On Nov 16, 2007 12:36 PM, Sebastian Hagedorn <[EMAIL PROTECTED]> wrote: > --On 16. November 2007 11:27:09 +0100 Sebastian Hagedorn > <[EMAIL PROTECTED]> wrote: > > >> 1) Since it only happens on dialup connections, could it be that the > >> dialin router at the providers end sends TCP/RST when a client hangs up > >> and those packets are filtered somewhere, maybe on your firewall? > > > > OK, let's run with that one. > > > > a) We don't really have a firewall, we only use ACLs on the Cisco > > routers. You can't even filter TCP/RST there. > > > > b) Even *if* a TCP/RST had been dropped, lost or whatever, the server > > *still* should timeout eventually! > > I just had a discussion with a colleague regarding this. He made two > observations: > > 1. In the absence of the SO_KEEPALIVE option it is entirely possible that a > TCP connection remains ESTABLISHED even when the other side has gone.
I said that socket should timeout, but this is true only when the protocol (TCP here) require a response (usualy AK here) or at connection establishement. On the contrary it should stay open indefinitely util something happens. Router doing NAT can drop a too old connection, because it has to maintains a NAT table and make some cleanup time to time, this where "KEEPALIVE" become usefull. > > This may not be a solution to this particular problem, but it made me > wonder why Cyrus does *not* use SO_KEEPALIVE. Is there a downside to it? Cyrus has already a built-in time out, it seems a lite conflicting to actively maintains the connection until it drop it itself ! This is the works of the client to actively maintains the connection, if it want it ! > > 2. The stack trace looks garbled: > > (gdb) bt > #0 0x0079f41e in __read_nocancel () from /lib/tls/libc.so.6 > #1 0x00d0b2f7 in BIO_new_socket () from /lib/libcrypto.so.4 > #2 0x00d092b2 in BIO_read () from /lib/libcrypto.so.4 > #3 0x005dae13 in ssl23_read_bytes () from /lib/libssl.so.4 > #4 0x005d9c51 in ssl23_get_client_hello () from /lib/libssl.so.4 > #5 0x005d9712 in ssl23_accept () from /lib/libssl.so.4 > #6 0x005ddc9a in SSL_accept () from /lib/libssl.so.4 > #7 0x08052cb3 in shut_down () > #8 0x0804e513 in shut_down () > #9 0x0804d58c in ?? () > #10 0x00000001 in ?? () > #11 0x082ee848 in ?? () > #12 0x00000000 in ?? () > > He suggested that the trace is unreliable. Perhaps a bug in RHEL 3's > version of OpenSSL messes up the stack. That would also explain why nobody > else seems to have this problem. > > I think I will try one more approach: I reverted cyrus.conf to not use "-U > 1" anymore, so that processes should be reused. I will strace one of the > pop3d processes in the hope that it gets stuck. That way I should be able > to see where things go wrong. If the process terminates normally I will try > with another one. If that doesn't go anywhere, I guess I'll drop this You could try to replace imapd by a home made script, something like . mv imapd imapd_ echo exec strace -o /tmp/imapd.$$ imapd_ $* > imapd chmod imapd a+x > investigation. We will upgrade to RHEL 5 some time next year, so hopefully > that will bring new bugs :-) Sorry but I dont understand what you are complaining about! Is-it because the imap or pop client is loosing its connection and this disturb the user or just because you are getting some sleeping processes ? Or both :-) Do you have a "timeout" option in your imapd.conf to force the imap/pop server to autologout ? Regards. Alain > > -- > .:.Sebastian Hagedorn - RZKR-R1 (Gebäude 52), Zimmer 18.:. > Zentrum für angewandte Informatik - Universitätsweiter Service RRZK > .:.Universität zu Köln / Cologne University - ✆ +49-221-478-5587.:. > .:.:.:.Skype: shagedorn.:.:.:. > ---- > Cyrus Home Page: http://cyrusimap.web.cmu.edu/ > Cyrus Wiki/FAQ: http://cyrusimap.web.cmu.edu/twiki > List Archives/Info: http://asg.web.cmu.edu/cyrus/mailing-list.html > -- Alain Spineux aspineux gmail com May the sources be with you ---- Cyrus Home Page: http://cyrusimap.web.cmu.edu/ Cyrus Wiki/FAQ: http://cyrusimap.web.cmu.edu/twiki List Archives/Info: http://asg.web.cmu.edu/cyrus/mailing-list.html
