August 2010 - stunnel-users

Is it possible for stunnel to reject client connections if the server end cannot connect?
by Martin van den Nieuwelaar 27 Aug '10

27 Aug '10

Hi all. I took a look (manually) through the last year of archives, but didn't find anything on this issue. The situation is as follows. 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? The alternative (which is a kludge), is to make the client 'stunnel aware' (yuk!), and to tell it whether it's connecting over stunnel on a per connection basis (yuk!). Then it can know whether it needs to look at the connect() or the write() to know whether the server is not running. Yuk! Or am I overlooking something simple? :-) -- R A Ward Ltd. | We take the privacy of our customers seriously. Christchurch | All sensitive E-Mail attachments MUST be encrypted. New Zealand

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Problem with 2048 bits SSL sertificate with stunnel
by Georgi Georgiev 23 Aug '10

23 Aug '10

Hello to all, We get 2048 bits wildcard certificate for our domain *.domain.com .. And we are using thawte as Certificate Authority . So they send as two certificates .. One for SSL web and one intermediate certificate .. The stunnel configuration is : [https1] cert = /etc/stunnel/domain.crt CAfile = /etc/stunnel/domain.intermediate.crt key = /etc/stunnel/domain.key.nopass verify = 0 accept = x.x.x.x:443 connect = x.x.x.x:81 xforwardedfor=yes even I use verify = 0 some of our clients still complains that on some pages ( like blabla.domain.com ) server wants some of their private certificate to be send to the server !! and it's happens only with Internet Explorer 8.0 without verify and CAfile commands IE 8.0 works fine but Mozilla Firefox claim that can find CA be trusted ! wildcard certificate cannot be reissued with 1024 bits key . So is there some mistake in my configuration ? If not what can I do about it ? Thanks in advance .. P.S.: version of stunnel is 4.20 with XForwardedFor patch ..

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stunnel and loading keys from hw devices
by Victor Wagner 20 Aug '10

20 Aug '10

Hello, all I've tried to use stunnel with keys on the hardware device, supported by OpenSSL engine and encountered some minor problems: 1. Under Unix systems stunnel doesn't provide UI_METHOD for ENGINE_load_private_key. It passes NULL there and engine complains that no user interface provided. On Unix in many cases default UI_METHOD provided by OpenSSL would do So, replacing line 302 in the ctx.c (line number are given for release 4.33) from uim=NULL ; to uim=UI_OpenSSL(); would significanly improve stunnel functionality. 2. OpenSSL UI objects have two methods to pass arbitraty pointers along 1. generic ex_data based macros UI_set_app_data/UI_get_app_data 2. UI-specific UI_add_user_data/UI_get0_user_data Unfortunately app-specific pointer is set inside engine and retrieved inside a callback, which belongs to application. So author of an engine and author of an application should somehow agree on which metod to use. All engines shipped with OpenSSL (ones which do provide load_private_key method) use UI_add_user_data to pass data to the callback. stunnel's pin_cb (for Win32 version of stunnel in the gui.c) uses UI_get_app_data to retrieve ui_data. I wonder what engine was used when this code was developed and debugged. And it does no check if any meaningful pointer is obtained. I suggest to add following code after line 602 in gui.c: /* if set_app_Data haven't-return anything */ if (!ui_data) ui_data=UI_get0_user_data(ui); /* if still no avail */ if (!ui_data) { s_log(LOG_ERR,"Engine haven't passed our callback data to callback. Sorry!"); return 0; } Or instead of complaining we can use some structure, local to function pin_cb as fallback UI_DATA - just as password buffer, and check if ui_data->section is not NULL before reading ui_data->section->key in the pass_proc (line 543 of gui.c) Thus it would work even with really broken engines which do not pass userdata from ENGINE_load_private_key to UI callbacks at all. ----- End forwarded message -----

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stunnel and mod_gnutls
by Yclept Nemo 15 Aug '10

