October 2017 - 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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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 16 Oct '20

16 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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Re: [stunnel-users] How to distinguish stunnel definition between SMTP through SSL-TLS vs. STARTTLS?
by Harris, Douglas (SSC/SPC) 26 Oct '17

26 Oct '17

> Ok, if I specify > > protocol=smtp > > what does that mean: "Connect through SSL-TLS protocol" or "connect through STARTTLS protocol"? That means connect using STARTTLS. > It seems to me that I ALWAYS have to specify "protocol=smtp" for ALL smtp-server connects. You don't. If you are not using STARTTLS you don't specify "protocol=". > Is this done only by port number 465 vs 587? No. > That would mean there is a hidden configuration by convention! Indeed. That would be bad. > What if the webhoster would set up a special mail server at port 8888? Then you would specify port 8888 in your "connect=" config

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How to distinguish stunnel definition between SMTP through SSL-TLS vs. STARTTLS?
by Ben Stover 26 Oct '17

26 Oct '17

As yyou know there are two types of letting a local email client connect to remote secured SMTP server: 1.) through SSL-TLS and 2.) through STARTTLS How do I distinguish betwen these connection types in the stunnel.conf setup file? In a previous post I was told to look at the "protocol" parameter. Ok, if I specify protocol=smtp what does that mean: "Connect through SSL-TLS protocol" or "connect through STARTTLS protocol"? It seems to me that I ALWAYS have to specify "protocol=smtp" for ALL smtp-server connects. The stunnel documentation does not explain how to setup the *.conf file for each of the variants. Is this done only by port number 465 vs 587? That would mean there is a hidden configuration by convention! What if the webhoster would set up a special mail server at port 8888? Ben

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stunnel and TLS1.2 for IE
by Thomas GMX 20 Oct '17

20 Oct '17

Hello. I have successfully configured my email client (Outlook 2010) to my provider with TLS1.2 via stunnel running as a service. config: debug = 5 engine = capi [freenet-pop3s] client = yes EngineID = capi accept = localhost:2110 connect = mx.freenet.de:995 [freenet-smpts] client = yes EngineID = capi accept = localhost:2025 connect = mx.freenet.de:465 That was no problem. But at this point I am wondering if it is possible and how I can configure stunnel so that "all" https traffic from Internet Explorer is going through stunnel and connect to internet with highest secure level supported. Not only to one specific server (connect = xyz.net) but to all servers given in IE address. By now I guess that I have to set IE so that it uses a https-proxy at "localhost:xxx" with stunnel config "accept = localhost:xxx". But how is stunnel config for "connect x.x.x.x:443" that it connect to the right server in internet I specified in IE address line? Can someone give me a hint? Or impossible? Thanks a lot Thomas

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Connection setup for STARTTLS vs. SSL/TLS for POP3/SMTP mail servers?
by Ben Stover 20 Oct '17

20 Oct '17

In stunnels *.conf file I can specify the mail server name and the port for a connection. How can I tell stunnel to use STARTTLS as connect type? How can I tell stunnel to use SSL/TLS as connect type? Does stunnel support both connect types at all or only one? Is the connect type for SMTP completely determined by port e.g.: STARTTLS over port 587 and SSL/TLS over port 465 or can both connect types use both ports? Assume I do not get the supported connect type information from my webhoster: How can I find it out from my (client) side? What are there error messages? Ben

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Stunnel on Android 7.x not working?
by John Appleseed 14 Oct '17

14 Oct '17

Hello, I have trouble with stunnel on Android 7.x.. I'm trying to connect to OpenVPN server through SSL tunneling with stunnel. On phone I'm using stunnel installed in Termux and OpenVPN. Everything is correctly configured, Im using the same config on other devices in same network and it works perfectly. I tried it with different devices with Android 7.x and it is not working at all :( Immediately after succesful connection I am receiving: TLS fd: Software caused connection abort (103) TLS socket closed (SSL_read) And it is still reconnecting again and again with the same error. I also tried it with stunnel downloaded directly from stunnel.org site.. Anyone with new Android who have working stunnel? Where can be the problem? Example stunnel.conf on Android: socket = l:TCP_NODELAY=1 socket = r:TCP_NODELAY=1 debug = debug [openvpn] client = yes accept = 1337 connect = *****.ddns.net:993 cert = /path/to/stunnel.pem and on server: chroot = /var/lib/stunnel4 pid = /stunnel.pid output = /stunnel.log setuid = stunnel4 setgid = stunnel4 socket = l:TCP_NODELAY=1 socket = r:TCP_NODELAY=1 [openvpn] client = no accept = 993 connect = 127.0.0.1:1194 cert = /etc/stunnel/stunnel.pem Example stunnel.log is in attachment. Thank you very much

