November 2024 - 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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stunnel - client conexion close by TLS alert (write) fatal decode error
by Rodigo Alvarez 07 Mar '25

07 Mar '25

Hi All! I would appreciate any clue to solve the problem we are having with a client mode service that stopped working this week (we verified that the service works directly without stunnel). The error I identify in the trace is the following: "TLS alert (write): fatal: decode error" Stunnel Config (windows version): [afip-prod-fce] client = yes accept = ARSASSRV4DMS06:1031 connect = serviciosjava.afip.gob.ar:443 debug = 7 ws: https://serviciosjava.afip.gob.ar/wsfecred/FECredService Complete trace: 2024.01.24 09:28:46 LOG5[main]: stunnel 5.71 on x64-pc-mingw32-gnu platform 2024.01.24 09:28:46 LOG5[main]: Compiled/running with OpenSSL 3.1.3 19 Sep 2023 2024.01.24 09:28:46 LOG5[main]: Threading:WIN32 Sockets:SELECT,IPv6 TLS:ENGINE,OCSP,PSK,SNI 2024.01.24 09:28:46 LOG5[main]: Reading configuration from file C:\Program Files (x86)\stunnel\config\stunnel.conf 2024.01.24 09:28:46 LOG5[main]: UTF-8 byte order mark detected 2024.01.24 09:28:46 LOG5[main]: FIPS mode disabled 2024.01.24 09:28:46 LOG4[main]: Service [afip-prod-fce] needs authentication to prevent MITM attacks 2024.01.24 09:28:46 LOG5[main]: Configuration successful 2024.01.24 09:29:23 LOG7[0]: Service [afip-prod-fce] started 2024.01.24 09:29:23 LOG7[0]: Setting local socket options (FD=892) 2024.01.24 09:29:23 LOG7[0]: Option TCP_NODELAY set on local socket 2024.01.24 09:29:23 LOG5[0]: Service [afip-prod-fce] accepted connection from 10.70.162.24:57723 2024.01.24 09:29:23 LOG6[0]: s_connect: connecting 200.1.116.19:443 2024.01.24 09:29:23 LOG7[0]: s_connect: s_poll_wait 200.1.116.19:443: waiting 10 seconds 2024.01.24 09:29:23 LOG7[0]: FD=896 ifds=rwx ofds=--- 2024.01.24 09:29:24 LOG5[0]: s_connect: connected 200.1.116.19:443 2024.01.24 09:29:24 LOG5[0]: Service [afip-prod-fce] connected remote server from 10.72.0.69:64788 2024.01.24 09:29:24 LOG7[0]: Setting remote socket options (FD=896) 2024.01.24 09:29:24 LOG7[0]: Option TCP_NODELAY set on remote socket 2024.01.24 09:29:24 LOG7[0]: Remote descriptor (FD=896) initialized 2024.01.24 09:29:24 LOG6[0]: SNI: sending servername: serviciosjava.afip.gob.ar 2024.01.24 09:29:24 LOG6[0]: Peer certificate not required 2024.01.24 09:29:24 LOG7[0]: TLS state (connect): before SSL initialization 2024.01.24 09:29:24 LOG7[0]: Initializing application specific data for session authenticated 2024.01.24 09:29:24 LOG7[0]: TLS state (connect): SSLv3/TLS write