15 Aug '10

I run a mod_gnutls (0.5.5)<->apache (2.2.8) webserver which behaves perfectly normally outside of stunnel: GnuTLSEnable on GnuTLSPriorities SECURE256 GnuTLSExportCertificates on .. When a connection is closed and apache signals the mod_gnutls process to quit, the log records: GnuTLS: Handshake Failed (-8) 'A record packet with illegal version was received.' Invalid method in request NS * HTTP/1.0 ::1 - - [15/Aug/2010:03:31:26 -0400] "NS * HTTP/1.0" 501 512 "-" "Apache/2.2.8 (Ubuntu) ... (internal dummy connection)" This lets me easily identify apache2 process turnovers However, when I connect to this server through stunnel, I receive random dropouts. For example, if I were to upload 200 test files to this server, on average 15 transfers would fail. Stunnel logs (excerpt): 2010.08.15 04:11:25 LOG5[29287:3074030448]: Connection reset: 94 bytes sent to SSL, 523 bytes sent to socket 2010.08.15 04:12:21 LOG5[29287:3074448240]: Connection reset: 94 bytes sent to SSL, 523 bytes sent to socket 2010.08.15 04:12:34 LOG5[29287:3074030448]: Connection reset: 94 bytes sent to SSL, 523 bytes sent to socket And my apache2 logs are flooded with: Invalid method in request \x16\x03\x01 # ... over and over and over ... Invalid method in request \x16\x03\x01 # ... this is a tls hello sequence, as though the webserver were not running mod_gnutls ::1 - - [15/Aug/2010:03:31:26 -0400] "NS * HTTP/1.0" 501 512 "-" "Apache/2.2.8 (Ubuntu) ... (internal dummy connection)" The apache logs show new apache2 processes / new ssl connections being created every 2-5 seconds. A normal connections lasts much longer. stunnel configuration debug=7 foreground=yes client=yes syslog=no pid=/absolute/path/to/stunnel.pid libwrap=no [https] accept=127.0.0.1:11111 connect=my.website.net:myport sslVersion=TLSv1 an excerpt from the stunnel log: 2010.08.15 04:11:25 LOG6[29287:3074030448]: SSL connected: previous session reused 2010.08.15 04:11:25 LOG7[29287:3073960816]: Service https started 2010.08.15 04:11:25 LOG7[29287:3073960816]: FD=19 in non-blocking mode 2010.08.15 04:11:25 LOG5[29287:3073960816]: Service https accepted connection from 127.0.0.1:52674 2010.08.15 04:11:25 LOG7[29287:3073960816]: FD=20 in non-blocking mode 2010.08.15 04:11:25 LOG6[29287:3073960816]: connect_blocking: connecting 44.205.51.83:12389 2010.08.15 04:11:25 LOG7[29287:3073960816]: connect_blocking: s_poll_wait 44.205.51.83:12389: waiting 10 seconds 2010.08.15 04:11:25 LOG5[29287:3073960816]: connect_blocking: connected 44.205.51.83:12389 2010.08.15 04:11:25 LOG5[29287:3073960816]: Service https connected remote server from 192.168.1.8:51590 2010.08.15 04:11:25 LOG7[29287:3073960816]: Remote FD=20 initialized 2010.08.15 04:11:25 LOG7[29287:3073960816]: SSL state (connect): before/connect initialization 2010.08.15 04:11:25 LOG7[29287:3073960816]: SSL state (connect): SSLv3 write client hello A 2010.08.15 04:11:25 LOG7[29287:3073960816]: SSL state (connect): SSLv3 read server hello A 2010.08.15 04:11:25 LOG7[29287:3073960816]: SSL state (connect): SSLv3 read finished A 2010.08.15 04:11:25 LOG7[29287:3073960816]: SSL state (connect): SSLv3 write change cipher spec A 2010.08.15 04:11:25 LOG7[29287:3073960816]: SSL state (connect): SSLv3 write finished A 2010.08.15 04:11:25 LOG7[29287:3073960816]: SSL state (connect): SSLv3 flush data 2010.08.15 04:11:25 LOG7[29287:3073960816]: 1 items in the session cache 2010.08.15 04:11:25 LOG7[29287:3073960816]: 42 client connects (SSL_connect()) 2010.08.15 04:11:25 LOG7[29287:3073960816]: 42 client connects that finished 2010.08.15 04:11:25 LOG7[29287:3073960816]: 0 client renegotiations requested 2010.08.15 04:11:25 LOG7[29287:3073960816]: 0 server connects (SSL_accept()) 2010.08.15 04:11:25 