- stunnel-users - stunnel.org

Connection problems and TCP frame checksum errors
by Tommi Nieminen 23 Oct '06

23 Oct '06

I have the following kind of test environment: SSL clients call a public ip address from which the calls are forwarded to a linux server with Stunnel. The linux server is in a private network. Stunnel decrypts the data and sends it forward. I have been testing this with a browser, monitoring the traffic on the server to see that Stunnel forwards the calls. Some strange things happen there that I can't explain. First of all: sometimes the calls go through the server as expected, sometimes the server doesn't respond in any way to the client. If I have two terminal windows open, one with tcpdump and another with tail -f stunnel.log - nothing comes into the log in spite of the incoming connections attempts. Then on other occasions when the calls come to the server, it forwards them beautifully to the address and port set in the configuration file. Does anyone have any clue, what this could be due to? I haven't been able to explain why it sometimes works and sometimes doesn't. Another thing that bothers me is, that sometimes there are TCP frames with incorrect checksum. I've monitored with Ethereal and tcpdump. Both show incorrect frames, and they are always from the stunnel-end of the connection. What could be the cause of those broken frames? Tommi Nieminen -------------------------------------------------------- My stunnel.conf looks like this: (any constructive criticism would be welcome :-)) CAfile = /home/tommi/cert/7/demoCA/cacert.pem cert = /home/tommi/cert/7/newcert.pem key = /home/tommi/cert/7/newkey.pem socket = l:TCP_NODELAY=1 socket = r:TCP_NODELAY=1 output = /var/log/stunnel/stunnel.log pid = /var/run/stunnel/stunnel.pid debug = 7 client = no [https] accept = 443 connect = 192.168.10.17:5010 TIMEOUTclose = 0 -------------------------------------------------------- A succesful connection from stunnel.log: 2006.10.09 18:01:43 LOG7[11889:3083744960]: https accepted FD=7 from 131.177.254.92:2689 2006.10.09 18:01:43 LOG7[11889:3083742128]: https started 2006.10.09 18:01:43 LOG7[11889:3083742128]: FD 7 in non-blocking mode 2006.10.09 18:01:43 LOG7[11889:3083742128]: TCP_NODELAY option set on local socket 2006.10.09 18:01:43 LOG5[11889:3083742128]: https connected from 131.177.254.92:2689 2006.10.09 18:01:43 LOG7[11889:3083742128]: SSL state (accept): before/accept initialization 2006.10.09 18:01:43 LOG7[11889:3083742128]: SSL state (accept): SSLv3 read client hello A 2006.10.09 18:01:43 LOG7[11889:3083742128]: SSL state (accept): SSLv3 write server hello A 2006.10.09 18:01:43 LOG7[11889:3083742128]: SSL state (accept): SSLv3 write certificate A 2006.10.09 18:01:43 LOG7[11889:3083742128]: SSL state (accept): SSLv3 write server done A 2006.10.09 18:01:43 LOG7[11889:3083742128]: SSL state (accept): SSLv3 flush