- stunnel-users - stunnel.org

Stunnel exits with timeout
by SP 19 Aug '16

19 Aug '16

Summary of problem (configuration and log details below): I am attempting to configure Stunnel to run a pop3s service on our server so that users can retrieve email securely. Stunnel is started as a systemctl service. If I include both the following in the stunnel.conf: accept = mail.myserver.net:995 connect = localhost:110 then systemctl will exit immediately with: Service [pop3s]: Each service must define two endpoints stunnel.service: Control process exited, code=exited status=1 Failed to start SSL tunnel for network daemons. If I comment the connect to 110 then it will start and hang then eventually timeout: stunnel.service: Failed with result 'timeout'. Below is my stunnel.conf and log excerpt from the start with the connect to 110 commented out. I would greatly appreciate any advice. ---stunnel.conf setuid = nobody setgid = nobody pid = /usr/local/var/lib/stunnel/var/run/stunnel.pid foreground = yes ;debug = info debug = 7 sslVersion = TLSv1.2 output = /usr/local/var/lib/stunnel/var/log/stunnel.log ;ciphers = HIGH:MEDIUM:+DH:!SSLv2:!aNULL:+SHA256:+SHA1:+MD5 ciphers = HIGH:+3DES:+DH:!aNULL:!SSLv2 transparent = yes delay = no fips = no compression = deflate client = no [pop3s] accept = mail.myserver.net:995 ;connect = localhost:110 cert = /etc/stunnel/stunnel.pem key = /etc/stunnel/stunnel.pem exec = /usr/local/sbin/gnu-pop3d execargs = --debug=000 --mdn --timeout=60 --ipv6 ----log excerpt ----- 2016.08.17 15:08:55 LOG7[ui]: Clients allowed=500 2016.08.17 15:08:55 LOG5[ui]: stunnel 5.35 on x86_64-unknown-linux-gnu platform 2016.08.17 15:08:55 LOG5[ui]: Compiled/running with OpenSSL 1.0.2h 3 May 2016 2016.08.17 15:08:55 LOG5[ui]: Threading:PTHREAD Sockets:POLL,IPv6 TLS:ENGINE,FIPS,OCSP,PSK,SNI 2016.08.17 15:08:55 LOG7[ui]: errno: (*__errno_location ()) 2016.08.17 15:08:55 LOG5[ui]: Reading configuration from file /etc/stunnel/stunnel.conf 2016.08.17 15:08:55 LOG5[ui]: UTF-8 byte order mark not detected 2016.08.17 15:08:55 LOG7[cron]: Cron thread initialized 2016.08.17 15:08:55 LOG5[ui]: FIPS mode disabled 2016.08.17 15:08:55 LOG6[ui]: Compression enabled: 1 method(s) 2016.08.17 15:08:55 LOG7[ui]: Snagged 64 random bytes from /dev/urandom 2016.08.17 15:08:55 LOG7[ui]: PRNG seeded successfully 2016.08.17 15:08:55 LOG6[ui]: Initializing service [pop3s] 2016.08.17 15:08:55 LOG6[ui]: Loading certificate from file: /etc/stunnel/stunnel.pem 2016.08.17 15:08:55 LOG6[ui]: Certificate loaded from file: /etc/stunnel/stunnel.pem 2016.08.17 15:08:55 LOG6[ui]: Loading private key from file: /etc/stunnel/stunnel.pem 2016.08.17 15:08:55 LOG6[ui]: Private key loaded from file: /etc/stunnel/stunnel.pem 2016.08.17 15:08:55 LOG7[ui]: Private key check succeeded 2016.08.17 15:08:55 LOG7[ui]: DH initialization 2016.08.17 15:08:55 LOG7[ui]: Could not load DH parameters from /etc/stunnel/stunnel.pem 2016.08.17 15:08:55 LOG6[ui]: Using dynamic DH parameters 2016.08.17 15:08:55 LOG7[ui]: ECDH initialization 2016.08.17 15:08:55 LOG7[ui]: ECDH initialized with curve prime256v1 2016.08.17 15:08:55 LOG7[ui]: SSL options: 0x03004004 (+0x03004000, -0x00000000) 2016.08.17 15:08:55 LOG5[ui]: Configuration successful 2016.08.17 15:08:55 LOG7[ui]: Listening file descriptor created (FD=7) 2016.08.17 15:08:55 LOG7[ui]: Option SO_REUSEADDR set on accept socket 2016.08.17 15:08:55 LOG7[ui]: Service [pop3s] (FD=7) bound to 60.62.114.105:995 2016.08.17 15:08:55 LOG6[cron]: Executing cron jobs 2016.08.17 15:08:55 LOG7[ui]: Created pid file /usr/local/var/lib/stunnel/var/run/stunnel.pid 2016.08.17 15:08:55 LOG5[cron]: Updating DH parameters 2016.08.17 15:10:01 LOG5[cron]: DH parameters updated 2016.08.17 15:10:01 LOG6[cron]: Cron jobs completed in 66 seconds 2016.08.17 15:10:01 LOG7[cron]: Waiting 86334 seconds 2016.08.17 15:10:25 LOG7[ui]: Found 1 ready file descriptor(s) 2016.08.17 15:10:25 LOG7[ui]: FD=4 events=0x2001 revents=0x1 2016.08.17 15:10:25 LOG7[ui]: FD=7 events=0x2001 revents=0x0 2016.08.17 15:10:25 LOG7[ui]: Dispatching signals from the signal pipe 2016.08.17 15:10:25 LOG7[ui]: Processing SIGNAL_TERMINATE 2016.08.17 15:10:25 LOG5[ui]: Terminated 2016.08.17 15:10:25 LOG7[ui]: Closing service [pop3s] 2016.08.17 15:10:25 LOG7[ui]: Service [pop3s] closed (FD=7) 2016.08.17 15:10:25 LOG7[ui]: Service [pop3s] closed 2016.08.17 15:10:25 LOG7[ui]: removing pid file /usr/local/var/lib/stunnel/var/run/stunnel.pid

