- stunnel-users - stunnel.org

Is TLS 1.2 supported with stunnel 5.01
by joverton＠vital-soft.com 01 Jun '25

01 Jun '25

I have searched online, but was unable to fine any definitive answer on the minimum version of stunnel required for TLS 1.2. I have a client using stunnel 5.01 with our solution and they want to activate TLS 1.2. Their setup looks like this: 2014.05.15 13:38:22 LOG5[10132]: stunnel 5.01 on x86-pc-msvc-1500 platform 2014.05.15 13:38:22 LOG5[10132]: Compiled/running with OpenSSL 1.0.1g-fips 7 Apr 2014 2014.05.15 13:38:22 LOG5[10132]: Threading:WIN32 Sockets:SELECT,IPv6 SSL:ENGINE,OCSP,FIPS 2014.05.15 13:38:22 LOG5[10132]: Reading configuration from file stunnel.conf 2014.05.15 13:38:22 LOG5[10132]: FIPS mode disabled 2014.05.15 13:38:22 LOG5[10132]: Configuration successful Everything works fine without requiring TLS 1.2, but when that is required, we get the following error: 2025.05.14 07:04:45 LOG7[3796]: SSL state (connect): before/connect initialization 2025.05.14 07:04:45 LOG7[3796]: SSL state (connect): SSLv3 write client hello A 2025.05.14 07:04:45 LOG7[3796]: SSL alert (read): fatal: protocol version 2025.05.14 07:04:45 LOG3[3796]: SSL_connect: 1409442E: error:1409442E:SSL routines:SSL3_READ_BYTES:tlsv1 alert protocol version 2025.05.14 07:04:45 LOG5[3796]: Connection reset: 0 byte(s) sent to SSL, 0 byte(s) sent to socket 2025.05.14 07:04:45 LOG7[3796]: Remote socket (FD=840) closed 2025.05.14 07:04:45 LOG7[3796]: Local socket (FD=832) closed - Do we need to change anything in stunnel.conf? - Do we need to upgrade stunnel? Many Thanks, John

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Re: stunnel 5.75 released
by Christian Ullrich 28 May '25

28 May '25

* Michal Trojnara wrote: > I have released version 5.75 of stunnel. > > ### Version 5.75, 2025.05.26, urgency: MEDIUM Hello, why does the Windows release include "libgcc_s_seh-1.dll"? I cannot find anything that uses it, and a basic configuration works without any attempts to load it. I went to some lengths to find indications it might be loaded dynamically, but found nothing. Thanks, -- Christian

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stunnel 5.75 released
by Michał Trojnara 26 May '25

26 May '25

Dear Users, I have released version 5.75 of stunnel. ### Version 5.75, 2025.05.26, urgency: MEDIUM * Security bugfixes - OpenSSL DLLs updated to version 3.4.1. - OpenSSL FIPS Provider updated to version 3.1.2. * Bugfixes - Fixed infinite loop triggered by OCSP URL parsing errors (thx to Richard Könning for reporting). - Fixed OPENSSL_NO_OCSP build issues (thx to Dmitry Mostovoy for reporting). - Fixed default curve selection in FIPS mode with OpenSSL 3.4+. - Fixed tests with modern Python versions. - Fixed tests with multiple OpenSSL versions installed. * Features - Added provider URI support for "cert" and "key" options. - Added new "CAstore" service-level option (OpenSSL 3.0+). - Added "provider" (OpenSSL 3.0+), "providerParameter" (OpenSSL 3.5+), and "setEnv" global options. - Key file/URI path added to passphrase prompt on Unix. - PKCS#11 provider installed on Windows. Home page: https://www.stunnel.org/ Download: https://www.stunnel.org/downloads.html SHA-256 hashes: 0c1ef0ed85240974dccb94fe74fb92d6383474c7c0d10e8796d1f781a3ba5683 stunnel-5.75.tar.gz 18ec3b83bda9143c79479ecdc1e3ecf515eeb8a8b11e6ea3a6856cd77399317d stunnel-5.75-win64-installer.exe d1a04ec51840d8cbf5fb6d897d2eb999af573b5b66268fdec109cddaff2acfb7 stunnel-5.75-android.zip Best regards, Mike