data 2006.10.09 18:01:43 LOG7[11889:3083742128]: SSL state (accept): SSLv3 read client key exchange A 2006.10.09 18:01:43 LOG7[11889:3083742128]: SSL state (accept): SSLv3 read finished A 2006.10.09 18:01:43 LOG7[11889:3083742128]: SSL state (accept): SSLv3 write change cipher spec A 2006.10.09 18:01:43 LOG7[11889:3083742128]: SSL state (accept): SSLv3 write finished A 2006.10.09 18:01:43 LOG7[11889:3083742128]: SSL state (accept): SSLv3 flush data 2006.10.09 18:01:43 LOG7[11889:3083742128]: 2 items in the session cache 2006.10.09 18:01:43 LOG7[11889:3083742128]: 0 client connects (SSL_connect()) 2006.10.09 18:01:43 LOG7[11889:3083742128]: 0 client connects that finished 2006.10.09 18:01:43 LOG7[11889:3083742128]: 0 client renegotiations requested 2006.10.09 18:01:43 LOG7[11889:3083742128]: 8 server connects (SSL_accept()) 2006.10.09 18:01:43 LOG7[11889:3083742128]: 7 server connects that finished 2006.10.09 18:01:43 LOG7[11889:3083742128]: 0 server renegotiations requested 2006.10.09 18:01:43 LOG7[11889:3083742128]: 4 session cache hits 2006.10.09 18:01:43 LOG7[11889:3083742128]: 1 session cache misses 2006.10.09 18:01:43 LOG7[11889:3083742128]: 1 session cache timeouts 2006.10.09 18:01:43 LOG6[11889:3083742128]: SSL accepted: new session negotiated 2006.10.09 18:01:43 LOG6[11889:3083742128]: Negotiated ciphers: AES256-SHA SSLv3 Kx=RSA Au=RSA Enc=AES(256) Mac=SHA1 2006.10.09 18:01:43 LOG7[11889:3083742128]: FD 8 in non-blocking mode 2006.10.09 18:01:43 LOG7[11889:3083742128]: https connecting 192.168.10.17:5010 2006.10.09 18:01:43 LOG7[11889:3083742128]: connect_wait: waiting 10 seconds 2006.10.09 18:01:43 LOG7[11889:3083742128]: connect_wait: connected 2006.10.09 18:01:43 LOG7[11889:3083742128]: Remote FD=8 initialized 2006.10.09 18:01:43 LOG7[11889:3083742128]: TCP_NODELAY option set on remote socket 2006.10.09 18:02:45 LOG7[11889:3083742128]: Socket closed on read 2006.10.09 18:02:45 LOG7[11889:3083742128]: SSL write shutdown 2006.10.09 18:02:45 LOG7[11889:3083742128]: SSL alert (write): warning: close notify 2006.10.09 18:02:45 LOG7[11889:3083742128]: SSL_shutdown retrying 2006.10.09 18:02:45 LOG7[11889:3083742128]: SSL doesn't need to read or write 2006.10.09 18:02:45 LOG6[11889:3083742128]: s_poll_wait timeout: connection close 2006.10.09 18:02:45 LOG5[11889:3083742128]: Connection closed: 0 bytes sent to SSL, 405 bytes sent to socket 2006.10.09 18:02:45 LOG7[11889:3083742128]: https finished (0 left) (and the failed connections leave also no mark in the log, but tcpdump sees the attempts on the server) -------------------------------------------------------- A sample of tcpdump's output with incorrect checksum: 18:02:45.150656 IP (tos 0x0, ttl 64, id 11218, offset 0, flags [DF], proto: TCP (6), length: 77) 192.168.20.18.https > 131.177.254.92.2689: P, cksum 0x5708 (incorrect (-> 0xf1bf), 1035:1072(37) ack 756 win 7504

