November 2018 - stunnel-users

stunnel FIPS mode 140-2/ Other Modes
by mehmet ozisik 19 Sep '25

19 Sep '25

Hi All, I would like to ask a question about stunnel fips mode. There are lots of question and answers on the internet related with this, but I could not find any answer related with mine. I am compiling with openssl (auto detecting fips) . Here is a part of confgiure output : checking for FIPS_mode_set... yes configure: FIPS mode detected So I am thinking that fips also is being included. Then I try to run stunnel on target platform (in stunnel.conf fips=yes) and it gives below error : Compiled/running with OpenSSL 0.9.8w-fips 23 Apr 2012 Threading:PTHREAD Sockets:POLL,IPv6 SSL:ENGINE,OCSP,FIPS Reading configuration from file stunnel.conf FIPS_mode_set: 2D06906E: error:2D06906E:FIPS routines:FIPS_CHECK_INCORE_FINGERPRINT:fingerprint does not match there are lots of information about this errror on internet. Then when I configure stunnel.conf with fips=no, stunnel is running successfully. I know that fips=yes means that enables FIPS 140-2 mode and I guess my fips canister does not supoort fips 140-2 mode (I do not know which fips mode it has supported). Now my question is coming : When I set fips=no, stunnel also starts with other available fips modes which the canister included? Or it skips running fips mode completely? Plase inform me if anyone has any idea? Regards

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Requests to cloud server that requires host header
by Lorne Kates 13 Nov '24

13 Nov '24

(related to Akamai message from before-- but I have better troubleshooting information). I'm tying to route traffic through stunnel to a "cloud" based-endpoint. That endpoint has a static server name-- test.authorize.net. (This is the dev sandbox for auth.net) But if you do an nslookup on test.authorize.net, you'll get back a different servername and IP, because it's so wonderfully "cloud". Stunnel apparently tries to connect to the nslookup value. The server rejects the request because it can't route it back to test.authorize.net. I've tried adding "delay = yes" and "sni = test.authorize.net", but neither work. To see this in action, a simple setup with any accept, then connect to test.authorize.net:443 in client = yes mode. This is what a valid response looks like (13 -- give me the darn merchant ID in a POST): https://test.authorize.net/gateway/transact.dll This is what you'll get if you try to use stunnel (400 invalid url) : https://23.195.204.150/gateway/transact.dll So how can I get stunnel to send the proper Request Header (host: test.authorize.net) make sure it's using http/1.1, etc?

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Re: [stunnel-users] CPU 100%
by Eric Eberhard 06 Nov '24

06 Nov '24

Long ago I had a server with a bad network card. Every once in a while it would spew uncontrollable bytes onto the network. If you open a stunnel connection and it does that this could very well be the problem. If it cheap, try changing the network card. If not, you should be able to look in your firewall/router and it will tell you who is sending what bytes to whomever. See if that machine is indeed streaming the bytes in massive quantities. If not, I would suspect your stunnel is getting stuck in it's own loop. There are a million reasons this can happen (well a few less than a million) - such as maybe a bad library in the FreeBSD or a bad choice in the Makefile - such as doing threads or something in a way your O/S does not like (I use threads=fork or whatever it is, instead of actual threading). You might tinker with some of the options that make the stunnel build and try different ones. Especially if stunnel was compiled on a different version of the O/S - could be differences in bytes in things and who knows what. That is all I can suggest beyond setting the debug level to 7 (I think is highest) and then watching the log file. Eric From: stunnel-users [mailto:stunnel-users-bounces@stunnel.org] On Behalf Of Murrey, Brian J. Sent: Wednesday, October 17, 2018 10:57 AM To: stunnel-users(a)stunnel.org Subject: [stunnel-users] CPU 100% We are running stunnel 5.49 on FreeBSD 11.2 and we're running into a problem once in a while. CPU pegs at 100% when we get an stunnel connection from one of our external devices. This affects 100% of all cores and we can't even log in to console. To mitigate this temporarily, we have a script running in the background to watch when stunnel begins to spike and restarts the daemon. It doesn't happen 100% of the time, and so far I have been unable to distinguish what makes the connection do this to the CPU. Have any of you run in to this issue? Sincerely, Brian Murrey System Engineer II, IT Infrastructure _____ NOTICE: This message may contain privileged and confidential information and/or protected health information intended solely for the use of the named recipient and may be privileged or otherwise protected by law. If you are not the intended recipient of this message, you should immediately notify the sender and delete this message. Do not disseminate, reproduce, or review this message or attachments if you are not the intended recipient. The sender or others may have legal rights restricting the dissemination of the information contained in this message and, as a result, remedies against you in the event of the improper dissemination of confidential information, trade secrets, personal information or privileged communications. This message is the work of the sender and does not necessarily reflect the position, views, or policies of TriMedx LLC or its affiliates. WARNING: The integrity and security of this message cannot be guaranteed and may contain or transmit a virus or other illicit code. Neither TriMedx LLC or its affiliates accept liability for any damage attributable to viruses or illicit code transmitted through this message or an attachment.