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Preserving Client IP Address
by atritium＠hushmail.com 21 May '25

21 May '25

Has anyone followed the stunnel man page instructions and been able to successfully pass/preserve the connecting client's original IP address? Checking history on this issue back to 2010, it looks people with problems, no reports of success. Though it seems so fundamental, you would hope it was smooth as the man page indicates For example, I set up an iptables 'mangle' table for DIVERT routing, ip rule, ip route, etc, for the server as given in the stunnel man page for a Red Hat 8 system. When the stunnel server is then also configured with "transparent = source" and restarted, the remote-initiated connection -hangs- without connecting for a few seconds before closing. Take out "transparent = source" from the server config, and the connection works successfully (though the client IP address is not available to applications). Logs are the same up until the point (shown below), which shows the "hanging/failed" case timing out after reporting "Cannot assign an AF=2 address an AF=10 socket". Don't know what the "Cannot assign AF ..." refers to, or how to address it, but the process goes downhill and hangs after that. 7111 is the open port stunnel is monitoring. 2025.05.21 10:07:16 LOG7[0]: Cannot assign an AF=2 address an AF=10 socket 2025.05.21 10:07:16 LOG6[0]: IP_TRANSPARENT socket option set 2025.05.21 10:07:16 LOG6[0]: bind succeeded on the original port 2025.05.21 10:07:16 LOG6[0]: s_connect: connecting 127.0.0.1:7111 2025.05.21 10:07:16 LOG7[0]: s_connect: s_poll_wait 127.0.0.1:7111: waiting 10 seconds 2025.05.21 10:07:16 LOG7[0]: FD=6 events=0x2001 revents=0x0 2025.05.21 10:07:16 LOG7[0]: FD=11 events=0x2005 revents=0x1 2025.05.21 10:07:26 LOG3[0]: s_connect: s_poll_wait 127.0.0.1:7111: TIMEOUTconnect exceeded 2025.05.21 10:07:26 LOG3[0]: No more addresses to connect 2025.05.21 10:07:26 LOG5[0]: Connection reset: 0 byte(s) sent to TLS, 0 byte(s) sent to socket 2025.05.21 10:07:26 LOG7[0]: local_rfd/local_wfd reset (FD=3) 2025.05.21 10:07:26 LOG7[0]: Local descriptor (FD=3) closed 2025.05.21 10:07:26 LOG7[0]: Service [TLS SERVER] finished (0 left) The log for the successful case when "transparent = source is NOT specified in server config) instead says: 2025.05.21 09:59:58 LOG6[0]: s_connect: connecting ::1:7111 2025.05.21 09:59:58 LOG7[0]: s_connect: s_poll_wait ::1:7111: waiting 10 seconds 2025.05.21 09:59:58 LOG7[0]: FD=6 events=0x2001 revents=0x0 2025.05.21 09:59:58 LOG7[0]: FD=11 events=0x2005 revents=0x1 2025.05.21 09:59:58 LOG5[0]: s_connect: connected ::1:7111 2025.05.21 09:59:58 LOG6[0]: persistence: ::1:7111 cached 2025.05.21 09:59:58 LOG5[0]: Service [TLS SERVER] connected remote server from ::1:49806 2025.05.21 09:59:58 LOG7[0]: Setting remote socket options (FD=11) Any insight on what "Cannot assign an AF=2 address an AF=10 socket" is and how to fix it to preserve client IP address? stunnel is running as root, setuid is not used. I might not correctly understand the man page comment "This option is currently available in: Remote mode (connect option) on Linux >=2.6.28", but think it means a normal external connection request. Hopefully not a special configuration on the client side.