client hello 2024.01.24 09:29:24 LOG7[0]: TLS state (connect): SSLv3/TLS write client hello 2024.01.24 09:29:24 LOG7[0]: TLS state (connect): SSLv3/TLS read server hello 2024.01.24 09:29:24 LOG6[0]: CERT: Certificate verification disabled 2024.01.24 09:29:24 LOG6[0]: CERT: Certificate verification disabled 2024.01.24 09:29:24 LOG6[0]: CERT: Certificate verification disabled 2024.01.24 09:29:24 LOG7[0]: TLS state (connect): SSLv3/TLS read server certificate 2024.01.24 09:29:24 LOG7[0]: TLS state (connect): SSLv3/TLS read server key exchange 2024.01.24 09:29:24 LOG7[0]: OCSP stapling: Client callback called 2024.01.24 09:29:24 LOG6[0]: OCSP: Certificate chain verification disabled 2024.01.24 09:29:24 LOG6[0]: Client certificate not requested 2024.01.24 09:29:24 LOG7[0]: TLS state (connect): SSLv3/TLS read server done 2024.01.24 09:29:24 LOG7[0]: TLS state (connect): SSLv3/TLS write client key exchange 2024.01.24 09:29:24 LOG7[0]: TLS state (connect): SSLv3/TLS write change cipher spec 2024.01.24 09:29:24 LOG7[0]: TLS state (connect): SSLv3/TLS write finished 2024.01.24 09:29:24 LOG7[0]: TLS state (connect): SSLv3/TLS write finished 2024.01.24 09:29:24 LOG7[0]: TLS state (connect): SSLv3/TLS read change cipher spec 2024.01.24 09:29:24 LOG7[0]: TLS state (connect): SSLv3/TLS read finished 2024.01.24 09:29:24 LOG7[0]: New session callback 2024.01.24 09:29:24 LOG7[0]: Peer certificate was cached (6643 bytes) 2024.01.24 09:29:24 LOG6[0]: Session id: D63C79766AC02C9A3E8494AD528954A183E9F7C250856695BA05C16A2219A4B3 2024.01.24 09:29:24 LOG7[0]: 1 client connect(s) requested 2024.01.24 09:29:24 LOG7[0]: 1 client connect(s) succeeded 2024.01.24 09:29:24 LOG7[0]: 0 client renegotiation(s) requested 2024.01.24 09:29:24 LOG7[0]: 0 session reuse(s) 2024.01.24 09:29:24 LOG6[0]: TLS connected: new session negotiated 2024.01.24 09:29:24 LOG6[0]: TLSv1.2 ciphersuite: ECDHE-RSA-AES128-GCM-SHA256 (128-bit encryption) 2024.01.24 09:29:24 LOG6[0]: Peer temporary key: ECDH, P-256, 256 bits 2024.01.24 09:29:24 LOG7[0]: Compression: null, expansion: null 2024.01.24 09:29:24 LOG7[0]: Remove session callback 2024.01.24 09:29:24 LOG7[0]: TLS alert (write): fatal: decode error 2024.01.24 09:29:24 LOG6[0]: TLS socket closed (SSL_read) 2024.01.24 09:29:24 LOG7[0]: Sent socket write shutdown 2024.01.24 09:29:24 LOG5[0]: Connection closed: 1755 byte(s) sent to TLS, 634 byte(s) sent to socket 2024.01.24 09:29:24 LOG7[0]: Remote descriptor (FD=896) closed 2024.01.24 09:29:24 LOG7[0]: Local descriptor (FD=892) closed 2024.01.24 09:29:24 LOG7[0]: Service [afip-prod-fce] finished (0 left) Thank you! Kind regards, Rodrigo.