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Thank you very much for all your donations
by Michal Trojnara 21 Oct '06

21 Oct '06

Dear Users, I want you to know how much grateful I am for all your donations. Thank you very much. Some day stunnel may be full-time job. 8-) Even now sponsored features make a substantial addition to my budget. BTW: I have updated currency to USD. I hope it's more convenient. http://stunnel.mirt.net/ Best regards, Mike

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error 1703, service already exists.
by Joop Blokker 20 Oct '06

20 Oct '06

Hello, I'm using sTunnel v4.18 under Windows XP as a client. I start the serv= ice with sTunnel -install -quiet If, for any reason, the same command is given again then the error mes= sage "Create service; error 1703; the specified service already exists= " pops up. In that case the -quiet parameter does not work. I do not w= ant to see that error message; if the service is running then it's oka= y. Q:. How can I suppress that error message? If that is not an option, h= ow can I detect that the sTunnel service is installed already? I'm programming in PowerBASIC - I know how to detect sTunnel once it h= as started with -start -quiet Thanks in advance for any idea! Joop. +++ Too far East is West. - Proverb (English) +++

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stunnel client without any configuration
by Thomas Stegbauer 18 Oct '06

18 Oct '06

hi ml, i searched the list about an idea, but didn't find the complete answer, so i would ask: i am thinking about a https website (with logon), where you can download a completly preconfigured package (java-applet?) which checks HTTP_PROXY on unix and the msie registry settings on windows and connect a local port to a remote running stunnel, listening on port 443 (the stunnel ist running on a different ip). currently there are imho two points, which need solved: 1.) there is no proxy support, without a patch 2.) it is currently not possible to download a preconfigured package are there some thoughts? greetings thomas -- # Thomas Stegbauer # https://keyserver1.pgp.com/vkd/DownloadKey.event?keyid=0x9A3F1866FC68E91D # Key fingerprint = 5A2D FEDC 8A50 F1BB 25FB 967B 9A3F 1866 FC68 E91D

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Infinite client timeout
by Dario Mariani 18 Oct '06

18 Oct '06

Hi all, i'm a new user :) I'm deploying stunnel into a big enterprise, so i have met a lot of interesting details about Stunnel :) I have a little problem now: a Stunnel channel connecting BEA Weblogic -> Oracle listener. BEA has the BIG problem of _completely locking_ when the connection goes down: when the connection comes up again, bea doesn't work. This is not an issue, because there's a keepalive feature that can be activated in BEA. In a case, we _cannot_ activate the keepalive, so we must try to keep the BEA -> stunnel client conection open indefinitely. I think this must apply to the other parts of the connection, but i'm not sure (if the bea -> client connection remains active, the client then can renegotiate the connection without bea noticing it? and the server -> oracle connection?) Ok, i'm a little confused here :) Can you help me with this issue? Bye, dario.

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New feature - PayPal donations
by Michal Trojnara 16 Oct '06

16 Oct '06

Dear Users, Since PayPal finally decided to provide full support for users in Poland I've added a donation button on the web page. http://stunnel.mirt.net/ I really appreciate each donation. 8-) Best regards, Mike

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"Peer suddenly disconnected" after upgrade to 4.18
by Asarian 13 Oct '06

13 Oct '06

Hello, I'm a long time user of stunnel. Yesterday I finally upgraded to stunnel 4.18. Can't get it to work anymore, though. :( Here is the relevant part of my config: ----------------------- cert = /etc/stunnel.pem key = /etc/stunnel.pem ciphers = ALL:!ADH:RC4+RSA:+SSLv2:@STRENGTH sslVersion = SSLv2 setuid = nobody setgid = nobody socket = l:TCP_NODELAY=1 debug = 5 pid = /var/run/stunnel.pid RNDbytes = 64 RNDfile = /dev/urandom RNDoverwrite = yes session = 300 seconds verify = none [pop3s] accept = 995 exec = /usr/local/libexec/inet-qpopper execargs = inet-qpopper -s transparent = yes [imaps] accept = 993 exec = /usr/local/libexec/imapd execargs = imapd transparent = yes ----------------------- With the exception of a few keyword changes, this is the config I've always used. But I always get these errors now: Oct 14 00:57:40 asarian-host stunnel: LOG5[49682:134621184]: pop3s connected from 192.168.79.4:2576 Oct 14 00:57:40 asarian-host stunnel: LOG3[49682:134621184]: SSL_accept: Peer suddenly disconnected Oct 14 00:57:40 asarian-host stunnel: LOG3[49682:134621184]: SSL_accept: Peer suddenly disconnected Oct 14 00:57:40 asarian-host stunnel: LOG5[49682:134621184]: Connection reset: 0 bytes sent to SSL, 0 bytes sent to socket Oct 14 00:57:40 asarian-host stunnel: LOG5[49682:134621184]: pop3s connected from 192.168.1.4:2579 Oct 14 00:57:40 asarian-host stunnel: LOG3[49682:134621184]: SSL_accept: Peer suddenly disconnected Oct 14 00:57:40 asarian-host stunnel: LOG5[49682:134621184]: Connection reset: 0 bytes sent to SSL, 0 bytes sent to socket The cert and key are good (I use em for Apache, too). I also tried SSLv3, but got this error: error:1408F10B:SSL routines:SSL3_GET_RECORD:wrong version number But I like to get it working with SSLv2 first; then I'll worry about the other thing later. :) I hope someone can tell me what I'm doing wrong. Thanks, - Mark