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SSL_CTX_load_verify_locations: Peer suddenly disconnected
by lynn9a＠yahoo.com 13 May '25

13 May '25

Hi, All When we try to start stunnel(stunnel 5.67, wolfSSL5.6.4 on linux), there is an error randomly happened like following, anybody knows why this happen and how to fix this? Thanks May 9 09:09:01 [ ] Initializing inetd mode configuration May 9 09:09:01 [ ] Clients allowed=500 May 9 09:09:01 [.] stunnel 5.67 on arm-oe-linux-gnueabi platform May 9 09:09:01 [.] Compiled/running with wolfSSL 5.6.4 May 9 09:09:01 [.] Threading:PTHREAD Sockets:POLL,IPv6,SYSTEMD TLS:OCSP,PSK,SNI May 9 09:09:01 [ ] errno: (*__errno_location ()) May 9 09:09:01 [ ] Initializing inetd mode configuration May 9 09:09:01 [.] Reading configuration from file /opt/config/stunnel.conf May 9 09:09:01 [.] UTF-8 byte order mark not detected May 9 09:09:01 [ ] No PRNG seeding was required May 9 09:09:01 [ ] Initializing service [xxxHost] May 9 09:09:01 [ ] stunnel default security level set: 2 May 9 09:09:01 [ ] Ciphers: TLS_AES_256_GCM_SHA384 May 9 09:09:01 [ ] TLSv1.3 ciphersuites: TLS_AES_256_GCM_SHA384:TLS_AES_128_GCM_SHA256:TLS_CHACHA20_POLY1305_SHA256 May 9 09:09:01 [ ] TLS options: 0x4D474C4C003000 (+0x0, -0x0) May 9 09:09:01 [ ] Session resumption enabled May 9 09:09:01 [ ] Loading certificate from file: ./config/client.pem May 9 09:09:01 [ ] Certificate loaded from file: ./config/client.pem May 9 09:09:01 [ ] Loading private key from file: ./config/client.key May 9 09:09:01 [:] Insecure file permissions on ./config/client.key May 9 09:09:01 [ ] Private key loaded from file: ./config/client.key May 9 09:09:01 [ ] Private key check succeeded May 9 09:09:01 [!] SSL_CTX_load_verify_locations: Peer suddenly disconnected May 9 09:09:01 [!] Service [xxxHost]: Failed to initialize TLS context May 9 09:09:01 [!] Configuration failed May 9 09:09:01 [ ] Deallocating temporary section defaults May 9 09:09:01 [ ] Deallocating section [xxxHost]

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Using intermediate CA as a trust anchor in stunnel
by Vít Holásek 30 Mar '25

30 Mar '25

Hi, I'm trying to setup stunnel to trust only certificates issued by intermediate CA and not other CAs issues by the same root CA. I came across this discussion about the same topic: https://www.stunnel.org/ mailman3/hyperkitty/list/stunnel-users(a)stunnel.org/thread/DUF6C6 BRNFVAWVCDIGXPUDTAPZR5KV5W/. I tested described options but it always authenticates also other sub CAs, because the whole chain must be always supplied in configured CAfile or CApath. In my opinion, the proper solution would be to add "partial chain" OpenSSL configuration option to stunnel config. This would allow admin to decide how intermediate CA will be verified. What do you think about that? See corresponding OpenSSL issue: https://github.com/openssl/openssl/issues/ 7871. Thanks Vit

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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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stunnel warning: SSL_accept: ../ssl/record/ssl3_record.c:354: error:0A00010B:SSL routines::wrong version number
by Marcel de Rooy 23 Jan '25

23 Jan '25

Hi, Taking this opportunity to ask a question on the mentioned warning. In our stunnel setup (stunnel server in a Docker container on Linux, version 5.68 and windows clients on version 5.73, no certificate verification) I am seeing every minute the following lines in stunnel.log on the server side: 2025.01.20 04:12:27 LOG5[0]: Service [siptest] accepted connection from 172.20.23.1:46658 2025.01.20 04:12:27 LOG3[0]: SSL_accept: ../ssl/record/ssl3_record.c:354: error:0A00010B:SSL routines::wrong version number 2025.01.20 04:12:27 LOG5[0]: Connection reset: 0 byte(s) sent to TLS, 0 byte(s) sent to socket This is every minute, so 04:13:27 again, etc. The warning is there already shortly after container restart without active connections to our SIP devices. I only see it recently. And changing the server/client config with sslVersionMin = TLSv1.2 and sslVersionMax = TLSv1.3 did not resolve it. Since it comes back every minute, I was thinking in the direction of keepalive settings. But do keep alives need encryption? Probably not. Is this just an innocent bug in the stunnel code or could I still do something in my configuration to clear the warn? Thank you for your attention. Marcel de Rooy Rijksmuseum Netherlands xxx

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How do I setup stunnel + openvpn for android (I already have the server running, I just need a android client, Sslsocks isn't working for some reason for me.)
by sharifkashif224＠gmail.com 23 Jan '25

23 Jan '25

I've tried using Sslsocks but it keeps giving me an error called unexpected eof while reading. This occurs when I try to initiate a connection via OpenVPN in android.