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Stunnel 4 failing to connect to gmail
by Asif Iqbal 11 Dec '20

11 Dec '20

I am faling to connect to gmail. Not sure what that bind error means. iqbala@ghar:~$ sudo stunnel4 2008.12.15 13:53:17 LOG7[3839:3083650736]: Snagged 64 random bytes from /home/iqbala/.rnd 2008.12.15 13:53:17 LOG7[3839:3083650736]: Wrote 1024 new random bytes to /home/iqbala/.rnd 2008.12.15 13:53:17 LOG7[3839:3083650736]: RAND_status claims sufficient entropy for the PRNG 2008.12.15 13:53:17 LOG7[3839:3083650736]: PRNG seeded successfully 2008.12.15 13:53:17 LOG7[3839:3083650736]: Certificate: /etc/stunnel/stunnel.pem 2008.12.15 13:53:17 LOG7[3839:3083650736]: Certificate loaded 2008.12.15 13:53:17 LOG7[3839:3083650736]: Key file: /etc/stunnel/stunnel.pem 2008.12.15 13:53:17 LOG7[3839:3083650736]: Private key loaded 2008.12.15 13:53:17 LOG7[3839:3083650736]: SSL context initialized for service ssmtp 2008.12.15 13:53:17 LOG5[3839:3083650736]: stunnel 4.22 on i486-pc-linux-gnu with OpenSSL 0.9.8g 19 Oct 2007 2008.12.15 13:53:17 LOG5[3839:3083650736]: Threading:PTHREAD SSL:ENGINE Sockets:POLL,IPv6 Auth:LIBWRAP 2008.12.15 13:53:17 LOG6[3839:3083650736]: file ulimit = 1024 (can be changed with 'ulimit -n') 2008.12.15 13:53:17 LOG6[3839:3083650736]: poll() used - no FD_SETSIZE limit for file descriptors 2008.12.15 13:53:17 LOG5[3839:3083650736]: 500 clients allowed 2008.12.15 13:53:17 LOG7[3839:3083650736]: FD 10 in non-blocking mode 2008.12.15 13:53:17 LOG7[3839:3083650736]: FD 11 in non-blocking mode 2008.12.15 13:53:17 LOG7[3839:3083650736]: FD 12 in non-blocking mode 2008.12.15 13:53:17 LOG7[3839:3083650736]: SO_REUSEADDR option set on accept socket 2008.12.15 13:53:17 LOG3[3839:3083650736]: Error binding ssmtp to 74.125.93.111:587 2008.12.15 13:53:17 LOG3[3839:3083650736]: bind: Cannot assign requested address (99) Here is how my conf file looks like iqbala@ghar:~$ cat /etc/stunnel/stunnel.conf | egrep -v "^;|^$" cert = /etc/stunnel/stunnel.pem foreground = yes sslVersion = SSLv3 chroot = /var/lib/stunnel4/ setuid = stunnel4 setgid = stunnel4 pid = /stunnel4.pid socket = l:TCP_NODELAY=1 socket = r:TCP_NODELAY=1 debug = 7 output = /var/log/stunnel4/stunnel.log client = yes [ssmtp] accept = smtp.gmail.com:587 connect = 25 Asif Iqbal PGP Key: 0xE62693C5 KeyServer: pgp.mit.edu

