I've tested the attached patch for the ptlib problem I encountered ( https://sourceforge.net/p/opalvoip/bugs/496/ ) . I've tested it, found it working, and I am currently running it on production, happily going on with >2400 open files. When the next version of h323plus is released and ptlib version recomended for it is determined I will port it again and republish. Currently the patch applies cleanly to ptlib 2.12.8 too: ~/tmp/ptlib-2.12.8$ patch -p1 -i ../ptlib-2.10.9-fortify-source-fd-set.patch patching file include/ptlib/socket.h Hunk #1 succeeded at 555 (offset 80 lines). patching file src/ptlib/common/sockets.cxx Hunk #1 succeeded at 766 (offset -16 lines). patching file src/ptlib/msos/winsock.cxx Hunk #1 succeeded at 155 (offset 40 lines). Hunk #2 succeeded at 174 (offset 40 lines). patching file src/ptlib/unix/socket.cxx Hunk #1 succeeded at 130 (offset 13 lines). And also to the trunk: ~/tmp/ptlib-trunk$ patch -p1 -i ../ptlib-2.10.9-fortify-source-fd-set.patch patching file include/ptlib/socket.h Hunk #1 succeeded at 555 (offset 80 lines). patching file src/ptlib/common/sockets.cxx Hunk #1 succeeded at 774 (offset -8 lines). patching file src/ptlib/msos/winsock.cxx Hunk #1 succeeded at 155 (offset 40 lines). Hunk #2 succeeded at 174 (offset 40 lines). patching file src/ptlib/unix/socket.cxx Hunk #1 succeeded at 141 (offset 24 lines). although presently I have not got the resources to test it. Francisco Olarte.