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Router + Cudy mesh system
by trashrap22＠gmail.com 26 Nov '24

26 Nov '24

Hi, My stunnel setup was working. I since moved and had to add a Cudy mesh system / extension to the router to extend the internet through the building. Now I can't get stunnel to work again - I have done port forwarding on the Cudy system too. Has anyone done this extentions of router setup and got stunnel to work?

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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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Is it possible to hide "Acceptable client certificate CA names" during SSL handshaking?
by hshh 12 Nov '24

12 Nov '24

Since version 5.68, when stunnel is configured with verifyPeer=yes, CApath=/path and CAfile=/path/file, the 'Acceptable client certificate CA names' and required certificates are displayed during SSL handshaking. Is it possible to hide this information?

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s_ssl_read_eof: SSL_ERROR_WANT_READ: Retrying
by stavultras＠gmail.com 07 Nov '24

07 Nov '24

Hello, i've encountered a very strange issue when you use stunnel 7.53 (doesn't matter actually, happens in 5.68 as well) like this: [server] accept = 443 protocol = socks [client] accept = 1080 protocol = socks connect = server:443 with iptables -A OUTPUT -p tcp -d 10.8.0.1 -j REDIRECT --to-ports 1080, I see in 95% cases in logs for every request from curl: curl http://10.8.0.1 (server's internal IP), however, it never happens if you use client like this: [client] accept = 1080 connect = server:443 and curl -x socks5://127.0.0.1:1080 http://10.8.0.1 (internal server's IP). Technically it affects nothing, but I still guess there's a small time overhead due to retry. Maybe i'm wrong. Please advise. Thanks.

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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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socks mode doesn't verify peer
by stavultras＠gmail.com 05 Nov '24

05 Nov '24

Hello. I'm trying to configure "protocol = socks" with "redirect = 127.0.0.1:80" and "verifyPeer = yes", but accordingly to the debug logs stunnel doesn't verify peer when I'm trying to connect without client's certificate, for an example, from browser: https://192.168.200.131:9013/, where 192.168.200.131 is stunnel server. Config file: [socks] cert = /usr/local/etc/stunnel/server.pem CAfile = /usr/local/etc/stunnel/client.crt verifyPeer = yes redirect = 127.0.0.1:80 accept = 0.0.0.0:9013 protocol = socks Debug log: 2024.10.02 07:24:19 LOG6[9]: No peer certificate received 2024.10.02 07:24:19 LOG6[9]: Session id: AFA5F9CE2997328612F76E3B3572FE00C71C53ED31A98567E56DCC084EF580AD 2024.10.02 07:24:19 LOG7[9]: TLS state (accept): SSLv3/TLS write session ticket 2024.10.02 07:24:19 LOG6[9]: TLS accepted: new session negotiated 2024.10.02 07:24:19 LOG6[9]: TLSv1.3 ciphersuite: TLS_AES_128_GCM_SHA256 (128-bit encryption) 2024.10.02 07:24:19 LOG6[9]: Peer temporary key: X25519, 253 bits 2024.10.02 07:24:19 LOG7[9]: Compression: null, expansion: null 2024.10.02 07:24:19 LOG7[9]: Waiting for the SOCKS request 2024.10.02 07:24:19 LOG3[9]: Unsupported SOCKS version 0x47 2024.10.02 07:24:19 LOG5[9]: Connection reset: 0 byte(s) sent to TLS, 0 byte(s) sent to socket It tries to accept SOCKS info even without certificate and doesn't redirect to 127.0.0.1:80. In browser, I'm getting: Secure Connection Failed An error occurred during a connection to 192.168.200.131:9013. PR_CONNECT_RESET_ERROR Error code: PR_CONNECT_RESET_ERROR Can you check why it happens? Thank you.

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"direct" protocol support
by stavultras＠gmail.com 05 Nov '24

05 Nov '24

Hello, is it possible to implement "direct" protocol support? For an example: You have OpenVPN TCP on a server and let's say SSH (or any other TCP software) and you want to use stunnel on the same port or under the same SNI. Configs would like: [server] accept = 443 protocol = direct [client_openvpn_tcp] sni=test.com protocolHost = 127.0.0.1:2000 connect = server:443 accept = 127.0.0.1:2000 [client_ssh] sni=test.com protocolHost = 127.0.0.1:22 connect = server:443 accept = 127.0.0.1:222 I know, you can use "protocol = socks", but in this case you can't use this thing directly with your software that doesn't support socks5 (OpenVPN isn't a fully good example, because it supports socks5 proxy). SSH is a good example if you want to use it under TLS on the same port with OpenVPN TCP and other TCP applications. It will be useful for many other applications without socks5 support and if you won't occupy more than 1 port or SNI. P.S.: I'm still trying to use socks5 code from stunnel to implement "direct" protocol, but i'm not very good at C. Thanks.

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