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Stunnel & Gmail security
by BOXI31 TEST 17 Oct '20

17 Oct '20

Hi all, To make "Stunnel 5.31" work with Gmail, I have to go in security settings of Gmail and "allow less secure apps to access my account". Is it mandatory ? Is it possible to set Stunnel to access Gmail without lowering it security level ? How ? I checked in log file TLS v1.2 is used by Stunnel but Gmail still consider it as a "less secure app." ! Regards, Steve

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PSK mode does not work correctly with TLSv1.3
by Zizhong Zhang 21 Nov '18

21 Nov '18

Hello, In TLSv1.3, session resumption has been reworked to be the same way as PSK. The client attempts resumption by appending a ticket as PSK identity to the head of the list. With OpenSSL 1.1.1, the server side should use the new SSL_CTX_set_psk_find_session_callback() callback instead of SSL_CTX_set_psk_server_callback() which is used by stunnel now. Because stunnel only verifies against the first PSK identity, stunnel will fail for every other connections it makes. This impacts the default configuration when running with OpenSSL 1.1.1 because TLSv1.3 is enabled by default. It may be confusing because only half of the connections will fail as the client will try to resume the last successful session for every second connections. I purpose that stunnel should switch to SSL_CTX_set_psk_find_session_callback() for OpenSSL 1.1.1, and that it preferably should default to a maximum version of TLSv1.2 because it might be compiled with OpenSSL 1.0.x but runs with OpenSSL 1.1.1 which will enable TLSv1.3 automatically. With regards, --Zizhong

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Installing stunnel as a Windows service with another service name?
by Al Birchall 17 Nov '18

17 Nov '18

Hi, Is it possible to install stunnel as a Windows service with another name? I want to have multiple instances of stunnel running on the same Windows 2008 server, if possible. Many thanks. Al

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Server is down
by Paul Muller 13 Nov '18

13 Nov '18

I've installed Stunnel before with no issues. But now I'm getting the following: ] Running on Windows 6.1 [.] Reading configuration from file stunnel.conf [.] UTF-8 byte order mark not detected [.] FIPS mode disabled [ ] Compression disabled [ ] No PRNG seeding was required [ ] Initializing service [SMTP Outgoing] [ ] Ciphers: HIGH:!aNULL:!SSLv2:!DH:!kDHEPSK [ ] TLS options: 0x03000004 (+0x00000000, -0x00000000) [ ] No certificate or private key specified [:] Service [SMTP Outgoing] needs authentication to prevent MITM attacks [.] Configuration successful [ ] Binding service [SMTP Outgoing] [ ] Listening file descriptor created (FD=1388) [ ] Setting accept socket options (FD=1388) [ ] Option SO_EXCLUSIVEADDRUSE set on accept socket [.] Binding service [SMTP Outgoing] to 0.0.0.0:25: Address already in use (WSAEADDRINUSE) (10048) [!] Binding service [SMTP Outgoing] failed [ ] Deallocating section defaults [ ] Unbinding service [SMTP Outgoing] [ ] Service [SMTP Outgoing] closed [ ] Deallocating section [SMTP Outgoing] [!] Server is down Please let me know what I'm doing wrong here. Thank you, [logo1] Paul A. Muller * Systems and Networking Consultant Earnest & Associates * Profitability Improvement Specialists Voice: 305.822.5353 x354 * Fax: 305.822.5848 Email: paul.muller(a)earnestassoc.com<mailto:paul.muller@earnestassoc.com> * Web: earnestassoc.com<http://www.earnestassoc.com/> * Twitter: @earnestassoc<http://twitter.com/earnestassoc>