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Logging Issues Causing Crash?
by Randall LeJeune 08 Aug '16

08 Aug '16

Hello all, Has anyone experienced a full log file causing stunnel issues in the past? We tried upgrading from 4.56 to 5.17 and the upgrade seemed to go fine at first, but a day or so later we began to have some disconnects. Later we downgraded to 5.01 which worked OK at first, but then we ran into the same kinds of problems again after a few days. We eventually put the stunnel.log file on a separate filesystem, but I am curious, has anyone else experienced any issues like this? Thanks, Randy

3 2

Config was working. Now it isn't after reboot
by Lee Savidge 02 Aug '16

02 Aug '16

I just reinstalled stunnel the latest version. When running I went through the creation of the pem file. I put in UK for the country code and the company name and put a . for everything else. It finished, I start the GUI and it works. I edited the config file to comment out the gmail IMAP section and reload it and it was fine. I rebooted, now it tells me tehre is an error in the config file. Why? I keep getting this problem. Rebooting seems to break the config somehow. Log shows this when stunnel starts: [ ] Cron thread initialized [ ] Running on Windows 6.1 [ ] No limit detected for the number of clients [.] stunnel 5.35 on x86-pc-msvc-1500 platform [.] Compiled/running with OpenSSL 1.0.2h-fips 3 May 2016 [.] Threading:WIN32 Sockets:SELECT,IPv6 TLS:ENGINE,FIPS,OCSP,PSK,SNI [ ] errno: (*_errno()) [ ] GUI message loop initialized [ ] Running on Windows 6.1 [.] Reading configuration from file stunnel.conf [.] UTF-8 byte order mark detected [.] FIPS mode disabled [ ] Compression disabled [ ] Snagged 64 random bytes from C:/.rnd [ ] Wrote 1024 new random bytes to C:/.rnd [ ] PRNG seeded successfully [ ] Initializing service [gmail-pop3] [ ] No certificate or private key specified [ ] SSL options: 0x03000004 (+0x03000000, -0x00000000) [ ] Initializing service [gmail-smtp] [ ] No certificate or private key specified [ ] SSL options: 0x03000004 (+0x03000000, -0x00000000) [.] Configuration successful [ ] Listening file descriptor created (FD=388) [ ] Option SO_EXCLUSIVEADDRUSE set on accept socket [ ] Service [gmail-pop3] (FD=388) bound to 127.0.0.1:110 [ ] Listening file descriptor created (FD=392) [ ] Option SO_EXCLUSIVEADDRUSE set on accept socket [!] bind: Permission denied (WSAEACCES) (10013) [!] Error binding service [gmail-smtp] to 127.0.0.1:25 [ ] Closing service [gmail-pop3] [ ] Service [gmail-pop3] closed (FD=388) [ ] Service [gmail-pop3] closed [ ] Closing service [gmail-smtp] [ ] Service [gmail-smtp] closed [!] Server is down [ ] Executing cron jobs [ ] Cron jobs completed in 0 seconds [ ] Waiting 86400 seconds The config file contains this: debug = debug output = stunnel.log [gmail-pop3] client = yes accept = 127.0.0.1:110 connect = pop.gmail.com:995 verifyChain = yes CAfile = ca-certs.pem checkHost = pop.gmail.com OCSPaia = yes [gmail-smtp] client = yes accept = 127.0.0.1:25 connect = smtp.gmail.com:465 verifyChain = yes CAfile = ca-certs.pem checkHost = smtp.gmail.com OCSPaia = yes I have pasted in only the stuff that isn't commented out. Why does this not work after a reboot? It makes no sense. -- =-----------------= Lee Savidge =-----------------= --