LOG7[29287:3073960816]: 0 server connects that finished 2010.08.15 04:11:25 LOG7[29287:3073960816]: 0 server renegotiations requested 2010.08.15 04:11:25 LOG7[29287:3073960816]: 41 session cache hits 2010.08.15 04:11:25 LOG7[29287:3073960816]: 0 external session cache hits 2010.08.15 04:11:25 LOG7[29287:3073960816]: 0 session cache misses 2010.08.15 04:11:25 LOG7[29287:3073960816]: 0 session cache timeouts 2010.08.15 04:11:25 LOG6[29287:3073960816]: SSL connected: previous session reused 2010.08.15 04:11:25 LOG3[29287:3074030448]: SSL socket closed on SSL_read with 7 byte(s) in buffer 2010.08.15 04:11:25 LOG5[29287:3074030448]: Connection reset: 94 bytes sent to SSL, 523 bytes sent to socket 2010.08.15 04:11:25 LOG7[29287:3074030448]: Service https finished (4 left) 2010.08.15 04:11:25 LOG7[29287:3073960816]: SSL socket closed on SSL_read 2010.08.15 04:11:25 LOG7[29287:3073960816]: Socket write shutdown 2010.08.15 04:11:25 LOG5[29287:3073960816]: Connection closed: 94 bytes sent to SSL, 523 bytes sent to socket 2010.08.15 04:11:25 LOG7[29287:3073960816]: Service https finished (3 left) 2010.08.15 04:11:26 LOG7[29287:3074448240]: SSL socket closed on SSL_read 2010.08.15 04:11:26 LOG7[29287:3074448240]: Socket write shutdown 2010.08.15 04:11:26 LOG5[29287:3074448240]: Connection closed: 1110 bytes sent to SSL, 77962 bytes sent to socket 2010.08.15 04:11:26 LOG7[29287:3074517872]: SSL socket closed on SSL_read 2010.08.15 04:11:26 LOG7[29287:3074517872]: Socket write shutdown 2010.08.15 04:11:26 LOG7[29287:3074448240]: Service https finished (2 left) 2010.08.15 04:11:26 LOG5[29287:3074517872]: Connection closed: 575 bytes sent to SSL, 4889 bytes sent to socket 2010.08.15 04:11:26 LOG7[29287:3074517872]: Service https finished (1 left) 2010.08.15 04:11:26 LOG7[29287:3074378608]: SSL socket closed on SSL_read 2010.08.15 04:11:26 LOG7[29287:3074378608]: Socket write shutdown 2010.08.15 04:11:26 LOG5[29287:3074378608]: Connection closed: 573 bytes sent to SSL, 48787 bytes sent to socket 2010.08.15 04:11:26 LOG7[29287:3074378608]: Service https finished (0 left) 2010.08.15 04:11:26 LOG7[29287:3074520768]: Service https accepted FD=11 from 127.0.0.1:52676 2010.08.15 04:11:26 LOG7[29287:3074378608]: Service https started 2010.08.15 04:11:26 LOG7[29287:3074378608]: FD=11 in non-blocking mode 2010.08.15 04:11:26 LOG5[29287:3074378608]: Service https accepted connection from 127.0.0.1:52676 2010.08.15 04:11:26 LOG7[29287:3074378608]: FD=12 in non-blocking mode 2010.08.15 04:11:26 LOG6[29287:3074378608]: connect_blocking: connecting 44.205.51.83:12389 2010.08.15 04:11:26 LOG7[29287:3074378608]: connect_blocking: s_poll_wait 44.205.51.83:12389: waiting 10 seconds 2010.08.15 04:11:26 LOG5[29287:3074378608]: connect_blocking: connected 44.205.51.83:12389 2010.08.15 04:11:26 LOG5[29287:3074378608]: Service https connected remote server from 192.168.1.8:51592 2010.08.15 04:11:26 LOG7[29287:3074378608]: Remote FD=12 initialized 2010.08.15 04:11:26 LOG7[29287:3074378608]: SSL state (connect): before/connect initialization 2010.08.15 04:11:26 LOG7[29287:3074378608]: SSL state (connect): SSLv3 write client hello A 2010.08.15 04:11:26 LOG7[29287:3074378608]: SSL state (connect): SSLv3 read server hello A 2010.08.15 04:11:26 LOG7[29287:3074378608]: SSL state (connect): SSLv3 read finished A 2010.08.15 04:11:26 LOG7[29287:3074378608]: SSL state (connect): SSLv3 write change cipher spec A 2010.08.15 04:11:26 LOG7[29287:3074378608]: SSL state (connect): SSLv3 write finished A 2010.08.15 04:11:26 LOG7[29287:3074378608]: SSL state (connect): SSLv3 flush data My questions are: Why does this happen (why only with stunnel), and how can I prevent/avoid this? Sincerely,

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