1 0

How do I use the android zip file provided in the download section in the stunnel website for android
by sharifkashif224＠gmail.com 22 Jan '25

22 Jan '25

I want to try connecting my openvpn server thats wrapped around stunnel onto my phone, any help will be appreciated!

1 0

Re: stunnel log file fills up with errors very fast
by Alan M Varghese (Nokia) 22 Jan '25

22 Jan '25

After digging into this a bit further, I was able to confirm that these "retries" are not created by stunnel itself. Rather, stunnel is simply trying to forward the connection attempts from NFS. Changing the NFS mount's "timeo" and "retrans" parameters affects duration for which NFS attempts to connect to the server. Thanks, Alan M Varghese

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stunnel log file fills up with errors very fast
by Alan M Varghese (Nokia) 19 Jan '25

19 Jan '25

Hello stunnel users, With stunnel (version: 5.71) setup and running (used to secure NFSv4 mounts), when the network interface is brought down, a huge number of messages are written to the log file (configured with the "output" option) in a very short amount of time. Below are some sample logs: 2025.01.19 14:19:58 LOG5[1044766]: Connection reset: 0 byte(s) sent to TLS, 0 byte(s) sent to socket 2025.01.19 14:19:58 LOG5[1044767]: Service [xxxxx] accepted connection from 127.0.0.1:994 2025.01.19 14:19:58 LOG3[1044767]: s_connect: connect 192.168.x.xx:xxxx: Network is unreachable (101) 2025.01.19 14:19:58 LOG3[1044767]: No more addresses to connect 2025.01.19 14:19:58 LOG5[1044767]: Connection reset: 0 byte(s) sent to TLS, 0 byte(s) sent to socket 2025.01.19 14:19:58 LOG5[1044768]: Service [xxxxx] accepted connection from 127.0.0.1:994 2025.01.19 14:19:58 LOG3[1044768]: s_connect: connect 192.168.x.xx:xxxx: Network is unreachable (101) 2025.01.19 14:19:58 LOG3[1044768]: No more addresses to connect ... This causes the log size to grow very quickly, sometimes overwhelming the filesystem. Log rotation alleviates this issue to some extent. But still, the archived logs would be filled with duplicate logs. This issue has been discussed by another user in the following thread: https://www.stunnel.org/mailman3/hyperkitty/list/stunnel-users@stunnel.org/… (Note, while the user in the thread above received "Connection refused" messages, here the error is "Network is unreachable". Otherwise, the behaviour with respect to logs is the same.) We would like to know if there is a way to control this connection behaviour from stunnel when "Network is unreachable" in such a manner. If not, is there a way to control/limit the log output from stunnel (without reducing the log level from default)? Steps to reproduce the issue: 1. Mount an NFSv4 filesystem using stunnel (configured to output logs to a file) 2. Bring down the network interfaces such that stunnel is not able to reach the configured server. (Please make sure to not lose access to the server while doing this.) 3. Wait ~300 seconds 4. Bring the interface(s) back up. 5. Examine the log size and contents. Thanks, Alan M Varghese

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Issue with OCSP messages in stunnel 5.73 and above
by Alexander Moisseev 02 Jan '25

