[stunnel-users] FD_SETSIZE still an option in stunnel 4.34?

Saikat Chakrabarti saikat at gomockingbird.com
Tue Nov 2 18:35:35 CET 2010


I am having some issues with my server where connections are getting
dropped once I hit a hard limit of around 350 connections.  This may
or may not be an issue with my stunnel configuration, but I ran across
some old posts saying that stunnel by default has a hard limit of
around 500 connections and, to get around this, to set FD_SETSIZE at
compile time (I found this on the troubleshooting page -
http://www.stunnel.org/faq/troubleshooting.html).  However, one of the
release notes recently also had a comment saying 'no more FD_SETSIZE
limit!' - http://www.mail-archive.com/openssl-users@openssl.org/msg38373.html.
 So my questions are:

1) Does FD_SETSIZE still exist in Stunnel 4.34 and could it be a
reason why I am seeing a limit on the number of people that can make a
connection?  I already tried running stunnel after setting ulimit -Hn
and ulimit -Sn to 4096, and it did not seem to make a difference.

2) More noobish question - how do I set the FD_SETSIZE at compile
time?  I saw in the troubleshooting that it said to do
"-DFD_SETSIZE=4096" at compile time.  Is this something I should be
adding in one of the Makefiles?

Some more info about my setup:
- I am using stunnel as a layer in front of Node.js to secure
websockets and HTTP connections.
- I'm running stunnel 4.34
- I am running stunnel from a startup script in /etc/init.d - it runs
as a daemon process
- I run stunnel with no params, but with this config file -
- uname -a output:
Linux gomockingbird.com #1 SMP Tue Nov 10 16:12:12
UTC 2009 i686 GNU/Linux

- gcc -v output:
Using built-in specs.
Target: i486-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu
--enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr
--enable-shared --with-system-zlib --libexecdir=/usr/lib
--without-included-gettext --enable-threads=posix --enable-nls
--with-gxx-include-dir=/usr/include/c++/4.3 --program-suffix=-4.3
--enable-clocale=gnu --enable-libstdcxx-debug --enable-objc-gc
--enable-mpfr --enable-targets=all --with-tune=generic
--enable-checking=release --build=i486-linux-gnu --host=i486-linux-gnu
Thread model: posix
gcc version 4.3.3 (Ubuntu 4.3.3-5ubuntu4)

- openssl version output:
OpenSSL 0.9.8g 19 Oct 2007

Thanks in advance for any help!

-- Saikat

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