2 2

Installation problem on Windows 2003
by Tom Eberhard 01 Aug '16

01 Aug '16

Hello stunnel-users: I'm trying to install stunnel 5.35 on a Windows 2003 box, 32-bit. The installer runs to completion, but we get an error from SimpleFC: SimpleFC::AddApplication failed to add stunnel What is causing this error to come up, and what do I have to do to fix it? Googling just showed that SimpleFC is a plugin to interact with the Windows Firewall. Thanks, Tom This e-mail is intended solely for the person or entity to which it is addressed and may contain confidential and/or privileged information. Any review, dissemination, copying, printing or other use of this e-mail by persons or entities other than the addressee is prohibited. If you have received this e-mail in error, please contact the sender immediately and delete the material from any computer.

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Client-side SNI
by Vincent Deschenes 01 Aug '16

01 Aug '16

Hi, Anyone know if there is anything special to do to get ServerName sent when using stunnel in client mode to be able to connect to SNI enabled server? Using latest version of stunnel and openssl. Will stunnel use the name specified in the "connect=" config ? Thanks, Regards, Vincent Deschenes Ing. PMP Director of Operations Stelvio Inc. (+1) 514-281-8570

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stunnel only sends some emails, not all, and only on second attempt
by Martin Jaquess 28 Jul '16