02 Jan '25

Hello, I am experiencing an issue with stunnel versions 5.73 and above where the server logs are continuously filled with the following message: "OCSP: SSL_get_certificate" This issue does not occur in version 5.72. I am using PSK for encryption and have not configured OCSP. Here are the details of my setup: [.] stunnel 5.74 on amd64-portbld-freebsd14.1 platform [.] Compiled with OpenSSL 3.0.13 30 Jan 2024 [.] Running with OpenSSL 3.0.15 3 Sep 2024 - Server configuration file: ``` setuid = stunnel setgid = nogroup pid = /var/run/stunnel/stunnel.pid [bayes] accept = 6478 connect = 6378 ciphers = PSK PSKsecrets = /usr/local/etc/stunnel/psk.txt cert = /usr/local/etc/stunnel/cert.pem key = /usr/local/etc/stunnel/private.key [fuzzy] accept = 6477 connect = 6377 ciphers = PSK PSKsecrets = /usr/local/etc/stunnel/psk.txt cert = /usr/local/etc/stunnel/cert.pem key = /usr/local/etc/stunnel/private.key ``` - Client configuration file: ``` setuid = stunnel setgid = nogroup pid = /var/run/stunnel/stunnel.pid [bayes] client = yes accept = localhost:6478 connect = host.example.org:6478 ciphers = PSK PSKsecrets = /usr/local/etc/stunnel/psk.txt [fuzzy] client = yes accept = localhost:6477 connect = host.example.org:6477 ciphers = PSK PSKsecrets = /usr/local/etc/stunnel/psk.txt ``` - Relevant log entries: ``` Dec 27 09:00:10 mx stunnel[22113]: LOG3[per-minute]: OCSP: SSL_get_certificate ``` As a temporary workaround, I generated a self-signed certificate and configured stunnel to use it. This has resolved the issue with OCSP messages. However, I believe this is not the intended behavior when using PSK without configuring OCSP. I would appreciate any help or guidance on how to properly configure stunnel to avoid this issue without requiring a self-signed certificate. Thank you, Alexander

3 4

STUNNEL Installation to Windows Failover Cluster
by John Pipolo 19 Dec '24

19 Dec '24

Hi Is there any documentation or how to on installing STUNNEL to a 2 node Windows failover cluster? thx

1 0

[Bug][5.73] stunnel segfault and coredump due to OCSP handling
by stunnel＠benary.org 15 Dec '24

