April 2019 - 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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older browsers, stunnel and privoxy
by kovacs janos 04 Mar '24

04 Mar '24

sorry to bother, im trying to make older browsers be able to display TLS 1.1 and TLS 1.2 sites. i heard stunnel cant be configured to always forward to the current site address dynamically, thats why i would use privoxy. the browser is configured to send to: 127.0.0.1 443 stunnel config has this at the end: [Tunnel_in] client = yes accept = 127.0.0.1:443 connect = 127.0.0.1:8118 verifyChain = yes CAfile = ca-certs.pem checkHost = localhost 127.0.0.1:8118 is the privoxy address. this is what stunnel writes: LOG5[main]: Configuration successful LOG5[0]: Service [Tunnel_in] accepted connection from 127.0.0.1:3261 LOG5[0]: s_connect: connected 127.0.0.1:8118 LOG5[0]: Service [Tunnel_in] connected remote server from 127.0.0.1:3262 and the browser infinitely loads, and never loads anything or leaves the page. if i remove the last 3 lines, its the same just with this line added: LOG4[main]: Service [Tunnel_in] needs authentication to prevent MITM attacks but it doesnt give an error or anything. with a configuration like: [Tunnel_out] client = no accept = 127.0.0.1:443 connect = 127.0.0.1:8118 cert = stunnel.pem this is what it gives: LOG5[3]: Service [Tunnel_out] accepted connection from 127.0.0.1:3294 LOG3[3]: SSL_accept: 1407609B: error:1407609B:SSL routines:SSL23_GET_CLIENT_HELLO:https proxy request LOG5[3]: Connection reset: 0 byte(s) sent to TLS, 0 byte(s) sent to socket and browser gives a server not found error immediately. im not even sure if i should use client or server configuration in a case like this, but none of them works anyway. all i would need is for my browser to get the pages decrypted, or at least in less than TLS1.1. like how on newipnow.com i can access sites with any encryption, since they are sent to the browser without encryption. the browser just gives an "unencrypted tunnel" warning, which is how i found stunnel, and which is exactly what i need, just locally.

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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] illegal instruction crash 5.50 Debian/Stretch
by Michal Trojnara 29 Apr '19

29 Apr '19

On 24.04.2019 16:06, Florian Lohoff wrote: > with the stunnel4 in Debian/Stretch i am experiencing pretty regular > crashes with illegal instruction. Version is 5.50. > In Bug https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=880659 > you can see the drill down to a Lock beeing unlocked although > not locked. When i look at the code its some usage of openssl > primitives. (Unlock happens in openssl code) > I had a quick look at the changelog and this: > "Service threads are terminated before OpenSSL cleanup to prevent occasional stunnel crashes at shutdown." > sounds a bit like the issue i am experiencing. > Can you confirm this? Yes, I do confirm this is the issue described in the Debian bug #880659. It wasn't a simple coding error, but rather a design flaw introduced in version 3.0 that took 20 years to identify and fix. Before version 5.18, released almost 4 years ago, the shutdown race condition mostly manifested itself while terminating stunnel under extremely heavy load, such as stress testing. The probability has increased with the introduction of periodic DH parameter regeneration in version 5.18. I didn't test it, but I suspect some changes in the OpenSSL internals may have also cause the crashes to only surface fairly recently, and not 20 years ago. The fix itself involves a major redesign of the stunnel threading subsystem, so I made a beta version and I'd appreciate your help with testing it: https://www.stunnel.org/downloads/beta/stunnel-5.54b2.tar.gz Best regards, Mike

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Either "verifyChain" or "verifyPeer" has to be enabled
by kovacs janos 23 Apr '19

23 Apr '19

sorry to bother, again this is probably something simple, but i couldn't find anything about it. i'm trying to make stunnel NOT verify the certificate of the address it connects to. specifically because the certificate date will give an error, and i know its safe to connect there. whenever i put 'verify = 0' or 'verifyChain = no' or 'verifyPeer = no' in the configuration, i get an error saying 'Either "verifyChain" or "verifyPeer" has to be enabled', and so the configuration can't be applied. and i found nothing about this anywhere. or this could only be set on server Services? and there is no way to not verify if 'client = yes'?

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Stunnel 5.44 client syntax to accept connections on pty?
by Martin Got 18 Apr '19

18 Apr '19

How to use 'stunnel' in client mode to accept connections on pty from local programs like 'ppp' instead of 'accept=IP:PORT'? 'pty = yes' seems work in server mode only, so when I removed 'accept = 127.0.0.1:1723' from 'stunnel' client config I'm getting the error: [!] Service [ppp]: Each service must define two endpoints on stunnel-5.44 I need to call 'stunnel' client from 'pppd' and communicate with 'stunnel' using pty if it was possible by using a command: pppd /dev/ptyp3 10.0.1.2: local debug noauth passive noccp novj novjccomp nopcomp noaccomp name ppp-client connect 'stunnel /etc/stunnel/stunnel-client.conf' Both 'pppd' and 'stunnel' started by executing the command above, but 'pppd' can't communicate to 'stunnel' server using pty. Please advice. [ppp] client = yes accept = [127.0.0.1:1723 ](http://127.0.0.1:1723) ^^^^^^^^^^^^^^^^^^^^^^^ connect = STUNNEL-SERVER-IP:723 CAfile = /etc/stunnel/ca.crt cert = /etc/stunnel/client.crt key = /etc/stunnel/client.key verifyChain = yes checkHost = hostna.me ;checkIP = 1.2.3.4

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Sending original IP (proxy) for smtp
by James Brown 16 Apr '19

16 Apr '19

I’d like stunnel to pass the incoming IP along, not stunnel's IP. My traffic flow is: Stunnel (accept on port 465) -> ASSP (an smtp proxy) -> Postfix (accept on port 10026) I tried: [ssmtp] client = no accept = 465 connect = 25 protocol = proxy But ASSP had: Apr-15-19 18:50:22 [Worker_1] Connected: session:7FE104AA1870 127.0.0.1:58954 > 127.0.0.1:25 > 127.0.0.1:10026 Apr-15-19 18:50:23 [Worker_1] 127.0.0.1 warning: got reply '502 5.5.2 Error: command not recognized' from 127.0.0.1 Apr-15-19 18:50:23 id-18223-03317 [Worker_1] 127.0.0.1 info: sending EHLO instead of HELO to 127.0.0.1 Apr-15-19 18:50:23 id-18223-03317 [Worker_1] 127.0.0.1 disconnected: session:7FE104AA1870 127.0.0.1 - processing time 1 seconds And Postfix had: 2019-04-15 18:50:22.995042+1000 localhost smtpd[33360]: connect from localhost[127.0.0.1] 2019-04-15 18:50:23.108756+1000 localhost smtpd[33360]: improper command pipelining after EHLO from localhost[127.0.0.1]: RSET\r\n 2019-04-15 18:50:23.273664+1000 localhost smtpd[33360]: disconnect from localhost[127.0.0.1] ehlo=2 rset=1 quit=1 unknown=0/1 commands=4/5 So I take it protocol=proxy is not the way to do it. Sounds like this only works with haproxy which I do not have installed. Is there a way to do this? The problem I am trying to solve is ASSP has lines like: warning: SMTP authentication failed on 127.0.0.1 - obviously I don’t want fail2ban to ban 127.0.0.1. Stunnel log has: 2019.04.15 18:52:26 LOG5[23]: Service [ssmtp] accepted connection from ::ffff:185.222.209.66:53642 2019.04.15 18:52:27 LOG3[23]: s_connect: connect ::1:25: Connection refused (61) Any suggestions? Thanks, James.

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