28 Jul '16

Hi I'm using the latest Stunnel (5.35), running under Windows Server 2000, to download emails from Outlook(Office365)/Outlook 2016 to another email client called OfficeTalk which only supports unencrypted POP3, so it can't access Outlook directly. First problem is that although most emails are downloaded without problem, some stubbornly and consistently refuse to be downloaded. This omission doesn't seem related to attachments, encoding, size, date, or anything else that I can see. Has anyone else experienced this or have any idea why it might be happening?? Second problem is that the first download doesn't produce anything, but if I run the request again, it works - the only difference in the log files is the IP addresses I'd greatly appreciate any advice on this - I've checked the threads but can't find anything similar. Many thanks in advance Martin Config file for all attempts is:debug=7 output = c:\program files\stunnel\stunnel.log [outlook-pop3] client = yes accept = 127.0.0.1:110 connect = outlook.office365.com:995 Logfile for successful download of one email is:12:49:50 LOG7[cron]: Cronthread initialized12:49:50 LOG7[main]: Runningon Windows 5.012:49:50 LOG7[main]: No limitdetected for the number of clients12:49:50 LOG5[main]: stunnel5.35 on x86-pc-msvc-1500 platform12:49:50 LOG5[main]:Compiled/running with OpenSSL 1.0.2h-fips 3 May 201612:49:50 LOG5[main]:Threading:WIN32 Sockets:SELECT,IPv4 TLS:ENGINE,FIPS,OCSP,PSK,SNI12:49:50 LOG7[main]: errno:(*_errno())12:49:50 LOG7[ui]: GUImessage loop initialized12:49:50 LOG7[main]: Runningon Windows 5.012:49:50 LOG5[main]: Reading configurationfrom file stunnel.conf12:49:50 LOG5[main]: UTF-8byte order mark detected12:49:50 LOG5[main]: FIPSmode disabled12:49:50 LOG7[main]:Compression disabled12:49:50 LOG7[main]: Snagged64 random bytes from C:/.rnd12:49:50 LOG7[main]: Wrote1024 new random bytes to C:/.rnd12:49:50 LOG7[main]: PRNGseeded successfully12:49:50 LOG6[main]:Initializing service [outlook-pop3]12:49:50 LOG7[main]: Nocertificate or private key specified12:49:50 LOG4[main]: Service[outlook-pop3] needs authentication to prevent MITM attacks12:49:50 LOG7[main]: SSLoptions: 0x03000004 (+0x03000000, -0x00000000)12:49:50 LOG5[main]:Configuration successful12:49:50 LOG7[main]:Listening file descriptor created (FD=344)12:49:50 LOG7[main]: Service[outlook-pop3] (FD=344) bound to 127.0.0.1:11012:49:53 LOG7[main]: Found 1ready file descriptor(s)12:49:53 LOG7[main]: FD=204ifds=r-x ofds=---12:49:53 LOG7[main]: Service[outlook-pop3] accepted (FD=356) from 127.0.0.1:380112:49:53 LOG7[main]: Creatinga new thread12:49:53 LOG7[main]: Newthread created12:49:53 LOG7[0]: Service[outlook-pop3] started12:49:53 LOG7[0]: OptionTCP_NODELAY set on local socket12:49:53 LOG5[0]: Service[outlook-pop3] accepted connection from 127.0.0.1:380112:49:53 LOG6[0]: failover:round-robin, starting at entry #112:49:53 LOG6[0]: s_connect:connecting 132.245.224.162:99512:49:53 LOG7[0]: s_connect:s_poll_wait 132.245.224.162:995: waiting 10 seconds12:49:53 LOG5[0]: s_connect:connected 132.245.224.162:99512:49:53 LOG5[0]: Service[outlook-pop3] connected remote server from 192.168.15.102:380212:49:53 LOG7[0]: OptionTCP_NODELAY set on remote socket12:49:53 LOG7[0]: Remotedescriptor (FD=380) initialized12:49:53 LOG6[0]: SNI:sending servername: outlook.office365.com12:49:53 LOG6[0]: Peercertificate not required12:49:53 LOG7[0]: SSL state(connect): before/connect initialization12:49:53 LOG7[0]: SSL state(connect): SSLv2/v3 write client hello A12:49:53 LOG7[0]: SSL state(connect): SSLv3 read server hello A12:49:53 LOG6[0]: Certificateverification disabled12:49:53 LOG6[0]: Certificateverification disabled12:49:53 LOG7[0]: SSL state(connect): SSLv3 read server certificate A12:49:53 LOG7[0]: SSL state(connect): SSLv3 read server key exchange A12:49:53 LOG6[0]: Clientcertificate not requested12:49:53 LOG7[0]: SSL state(connect): SSLv3 read server done A12:49:53 LOG7[0]: SSL state(connect): SSLv3 write client key exchange A12:49:53 LOG7[0]: SSL state(connect): SSLv3 