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No certificate or private key specified
by Hugo Darley 12 Oct '17

12 Oct '17

Hi, After overcoming some initial more obvious problems I have still been unable to get this client's stunnel configured correctly. "No certificate or private key specified" - is this significant? Stunnel.conf looks like the below: debug = 2 output = stunnel.log CAfile=.\ca-verisign.crt client=yes verify=0 sslVersion = TLSv1.2 options = NO_SSLv2 options = NO_SSLv3 [TRD] accept=16002 connect= our.ip.com:443 [INV] accept=16003 connect= our.ip.com:443 Stunnel output log below 2017.10.12 10:53:22 LOG7[main]: Found 1 ready file descriptor(s) 2017.10.12 10:53:22 LOG7[main]: FD=276 ifds=r-x ofds=--- 2017.10.12 10:53:22 LOG7[main]: FD=284 ifds=r-x ofds=--- 2017.10.12 10:53:22 LOG7[main]: Dispatching signals from the signal pipe 2017.10.12 10:53:22 LOG7[main]: Processing SIGNAL_RELOAD_CONFIG 2017.10.12 10:53:22 LOG7[main]: Running on Windows 6.1 2017.10.12 10:53:22 LOG5[main]: Reading configuration from file stunnel.conf 2017.10.12 10:53:22 LOG5[main]: UTF-8 byte order mark detected 2017.10.12 10:53:22 LOG5[main]: FIPS mode disabled 2017.10.12 10:53:22 LOG7[main]: Compression disabled 2017.10.12 10:53:22 LOG7[main]: Snagged 64 random bytes from C:/.rnd 2017.10.12 10:53:22 LOG7[main]: Wrote 1024 new random bytes to C:/.rnd 2017.10.12 10:53:22 LOG7[main]: PRNG seeded successfully 2017.10.12 10:53:22 LOG6[main]: Initializing service [TRD] 2017.10.12 10:53:22 LOG7[main]: Ciphers: HIGH:!DH:!aNULL:!SSLv2 2017.10.12 10:53:22 LOG7[main]: TLS options: 0x03000004 (+0x03000000, -0x00000000) 2017.10.12 10:53:22 LOG7[main]: No certificate or private key specified 2017.10.12 10:53:22 LOG4[main]: Service [TRD] needs authentication to prevent MITM attacks 2017.10.12 10:53:22 LOG6[main]: Initializing service [INV] 2017.10.12 10:53:22 LOG7[main]: Ciphers: HIGH:!DH:!aNULL:!SSLv2 2017.10.12 10:53:22 LOG7[main]: TLS options: 0x03000004 (+0x03000000, -0x00000000) 2017.10.12 10:53:22 LOG7[main]: No certificate or private key specified 2017.10.12 10:53:22 LOG4[main]: Service [INV] needs authentication to prevent MITM attacks 2017.10.12 10:53:22 LOG5[main]: Configuration successful 2017.10.12 10:53:22 LOG7[main]: Closing service [TRD] 2017.10.12 10:53:22 LOG7[main]: Service [TRD] closed (FD=284) 2017.10.12 10:53:22 LOG7[main]: Service [TRD] closed 2017.10.12 10:53:22 LOG7[main]: Closing service [INV] 2017.10.12 10:53:22 LOG7[main]: Service [INV] closed (FD=276) 2017.10.12 10:53:22 LOG7[main]: Service [INV] closed We tried giving the certification a hard location but still it seems unable to find it. Is there anything in the cfg you can see missing? Bearing in mind this is standard cfg for our clients connecting in. Kind regards, Hugo Darley The information contained in and accompanying this communication is strictly confidential and intended solely for the use of the intended recipient(s). If you have received it by mistake please let us know by reply and then delete it from your system; you should not copy the message or disclose its content to anyone. MarketAxess reserves the right to monitor the content of emails sent to or from its systems. Any comments or statements made are not necessarily those of MarketAxess. For more information, please visit www.marketaxess.com. MarketAxess Europe Limited is authorised and regulated by the UK Financial Conduct Authority, registered in England no. 4017610, registered office at 5 Aldermanbury Square, London EC2V 7HR. Telephone (020) 7709 3100. MarketAxess Corporation is regulated in the USA by the SEC and FINRA, incorporated in Delaware, executive offices at 299 Park Avenue, New York, NY 10171. Telephone (1) 212 813 6000.

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