15 Dec '24

Hi everyone, I've recently upgraded from NixOS 24.05 to 24.11 which went from stunnel 5.72 to 5.73 and have since had stunnel crash on me multiple times on different servers (pretty much identical setup however) due to what looks like a memory allocation race? Since 5.73 moved OCSP fetches to a thread, and the problem hasn't ever happened with 5.72 it sounds like an issue specific to that. Someone familiar with the codebase probably has a better idea of what's going on. Given that my updates happened somewhen mid last month and there have been no certificate renewals since (except for one that wouldn't affect the systems that were affected, thanks so much to crt.sh and CT existing) the error message of "OCSP routines::status expired" also seems out of place at least for the certificate itself (the staple may be expired, but stunnel should probably get a new one in that case which may have to do with the error in question). ``` Dec 06 04:43:02 shell stunnel[1124111]: LOG5[per-minute]: OCSP: Certificate accepted Dec 06 04:43:02 shell stunnel[1124111]: 2024.12.06 04:43:02 LOG5[per-minute]: OCSP: Certificate accepted Dec 06 04:43:02 shell stunnel[1124111]: LOG5[per-minute]: OCSP: Certificate accepted Dec 06 04:43:02 shell stunnel[1124111]: 2024.12.06 04:43:02 LOG5[per-minute]: OCSP: Certificate accepted Dec 06 04:43:02 shell stunnel[1124111]: LOG5[per-minute]: OCSP: Certificate accepted Dec 06 04:43:02 shell stunnel[1124111]: 2024.12.06 04:43:02 LOG5[per-minute]: OCSP: Certificate accepted Dec 06 04:43:56 shell stunnel[1124111]: LOG5[ui]: Log file reopened Dec 06 04:43:56 shell stunnel[1124111]: 2024.12.06 04:43:56 LOG5[ui]: Log file reopened Dec 06 04:44:02 shell stunnel[1124111]: LOG3[per-minute]: OCSP: OCSP_check_validity: crypto/ocsp/ocsp_cl.c:351: error:1380007D:OCSP routines::status expired Dec 06 04:44:02 shell stunnel[1124111]: 2024.12.06 04:44:02 LOG3[per-minute]: OCSP: OCSP_check_validity: crypto/ocsp/ocsp_cl.c:351: error:1380007D:OCSP routines::status expired Dec 06 04:44:02 shell stunnel[1124111]: 2024.12.06 04:44:02 LOG4[per-minute]: OCSP: Unknown verification status Dec 06 04:44:02 shell stunnel[1124111]: INTERNAL ERROR: Memory allocated in a different thread at ocsp.c, line 412 Dec 06 04:44:02 shell stunnel[1124111]: LOG4[per-minute]: OCSP: Unknown verification status Dec 06 04:44:02 shell stunnel[1124111]: INTERNAL ERROR: Memory allocated in a different thread at ocsp.c, line 412 Dec 06 04:44:02 shell systemd-coredump[282485]: Process 1124111 (stunnel) of user 988 terminated abnormally with signal 6/ABRT, processing... Dec 06 04:44:02 shell systemd[1]: Started Process Core Dump (PID 282485/UID 0). Dec 06 04:44:02 shell systemd-coredump[282486]: [🡕] Process 1124111 (stunnel) of user 988 dumped core. Module libgcc_s.so.1 without build-id. Module libcap.so.2 without build-id. Module stunnel without build-id. Stack trace of thread 1124120: #0 0x00007f9191c99a9c __pthread_kill_implementation (libc.so.6 + 0x92a9c) #1 0x00007f9191c47576 raise (libc.so.6 + 0x40576) #2 0x00007f9191c2f935 abort (libc.so.6 + 0x28935) #3 0x000056142e23e435 fatal_debug.cold (stunnel + 0xc435) #4 0x000056142e23eebc get_alloc_list_ptr (stunnel + 0xcebc) #5 0x000056142e23f0b9 str_detach_debug.part.0 (stunnel + 0xd0b9) #6 0x000056142e23f856 str_free_debug (stunnel + 0xd856) #7 0x000056142e259635 ocsp_stapling (stunnel + 0x27635) #8 0x000056142e25a18f per_minute_thread (stunnel + 0x2818f) #9 0x00007f9191c97d02 start_thread (libc.so.6 + 0x90d02) #10 0x00007f9191d173ac __clone3 (libc.so.6 + 0x1103ac) Stack trace of thread 676245: #0 0x00007f9191d090af __poll (libc.so.6 + 0x1020af) #1 0x000056142e2509f1 s_poll_wait (stunnel + 