write change cipher spec A12:49:53 LOG7[0]: SSL state(connect): SSLv3 write finished A12:49:53 LOG7[0]: SSL state(connect): SSLv3 flush data12:49:53 LOG7[0]: SSL state(connect): SSLv3 read finished A12:49:53 LOG7[0]: 1 client connect(s) requested12:49:53 LOG7[0]: 1 client connect(s) succeeded12:49:53 LOG7[0]: 0 client renegotiation(s) requested12:49:53 LOG7[0]: 0 session reuse(s)12:49:53 LOG6[0]: SSLconnected: new session negotiated12:49:53 LOG7[0]: Peercertificate was cached (4882 bytes)12:49:53 LOG6[0]: NegotiatedTLSv1.2 ciphersuite ECDHE-RSA-AES256-SHA384 (256-bit encryption)12:49:53 LOG7[0]:Compression: null, expansion: null12:49:54 LOG6[0]: Read socketclosed (readsocket)12:49:54 LOG7[0]: Sendingclose_notify alert12:49:54 LOG7[0]: SSL alert(write): warning: close notify12:49:54 LOG6[0]:SSL_shutdown successfully sent close_notify alert12:49:54 LOG7[main]: Found 1ready file descriptor(s)12:49:54 LOG7[main]: FD=204ifds=r-x ofds=---12:49:54 LOG7[main]: Service[outlook-pop3] accepted (FD=404) from 127.0.0.1:380312:49:54 LOG7[main]: Creatinga new thread12:49:54 LOG7[main]: Newthread created12:49:54 LOG7[1]: Service[outlook-pop3] started12:49:54 LOG7[1]: OptionTCP_NODELAY set on local socket12:49:54 LOG5[1]: Service[outlook-pop3] accepted connection from 127.0.0.1:380312:49:54 LOG6[1]: failover:round-robin, starting at entry #212:49:54 LOG6[1]: s_connect:connecting 132.245.212.98:99512:49:54 LOG7[1]: s_connect:s_poll_wait 132.245.212.98:995: waiting 10 seconds12:49:54 LOG6[0]: SSL socketclosed (SSL_read)12:49:54 LOG7[0]: Sent socketwrite shutdown12:49:54 LOG5[0]: Connectionclosed: 67 byte(s) sent to SSL, 11900 byte(s) sent to socket12:49:54 LOG7[0]: Remotedescriptor (FD=380) closed12:49:54 LOG7[0]: Local descriptor(FD=356) closed12:49:54 LOG7[0]: Service[outlook-pop3] finished (1 left)12:49:54 LOG5[1]: s_connect:connected 132.245.212.98:99512:49:54 LOG5[1]: Service[outlook-pop3] connected remote server from 192.168.15.102:380412:49:54 LOG7[1]: OptionTCP_NODELAY set on remote socket12:49:54 LOG7[1]: Remotedescriptor (FD=428) initialized12:49:54 LOG6[1]: SNI:sending servername: outlook.office365.com12:49:54 LOG6[1]: Peercertificate not required12:49:54 LOG7[1]: SSL state(connect): before/connect initialization12:49:54 LOG7[1]: SSL state(connect): SSLv3 write client hello A12:49:54 LOG7[1]: SSL state(connect): SSLv3 read server hello A12:49:54 LOG6[1]: Certificateverification disabled12:49:54 LOG6[1]: Certificateverification disabled12:49:54 LOG7[1]: SSL state(connect): SSLv3 read server certificate A12:49:54 LOG7[1]: SSL state(connect): SSLv3 read server key exchange A12:49:54 LOG6[1]: Clientcertificate not requested12:49:54 LOG7[1]: SSL state(connect): SSLv3 read server done A12:49:54 LOG7[1]: SSL state(connect): SSLv3 write client key exchange A12:49:54 LOG7[1]: SSL state(connect): SSLv3 write change cipher spec A12:49:54 LOG7[1]: SSL state(connect): SSLv3 write finished A12:49:54 LOG7[1]: SSL state(connect): SSLv3 flush data12:49:54 LOG7[1]: SSL state(connect): SSLv3 read finished A12:49:54 LOG7[1]: 2 client connect(s) requested12:49:54 LOG7[1]: 2 client connect(s) succeeded12:49:54 LOG7[1]: 0 client renegotiation(s) requested12:49:54 LOG7[1]: 0 session reuse(s)12:49:54 LOG6[1]: SSLconnected: new session negotiated12:49:54 LOG7[1]:Deallocating application specific data for addr index12:49:54 LOG6[1]: NegotiatedTLSv1.2 ciphersuite ECDHE-RSA-AES256-SHA384 (256-bit encryption)12:49:54 LOG7[1]:Compression: null, expansion: null12:49:56 LOG6[1]: Read socketclosed (readsocket)12:49:56 LOG7[1]: Sendingclose_notify alert12:49:56 LOG7[1]: SSL alert(write): warning: close notify12:49:56 LOG6[1]:SSL_shutdown successfully sent close_notify alert12:49:56 LOG6[1]: SSL socketclosed (SSL_read)12:49:56 LOG7[1]: Sent socketwrite shutdown12:49:56 LOG5[1]: Connectionclosed: 67 byte(s) sent to SSL, 11884 byte(s) sent to socket12:49:56 LOG7[1]: Remotedescriptor (FD=428) closed12:49:56 LOG7[1]: Localdescriptor (FD=404) closed12:49:56 LOG7[1]: Service[outlook-pop3] finished (0 left)

