(NXDOMAIN)  pa-in-f108.1e100.net.  pa-in-f109.1e100.net.
Probable would want to add some code to filter out
private address. 
Final step would be to scan original log and add the name
each of the lines with an ip. 
  Michael D. Setzer
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  Guam Community
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----- Forwarded Message -----
From: "mkanet at yahoo.com" <mkanet at yahoo.com>
To: "stunnel-users at stunnel.org" <stunnel-users at stunnel.org> 
Sent: Friday, July 26, 2013 11:16 AM
Subject: Fw: Reverse DNS lookup in stunnel log possible?

I haven't posted on this mail list in a while.  Is there anyone still out there?  I hope I'm sending to the correct mail-list.  Is there a better place I can ask my question below?

I'm pretty sure I can't be the first person who wanted to see reverse DNS name lookup in the stunnel log.  I tried looking in the settings and documentation; but, didn't see anything related to this.

----- Forwarded Message -----

I currently have stunnel strip SSL from incoming https connections; which then passes the connections to a proxy before ultimately reaching my web server.  So, the only easy way to see where incoming connections are coming from are in the stunnel log.

Below, is a small example of what my stunnel log looks like (no, those arent the real IPs ).  The information below would be much more useful to me if it included the DNS names in addition to their numeric IP.

I currently have the latest Windows version of stunnel installed.  It would be great to know how to get it to resolve DNS names as well in the log file; preferably without impeding general stunnel performance.  I tried several debug levels; but none them did reverse DNS lookup.  Hopefully someone know how to do this on a Windows stunnel setup.

2013.07.23 10:16:00 LOG5[10152:15136]: Service [stunnel-sslh] connected remote server from
2013.07.23 10:16:00 LOG3[10152:15136]: SSL_read: Connection reset by peer (WSAECONNRESET) (10054)
2013.07.23 10:16:00 LOG5[10152:15136]: Connection reset: 272 byte(s) sent to SSL, 96 byte(s) sent to socket
2013.07.23 10:17:53 LOG5[10152:4000]: Service [stunnel-sslh] accepted connection from
2013.07.23 10:17:53 LOG5[10152:4000]: connect_blocking: connected
2013.07.23 10:17:53 LOG5[10152:4000]: Service [stunnel-sslh] connected remote server from
2013.07.23 10:17:53 LOG5[10152:13212]: Service [stunnel-sslh] accepted connection from
2013.07.23 10:17:53 LOG5[10152:3348]: Service [stunnel-sslh] accepted connection from
2013.07.23 10:17:53 LOG5[10152:2884]: Service [stunnel-sslh] accepted connection from
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