0x1e9f1) #2 0x000056142e241f82 client_run (stunnel + 0xff82) #3 0x000056142e2438fc client_thread (stunnel + 0x118fc) #4 0x00007f9191c97d02 start_thread (libc.so.6 + 0x90d02) #5 0x00007f9191d173ac __clone3 (libc.so.6 + 0x1103ac) Stack trace of thread 1124111: #0 0x00007f9191d090af __poll (libc.so.6 + 0x1020af) #1 0x000056142e2509f1 s_poll_wait (stunnel + 0x1e9f1) #2 0x000056142e25b5f6 daemon_loop (stunnel + 0x295f6) #3 0x000056142e23e680 main (stunnel + 0xc680) #4 0x00007f9191c3127e __libc_start_call_main (libc.so.6 + 0x2a27e) #5 0x00007f9191c31339 __libc_start_main@@GLIBC_2.34 (libc.so.6 + 0x2a339) #6 0x000056142e23e875 _start (stunnel + 0xc875) Stack trace of thread 1124119: #0 0x00007f9191d090af __poll (libc.so.6 + 0x1020af) #1 0x000056142e2509f1 s_poll_wait (stunnel + 0x1e9f1) #2 0x000056142e250acd s_poll_sleep (stunnel + 0x1eacd) #3 0x000056142e25a21c per_second_thread (stunnel + 0x2821c) #4 0x00007f9191c97d02 start_thread (libc.so.6 + 0x90d02) #5 0x00007f9191d173ac __clone3 (libc.so.6 + 0x1103ac) Stack trace of thread 676190: #0 0x00007f9191d090af __poll (libc.so.6 + 0x1020af) #1 0x000056142e2509f1 s_poll_wait (stunnel + 0x1e9f1) #2 0x000056142e241f82 client_run (stunnel + 0xff82) #3 0x000056142e2438fc client_thread (stunnel + 0x118fc) #4 0x00007f9191c97d02 start_thread (libc.so.6 + 0x90d02) #5 0x00007f9191d173ac __clone3 (libc.so.6 + 0x1103ac) Stack trace of thread 1124121: #0 0x00007f9191d090af __poll (libc.so.6 + 0x1020af) #1 0x000056142e2509f1 s_poll_wait (stunnel + 0x1e9f1) #2 0x000056142e250acd s_poll_sleep (stunnel + 0x1eacd) #3 0x000056142e259fab per_day_thread (stunnel + 0x27fab) #4 0x00007f9191c97d02 start_thread (libc.so.6 + 0x90d02) #5 0x00007f9191d173ac __clone3 (libc.so.6 + 0x1103ac) Stack trace of thread 676445: #0 0x00007f9191d090af __poll (libc.so.6 + 0x1020af) #1 0x000056142e2509f1 s_poll_wait (stunnel + 0x1e9f1) #2 0x000056142e241f82 client_run (stunnel + 0xff82) #3 0x000056142e2438fc client_thread (stunnel + 0x118fc) #4 0x00007f9191c97d02 start_thread (libc.so.6 + 0x90d02) #5 0x00007f9191d173ac __clone3 (libc.so.6 + 0x1103ac) Stack trace of thread 676300: #0 0x00007f9191d090af __poll (libc.so.6 + 0x1020af) #1 0x000056142e2509f1 s_poll_wait (stunnel + 0x1e9f1) #2 0x000056142e241f82 client_run (stunnel + 0xff82) #3 0x000056142e2438fc client_thread (stunnel + 0x118fc) #4 0x00007f9191c97d02 start_thread (libc.so.6 + 0x90d02) #5 0x00007f9191d173ac __clone3 (libc.so.6 + 0x1103ac) Stack trace of thread 676491: #0 0x00007f9191d090af __poll (libc.so.6 + 0x1020af) #1 0x000056142e2509f1 s_poll_wait (stunnel + 0x1e9f1) #2 0x000056142e241f82 client_run (stunnel + 0xff82) #3 0x000056142e2438fc client_thread (stunnel + 0x118fc) #4 0x00007f9191c97d02 start_thread (libc.so.6 + 0x90d02) #5 0x00007f9191d173ac __clone3 (libc.so.6 + 0x1103ac) ELF object binary architecture: AMD x86-64 Dec 06 04:44:02 shell systemd[1]: stunnel.service: Main process exited, code=dumped, status=6/ABRT Dec 06 04:44:02 shell systemd[1]: stunnel.service: Failed with result 'core-dump'. Dec 06 04:44:02 shell systemd[1]: stunnel.service: Consumed 2min 11.812s CPU time, 21.6M memory peak, 19.6M memory swap peak, 50.9M read from disk, 47.1M written to disk, 587.2M incoming IP traffic, 588.8M outgoing IP traffic. ``` Note that stunnel is handling mTLS for my prometheus, which means that it is indeed getting hammered by one scrape per exporter at a time, which in this case would make exactly five scrapes per minute but all of them happening at the same time, which, if this is a race, does make me a lot more likely to hit this issue. Also a huge Thank You for building what has been an integral part of my infrastructure for almost a decade now.

