June 2018 - stunnel-users

stunnel used as jump host for SFTP
by Schultz, Cecilia 20 Jun '18

20 Jun '18

Hello, I am trying to test stunnel to see if it can provide the functionality we need. We are a Windows shop. What we need is for multiple client machines (I call these C1, C2, C3) to connect to our server (S). Server S will connect to a remote SFTP server (port 22). I call the remote SFTP server "R". C1, C2, C3 and S are all inside our firewall. Currently S can connect and send files to R using SFTP (port 22). The problem is that R does not accept a range of IP addresses, and has a limit on the number of IP addresses they can accept. So, what I need is for C1, C2, C3 to be able to connect to server R using S as a jump host. >From R's perspective, it should be like the connection is coming from S. Question 1: can stunnel be used to accomplish this? Question 2: I have installed stunnel in a test server ("stunnel -install" actually from the bin folder), and configured the conf like this: [sftp] accept=127.0.0.1:22 connect=some.remote.server.com:22 I tried to use Winscp SFTP client to test a connection, but it times out. I then checked S, and I don't see anything listening on port 22. I did "netstat -a" and I don't see anything listening on port 22. Was something wrong in the "stunnel -install" command? Shouldn't it be listening on port 22? Also, I uncommented the entry for log, but I don't see any log file in the stunnel folder/subfolders ; Debugging stuff (may be useful for troubleshooting) debug = info output = stunnel.log Thanks for your help, Cecilia

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Re: [stunnel-users] stunnel used as jump host for SFTP
by Schultz, Cecilia 20 Jun '18

20 Jun '18

Thank you so much for the info! I will try this out. From: stunnel-users <stunnel-users-bounces(a)stunnel.org> On Behalf Of Harris, Douglas (SSC/SPC) Sent: Wednesday, June 20, 2018 5:08 AM To: stunnel-users(a)stunnel.org Subject: Re: [stunnel-users] stunnel used as jump host for SFTP You can accomplish this in Windows. Just add a port forwarding rule to S: netsh interface portproxy add v4tov4 listenport=22 listenaddress=[IP of S] connectport=22 connectaddress=[IP of R] -Doug

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stunnel PSK support via custome openssl engine
by Tarakeshwar Rao 14 Jun '18

14 Jun '18

Dear Stunnel-users, >From Stunnel man pages, I could see that we could read PSK secret from plain text file with following option: PSKsecrets = psk.txt Could it possible to use custom openssl engine to read PSK file from HSM. I know that this works for reading TLS keys. I am not sure how I could do it for PSK. Thanks for your support, Regards, Tarak

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is it possible to make stunnel works for dbmail timsieved?
by cktmwe＠gmail.com 11 Jun '18

11 Jun '18

hello everyone, I'm currently try to stunnel sieve traffic to local dbmail timsieved, unfortunately I couldn't get it to work, my first question, does stunnel support sieve manage protocol? secondly if it does, how can I config the service? what I've done so far. timsieved started on 127.0.0.1:2000, connect and manage all works, I saw connection in dbmail log, then define sieve service block in stunnel.conf, restart stunnel, but if I connect our.public.ip:4190, timsieved becames no connection at all, dbmail log kept silent. traffic from port 4190 is already accepted in iptables. config that I used. > [sieve] > accept = our.public.ip:4190 > connect = 127.0.0.1:2000 > software version: stunnel-5.43 dbmail-3.2.3 Thanks.

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Slow DNS lookups when DNS does not respond
by Guillermo Rodriguez Garcia 08 Jun '18

08 Jun '18

Hi all, I have stunnel setup on a Linux box and I am experiencing very slow DNS lookup times when DNS does not respond. On this same system, anything that results in a DNS lookup (e.g. ping, ...) takes about 20 seconds before it times out and fails. However with stunnel (and a single service configured) the lookup takes more than 1 minute (approx 80 seconds). Is there any way to configure this? Thank you, Guillermo Rodriguez Garcia guille.rodriguez(a)gmail.com

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Windows 2016 Server: [!] bind: Address already in use (WSAEADDRINUSE) (10048)
by Martin Schweizer 05 Jun '18

05 Jun '18

Hello List My problem: If I run stunnel I regular get the below error: [.] stunnel 5.46 on x86-pc-msvc-1500 platform [.] Compiled/running with OpenSSL 1.0.2o-fips 27 Mar 2018 [.] Threading:WIN32 Sockets:SELECT,IPv6 TLS:ENGINE,FIPS,OCSP,PSK,SNI [ ] errno: (*_errno()) [ ] Running on Windows 6.2 [.] Reading configuration from file stunnel.conf [.] UTF-8 byte order mark detected [.] FIPS mode disabled [ ] Compression disabled [ ] No PRNG seeding was required [ ] Initializing service [smtps] [ ] GUI message loop initialized [ ] Ciphers: HIGH:!aNULL:!SSLv2:!DH:!kDHEPSK [ ] TLS options: 0x03000004 (+0x00000000, -0x00000000) [ ] Loading certificate from file: stunnel.pem [ ] Certificate loaded from file: stunnel.pem [ ] Loading private key from file: stunnel.pem [ ] Private key loaded from file: stunnel.pem [ ] Private key check succeeded [:] Service [smtps] needs authentication to prevent MITM attacks [.] Configuration successful [ ] Binding service [smtps] [ ] Listening file descriptor created (FD=676) [ ] Setting accept socket options (FD=676) [ ] Option SO_EXCLUSIVEADDRUSE set on accept socket >>> [!] bind: Address already in use (WSAEADDRINUSE) (10048) <<<< [!] Error binding service [smtps] to 192.168.10.62:11465 [!] Could not bind any accepting port [ ] Deallocating section defaults [ ] Unbinding service [smtps] [ ] Service [smtps] closed [ ] Deallocating section [smtps] I had the same problem with the previous versions aswell. To temporary resolv the problem I have to change the listen port to another number. Reread the config file and let the stunnel GUI open. Then all is working until I close the GUI (not each time but most of). My system: - Windows 2016 Server - stunnel-5.46 - stunnel installed as service and GUI My config file (relevant part): taskbar = yes client=yes [smtps] ;delay = yes accept = 192.168.10.62:11466 connect = server.domain.ch:465 cert = stunnel.pem local = 192.168.10.53 (this is dedicated address) I found a similar threat in the archives (but on Linux): https://www.stunnel.org/pipermail/stunnel-users/2018-February/005935.html Here is Microsoft's describtion about WSAEADDRINUSE) (10048): https://msdn.microsoft.com/en-us/library/windows/desktop/ms740668(v=vs.85).… All helps are welcome. Kind regards, -- Martin Schweizer PC-Service M. Schweizer GmbH; Bannholzstrasse 6; Postfach 132; CH-8608 Bubikon; Tel. +41 55 243 30 00; Fax: +41 55 243 33 22

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