Hello,

have anyone experienced a issue with stunnel when there's a larger number of concurrent connections (>50)?

I've got my application service and stress tester for it. I've placed stunnel in front of application service because I allow clients only to connect to application service using SSL. When stress tester communicates directly with application service with 100 concurrent connections (threads) there's no issue, but when I connect over SSL (thru stunnel) more than 50% of connections fails with error : connection refused :(

Seems like there's a limit in windows server for number of threads per process since stunnel does one thread per connection, right?

Any idea on how can I test this further?

stunnel information: stunnel 4.22 on x86-pc-mingw32-gnu with OpenSSL 0.9.8g 19 Oct 2007 Threading:WIN32 SSL:ENGINE Sockets:SELECT,IPv6

Global options debug = 5 RNDbytes = 64 RNDoverwrite = yes service = stunnel taskbar = yes

Service-level options cert = stunnel.pem ciphers = AES:ALL:!aNULL:!eNULL:+RC4:@STRENGTH key = stunnel.pem session = 300 seconds stack = 65536 bytes sslVersion = SSLv3 for client, all for server TIMEOUTbusy = 300 seconds TIMEOUTclose = 60 seconds TIMEOUTconnect = 10 seconds TIMEOUTidle = 43200 seconds verify = none

Socket option defaults: Option Accept Local Remote OS default SO_DEBUG -- -- -- 0 SO_DONTROUTE -- -- -- 0 SO_KEEPALIVE -- -- -- 0 SO_LINGER -- -- -- 0:0 SO_OOBINLINE -- -- -- 0 SO_RCVBUF -- -- -- 8192 SO_SNDBUF -- -- -- 8192 SO_RCVLOWAT -- -- -- -- SO_SNDLOWAT -- -- -- -- SO_RCVTIMEO -- -- -- 0:0 SO_SNDTIMEO -- -- -- 0:0 SO_REUSEADDR 1 -- -- 0 IP_TOS -- -- -- 0 IP_TTL -- -- -- 32 TCP_NODELAY -- -- -- 0

Software configuration: Windows Server 2003 R2 - Enterprise x64 Edition

Hardware configuration: Intel Core 2 Duo 1 GB RAM

Kind regards, fritz