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stunnel 5.74 released
by Michał Trojnara 13 Dec '24

13 Dec '24

Dear Users, I have released version 5.74 of stunnel. ### Version 5.74, 2024.12.13, urgency: HIGH * Bugfixes - Fixed a stapling cache deallocation crash. - Fixed "redirect" with protocol negotiation. * Features - "protocolHost" support for "socks" protocol clients. - More detailed logs in OpenSSL 3.0 or later. Home page: https://www.stunnel.org/ Download: https://www.stunnel.org/downloads.html SHA-256 hashes: 9bef235ab5d24a2a8dff6485dfd782ed235f4407e9bc8716deb383fc80cd6230 stunnel-5.74.tar.gz 8ce19cc782a64b0cacf32356249265ed16b3888e3578454853f5497726778d76 stunnel-5.74-win64-installer.exe 68c3395c1bebcc8b4eee2c7f58190aa2fe39b835dd7a4cce5ad37d5dfc1c5542 stunnel-5.74-android.zip Best regards, Mike

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Stunnel on a windwos 11 pro installation not working
by ron.reijgwart＠gmail.com 09 Dec '24

09 Dec '24

I'm trying to use Stunnel on a windwos 11 pro installation. I tried version 5.56, 5.73 and 5.74b1. On my old pc all was working fine but now I get the following errors: [ ] Initializing inetd mode configuration [ ] Running on Windows 6.2 [ ] No limit detected for the number of clients [.] stunnel 5.73 on x64-pc-mingw32-gnu platform [.] Compiled/running with OpenSSL 3.3.2 3 Sep 2024 [.] Threading:WIN32 Sockets:SELECT,IPv6 TLS:ENGINE,FIPS,OCSP,PSK,SNI [ ] errno: (*_errno()) [ ] Initializing inetd mode configuration [ ] Running on Windows 6.2 [.] Reading configuration from file C:\Program Files (x86)\stunnel\config\stunnel.conf [.] UTF-8 byte order mark detected [.] FIPS mode disabled [ ] Compression disabled [ ] No PRNG seeding was required [ ] Initializing service [ssmtp] [ ] Initializing context [ssmtp] [ ] OpenSSL security level is used: 2 [ ] Ciphers: HIGH:!aNULL:!SSLv2:!DH:!kDHEPSK [ ] TLSv1.3 ciphersuites: TLS_AES_256_GCM_SHA384:TLS_AES_128_GCM_SHA256:TLS_CHACHA20_POLY1305_SHA256 [ ] TLS options: 0x2100000 (+0x0, -0x0) [ ] Session resumption enabled [ ] Loading certificate from file: C:\Program Files (x64)\stunnel\config\stunnel.pem [!] error queue: ssl/ssl_rsa.c:472: error:0A080002:SSL routines::system lib [!] error queue: crypto/bio/bss_file.c:300: error:10080002:BIO routines::system lib [!] SSL_CTX_use_certificate_chain_file: crypto/bio/bss_file.c:297: error:80000003:system library::No such process [!] Service [ssmtp]: Failed to initialize TLS context [!] Configuration failed [ ] Deallocating temporary section defaults [ ] Cleaning up context [(null)] [ ] Deallocating section [ssmtp] [ ] Cleaning up context [ssmtp] On a windows 10 Education installation it works fine with this logging: 2024.12.05 13:38:58 LOG5[service]: Reading configuration from file C:\Program Files (x86)\stunnel\config\stunnel.conf 2024.12.05 13:38:58 LOG5[service]: UTF-8 byte order mark detected 2024.12.05 13:38:58 LOG5[service]: FIPS mode disabled 2024.12.05 13:38:58 LOG4[service]: Service [ssmtp] needs authentication to prevent MITM attacks 2024.12.05 13:38:58 LOG5[service]: Configuration successful My conf-file looks like this: ;use it for client mode client = yes [ssmtp] accept = 1925 cert = C:\Program Files (x64)\stunnel\config\stunnel.pem connect = smtp.bhosted.nl:465 Can you please give me some advice?

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Is it possible for stunnel to reject client connections if the server end cannot connect?
by mohmmad170720＠gmail.com 05 Dec '24

05 Dec '24

Hi all Say we have two machines set up, ClientPC and ServerPC. On ClientPC I run stunnel accepting a connection on a local port and connecting to an stunnel port on ServerPC. On ServerPC I run stunnel accepting a connection on the local stunnel port and connecting to the 'encryption unaware' server on another port on the same ServerPC machine. OK, pretty simple stuff so far. The problem is, when I connect to ClientPC with the 'encryption unaware' client app. then I always get a successful connection, even if there is no server running on ServerPC. Of course once the client has a successful connection, it then performs a write(), and that fails with 'Connection reset by peer'. Really, since there is no server running on ServerPC, I want the connect() to stunnel on ClientPC to fail. Is there a way to do this?

1 0

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?

1 0

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.

1 0

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.

2 1

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.

1 9

"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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