On Nov 16, 2007 12:36 PM, Sebastian Hagedorn <Hagedorn@xxxxxxxxxxxx> wrote:> --On 16. November 2007 11:27:09 +0100 Sebastian Hagedorn> <hagedorn@xxxxxxxxxxxx> 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 theprotocol (TCP here)require a response (usualy AK here) or at connection establishement.On the contraryit should stay open indefinitely util something happens. Router doingNAT can dropa too old connection, because it has to maintains a NAT table and make somecleanup 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 activelymaintains 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_ $* > imapdchmod 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 andthis disturb the useror just because you are getting some sleeping processes ? Or both :-) Do you have a "timeout" option in your imapd.conf to force theimap/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 Spineuxaspineux gmail comMay the sources be with you----Cyrus Home Page: http://cyrusimap.web.cmu.edu/Cyrus Wiki/FAQ: http://cyrusimap.web.cmu.edu/twikiList Archives/Info: http://asg.web.cmu.edu/cyrus/mailing-list.html