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Issue with Office365 certificates
by milanimarco82＠libero.it 09 Nov '18

09 Nov '18

Hello, I'm encountering an issue while using sTunnel with an Office365 account. sTunnel worked properly for a few months, while it gived an error with certificates since yesterday, whilst didn't change anything in the configuration. This is our configuration: [pop3s] client = yes accept = 127.0.0.1:2001 connect = outlook.office365.com:995 CAfile = C:\Program Files (x86)\stunnel\config\ca-certs.pem checkHost = outlook.office365.com verifyChain = yes OCSPaia = yes This is what we get in the log: 2018.11.09 11:34:09 LOG7[main]: Found 1 ready file descriptor(s) 2018.11.09 11:34:09 LOG7[main]: FD=432 ifds=r-x ofds=--- 2018.11.09 11:34:09 LOG7[main]: Service [pop3s] accepted (FD=672) from 127.0.0.1:49619 2018.11.09 11:34:09 LOG7[main]: Creating a new thread 2018.11.09 11:34:09 LOG7[main]: New thread created 2018.11.09 11:34:09 LOG7[30]: Service [pop3s] started 2018.11.09 11:34:09 LOG7[30]: Setting local socket options (FD=672) 2018.11.09 11:34:09 LOG7[30]: Option TCP_NODELAY set on local socket 2018.11.09 11:34:09 LOG5[30]: Service [pop3s] accepted connection from 127.0.0.1:49619 2018.11.09 11:34:09 LOG6[30]: failover: priority, starting at entry #0 2018.11.09 11:34:09 LOG6[30]: s_connect: connecting 40.101.9.178:995 2018.11.09 11:34:09 LOG7[30]: s_connect: s_poll_wait 40.101.9.178:995: waiting 10 seconds 2018.11.09 11:34:09 LOG5[30]: s_connect: connected 40.101.9.178:995 2018.11.09 11:34:09 LOG5[30]: Service [pop3s] connected remote server from 172.31.20.23:49620 2018.11.09 11:34:09 LOG7[30]: Setting remote socket options (FD=668) 2018.11.09 11:34:09 LOG7[30]: Option TCP_NODELAY set on remote socket 2018.11.09 11:34:09 LOG7[30]: Remote descriptor (FD=668) initialized 2018.11.09 11:34:09 LOG6[30]: SNI: sending servername: outlook.office365.com 2018.11.09 11:34:09 LOG6[30]: Peer certificate required 2018.11.09 11:34:09 LOG7[30]: TLS state (connect): before/connect initialization 2018.11.09 11:34:09 LOG7[30]: TLS state (connect): SSLv2/v3 write client hello A 2018.11.09 11:34:09 LOG7[30]: TLS state (connect): SSLv3 read server hello A 2018.11.09 11:34:09 LOG7[30]: Verification started at depth=2: C=US, O=DigiCert Inc, OU=www.digicert.com, CN=DigiCert Global Root CA 2018.11.09 11:34:09 LOG7[30]: CERT: Pre-verification succeeded 2018.11.09 11:34:09 LOG7[30]: OCSP: Ignoring root certificate 2018.11.09 11:34:09 LOG6[30]: Certificate accepted at depth=2: C=US, O=DigiCert Inc, OU=www.digicert.com, CN=DigiCert Global Root CA 2018.11.09 11:34:09 LOG7[30]: Verification started at depth=1: C=US, O=DigiCert Inc, CN=DigiCert Cloud Services CA-1 2018.11.09 11:34:09 LOG7[30]: CERT: Pre-verification succeeded 2018.11.09 11:34:09 LOG5[30]: OCSP: Connecting the AIA responder "http://ocsp.digicert.com" 2018.11.09 11:34:09 LOG6[30]: s_connect: connecting 93.184.220.29:80 2018.11.09 11:34:09 LOG7[30]: s_connect: s_poll_wait 93.184.220.29:80: waiting 10 seconds 2018.11.09 11:34:09 LOG5[30]: s_connect: connected 93.184.220.29:80 2018.11.09 11:34:09 LOG7[30]: OCSP: Connected ocsp.digicert.com:80 2018.11.09 11:34:09 LOG7[30]: OCSP: Response received 2018.11.09 11:34:09 LOG6[30]: OCSP: Status: good 2018.11.09 11:34:09 LOG6[30]: OCSP: This update: Nov 9 00:00:00 2018 GMT 2018.11.09 11:34:09 LOG6[30]: OCSP: Next update: Nov 16 00:00:00 2018 GMT 2018.11.09 11:34:09 LOG5[30]: OCSP: Certificate accepted 2018.11.09 11:34:09 LOG6[30]: Certificate accepted at depth=1: C=US, O=DigiCert Inc, CN=DigiCert Cloud Services CA-1 2018.11.09 11:34:09 LOG7[30]: Verification started at depth=0: C=US, ST=Washington, L=Redmond, O=Microsoft Corporation, CN=outlook.com 2018.11.09 11:34:09 LOG7[30]: CERT: Pre-verification succeeded 2018.11.09 11:34:09 LOG6[30]: CERT: Host name "outlook.office365.com" matched with "*.office365.com" 2018.11.09 11:34:09 LOG5[30]: OCSP: Connecting the AIA responder "http://ocspx.digicert.com" 2018.11.09 11:34:09 LOG6[30]: s_connect: connecting 93.184.220.29:80 2018.11.09 11:34:09 LOG7[30]: s_connect: s_poll_wait 93.184.220.29:80: waiting 10 seconds 2018.11.09 11:34:09 LOG5[30]: s_connect: connected 93.184.220.29:80 2018.11.09 11:34:09 LOG7[30]: OCSP: Connected ocspx.digicert.com:80 2018.11.09 11:34:09 LOG7[30]: OCSP: Response received 2018.11.09 11:34:09 LOG3[30]: OCSP: Responder error: 6: unauthorized 2018.11.09 11:34:09 LOG4[30]: Rejected by OCSP at depth=0: C=US, ST=Washington, L=Redmond, O=Microsoft Corporation, CN=outlook.com 2018.11.09 11:34:09 LOG7[30]: TLS alert (write): fatal: handshake failure 2018.11.09 11:34:09 LOG3[30]: SSL_connect: 14090086: error:14090086:SSL routines:ssl3_get_server_certificate:certificate verify failed 2018.11.09 11:34:09 LOG5[30]: Connection reset: 0 byte(s) sent to TLS, 0 byte(s) sent to socket 2018.11.09 11:34:09 LOG7[30]: Deallocating application specific data for session connect address 2018.11.09 11:34:09 LOG7[30]: Remote descriptor (FD=668) closed 2018.11.09 11:34:09 LOG7[30]: Local descriptor (FD=672) closed 2018.11.09 11:34:09 LOG7[30]: Service [pop3s] finished (0 left) Can you please help me? Thanks in advance!

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Please need urgent help
by Alix Janeth Jerez 09 Nov '18

09 Nov '18

Hi, I have installed the last stunnel version 5.4.9, i get this fatal error [cid:60207984-5796-4d47-986e-21551ff82966] The stunnel.conf is configured so: debug = 7 output = stunnel.log # GLOBAL OPTIONS client = yes taskbar=yes [SMTP Outgoing] protocol = smtp accept = 172.31.41.84:117 connect = smtp.outlook.com:587 checkHost = smtp.outlook.com verifyChain = yes CAfile = ca-certs.pem OCSPaia = yes cert = stunnel.pem I tried to enable this option ; Enable support for the insecure SSLv3 protocol options = -NO_SSLv3 But stunnel does't work. Thank you in advance for your help. Best regards,

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