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SegFault with stunnel
by Beyerle, Christian 12 Oct '06

12 Oct '06

Hello Everyone, I try to encrypt a Mysql-Connection between two host which run Suse Linux 10.1. On the Server runs a mysql database, on the client runs barnyard (a plugin for snort) which should write into the mysql database. I installed stunnel 4.14 on x86_64-suse-linux-gnu UCONTEXT+POLL+IPv4+LIBWRAP with OpenSSL 0.9.8a 11 Oct 2005 on both servers. The Configuration file on the Server (mysql) looks like: client = no debug = 7777777 output = /var/log/stunnel.log [mysqls] accept = 10439 connect = 127.0.0.1:3306 Stunnel seems to run well: lsof -i -n | grep stunnel stunnel 25330 stunnel 6u IPv4 371490 TCP *:10439 (LISTEN) On the client: [mysqls] client = yes accept = 127.0.0.1:3306 connect = 172.16.1.80:10439 Stunnel seems to run as well as on the server: stunnel 16634 stunnel 6u IPv4 22487 TCP 127.0.0.1:mysql (LISTEN) If i start barnyard that should connect to port 3306, barnyard cannot open the port and quits. I looked in my syslog and found the following entry: Oct 12 14:10:28 CLIENT kernel: stunnel[10991]: segfault at 0000000055697fb0 rip 000055555555b793 rsp 00005555556b0520 error 4 Oct 12 14:10:28 CLIENT barnyard[10997]: FATAL ERROR: Failed to connect to database snort:[email protected]/sensors: Lost connection to MySQL server during query Oct 12 14:10:28 CLIENT barnyard[10997]: Exiting I find no log of stunnel which help me to understand the reason of the crash. After this stunnel not too seem runnign anymore on the port: lsof -i -n | grep stunnel (no output) Does anybody have an idea??? Thank you for the help, -- Chris

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[stunnel-users]Plan for new authorisation method in Stunnel
by Thomas Thiele 11 Oct '06

11 Oct '06

Hello Stunnel Users, I am planning to develop a new authorisation method for Stunnel which I need for work. This method will be an addition to the existing methods for checking certificates. The idea is to use the subject names and the alternative names of the certificates to allow or drop connections. The subject and alternative names of the machines/clients that are allowed to connect to the server will be written into the Stunnel config. While checking the certificates, the subject and alternative names from the Stunnel config will be compared with the subject and alternative names in the certirficate from the connection request. If one of the names from the Stunnel config matches with the names from the certificate then the connection will be allowed. This is the basic idea of my project. Is anyone already working on something like that or do you have any ideas or suggestions for me? Best Regards, Thomas Thiele -- GMX DSL-Flatrate 0,- Euro* - Überall, wo DSL verfügbar ist! NEU: Jetzt bis zu 16.000 kBit/s! http://www.gmx.net/de/go/dsl

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libstunnel.so
by Andrew Schulman 05 Oct '06

05 Oct '06

The Debian stunnel (actually stunnel4) package includes /usr/lib/libstunnel.so. I have two questions about this file: (1) What is its purpose? ldd shows that /usr/bin/stunnel doesn't depend on it. So is this the shared library referred to in stunnel(1), under the 'transparent' option? The man page says that to use 'transparent' one has to LD_PRELOAD env.so, but I don't find any env.so. I see that env.c is used in building libstunnel.a, so I'm guessing that the man page meant to say libstunnel.so instead of env.so. (2) How does one build it? configure includes a --with-shared-libs option, but even when that's enabled I don't get a libstunnel.so when I build. And I can't find any make targets for any .so files. Yet Debian includes this file. Thanks, Andrew.

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