1 0

HTTPS proxy tunnel. ssl handshake failure
by Kirill Franko 22 Jul '16

22 Jul '16

1 1

AiX 7.1 TL3 SP6 - Stunnel Memory Usages grows after 24 hours
by Benjamin, Earl 19 Jul '16

19 Jul '16

Hello Everyone, I am running Stunnel-5.29 in AiX 7.1 TL3 SP6. I have added the DH param to the bottom of my CERT file. After approximately 24 hours or so the Stunnel CPU usage jumps to about 50% and after a few days to about 90%. Is there a configuration setting I've missed or compile option I need to consider? Thanks for your assistance in advance. Below is a cleaned up version of my config file. -Earl ------------------------------------------------- ; Verify peer certificate verify = 2 ; Certificate/key is needed in server mode and in client mode cert = /Server-certificate-all.pem key = /Server-certificate-all.pem CAfile = /all_root_ca.pem ; Protocol version (all, SSLv2, SSLv3, TLSv1) sslVersion = TLSv1 ; PID path pid = /etc/oraserver_stunnel.pid ; Turn off Nagle algorithm socket = l:TCP_NODELAY=1 socket = r:TCP_NODELAY=1 ; Debug level debug = 2 ; Use it for client mode client = no ; Ciphers ciphers = DHE-RSA-AES256-SHA ; Service-level configuration [ oraserver_DB ] accept = 15210 connect = server:1622 [ oraserver_ASM ] accept = 15211 connect = server:1621 This message and any attachments are solely for the use of intended recipients. The information contained herein may include trade secrets, protected health or personal information, privileged or otherwise confidential information. Unauthorized review, forwarding, printing, copying, distributing, or using such information is strictly prohibited and may be unlawful. If you are not an intended recipient, you are hereby notified that you received this email in error, and that any review, dissemination, distribution or copying of this email and any attachment is strictly prohibited. If you have received this email in error, please contact the sender and delete the message and any attachment from your system. Thank you for your cooperation

1 0

Man in the middle attack possibility
by Abhinav Srivastava 19 Jul '16

19 Jul '16

Hi, I'm trying to use stunnel to provide encryption for my application to server communication. Server is already ssl aware. I configured my app to talk to localhost:xyz, and configured stunnel in client mode to relay traffic from localhost:<xyz> to actual service. The stunnel to service ssl protocol would use the server certificate, as server is already ssl aware. For any reason if stunnel is not running it would become possible for a non-elevated attacker/malware to spin up a tcp server listening to xyz, essentially taking advantage of my re-configuration of app to talk to localhost:xyz, and spoof the actual server. Even if my app to server protocol had some anti-spoofing mechanism say e.g., reverse CHAP, the malware can easily relay the challenge and response by using the actual service. In my case the actual app is iscsi initiator software that is not in my control and cant be modified, while the server is an iscsi tcp server which I am free to modify. Are there any guidance/best practices around preventing this attack with stunnel? Thanks Abhinav

1 0

Client certificates now required by default?
by Wiest, Damian 07 Jul '16

07 Jul '16

After building stunnel 5.34 from source I noticed that my old config (5.22) was not working. [dwiest@716161-compute2 ~]$ sudo ./stunnel /etc/stunnel/stunnel.conf 2016.07.07 14:07:41 LOG5[ui]: stunnel 5.34 on x86_64-unknown-linux-gnu platform 2016.07.07 14:07:41 LOG5[ui]: Compiled/running with OpenSSL 1.0.1e-fips 11 Feb 2013 2016.07.07 14:07:41 LOG5[ui]: Threading:PTHREAD Sockets:POLL,IPv6 TLS:ENGINE,FIPS,OCSP,PSK,SNI Auth:LIBWRAP 2016.07.07 14:07:41 LOG5[ui]: Reading configuration from file /etc/stunnel/stunnel.conf 2016.07.07 14:07:41 LOG5[ui]: UTF-8 byte order mark not detected 2016.07.07 14:07:41 LOG5[ui]: FIPS mode disabled 2016.07.07 14:07:41 LOG5[ui]: Configuration successful 2016.07.07 14:07:41 LOG5[cron]: Updating DH parameters 2016.07.07 14:07:42 LOG5[0]: Service [rabbitmq] accepted connection from 192.168.237.81:49535 2016.07.07 14:07:42 LOG3[0]: SSL_accept: Peer suddenly disconnected 2016.07.07 14:07:42 LOG5[0]: Connection reset: 0 byte(s) sent to SSL, 0 byte(s) sent to socket 2016.07.07 14:07:42 LOG5[1]: Service [rabbitmq] accepted connection from 192.168.237.81:49536 2016.07.07 14:07:42 LOG3[1]: SSL_accept: 140890C7: error:140890C7:SSL routines:SSL3_GET_CLIENT_CERTIFICATE:peer did not return a certificate But I haven't enabled client certificate verification! [dwiest@716161-compute2 ~]$ sudo grep verify /etc/stunnel/stunnel.conf ; verify = 2 I have to explicitly set verify to 0 or 1 in order to connect without a client cert. Is this intentional? The documentation suggests that by default no verification should be taking place. -Damian -- Confidentiality Notice: This e-mail transmission may contain confidential or legally privileged information that is intended only for the individual or entity named in the e-mail address. If you have received this communication in error, please notify me by return e-mail, and destroy this communication and all copies thereof, including any attachments. Apervita ® is a registered trademark of Apervita Inc.

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