[Dovecot] server is not imap4 compatible
hello,
i have a problem with my dovecot installation.
sometimes, the thunderbird clients on windows machines complains about: "server is not imap4 compatible".
on the server, at the same time, i found this error:
Apr 20 16:21:17 harlock dovecot: imap-login: Disconnected: Shutting down: rip=192.168.0.194, lip=10.70.0.1, TLS handshake
the imap server is behind a dmz which sometimes drops connections.
the server ran without problem until i upgraded from 1.0.rc15 to 1.0.15.
after the upgrade i was forced to enhance the proc.sys.fs.inotify.max_user_instances = 1024 because i had error messages about "Inotify instance limit for user exceeded"
my question is: does the upgrade triggered a new way of communication between clients and server that exacerbates the problem of dropped connections from the DMZ server?
p.s. the dovecot configuration is:
$ sudo dovecot -n # 1.0.15: /etc/dovecot/dovecot.conf log_timestamp: %Y-%m-%d %H:%M:%S protocols: imap imaps pop3 pop3s ssl_cert_file: /etc/ssl/certs/harlock_digicert_2009.pem ssl_key_file: /etc/ssl/private/harlock_digicert_2009.key login_dir: /var/run/dovecot/login login_executable(default): /usr/lib/dovecot/imap-login login_executable(imap): /usr/lib/dovecot/imap-login login_executable(pop3): /usr/lib/dovecot/pop3-login login_max_processes_count: 256 mail_privileged_group: mail mail_location: maildir:/var/mail/vhosts/turboden.net/%n/ mail_executable(default): /usr/lib/dovecot/imap mail_executable(imap): /usr/lib/dovecot/imap mail_executable(pop3): /usr/lib/dovecot/pop3 mail_plugin_dir(default): /usr/lib/dovecot/modules/imap mail_plugin_dir(imap): /usr/lib/dovecot/modules/imap mail_plugin_dir(pop3): /usr/lib/dovecot/modules/pop3 imap_client_workarounds(default): tb-extra-mailbox-sep imap_client_workarounds(imap): tb-extra-mailbox-sep imap_client_workarounds(pop3): outlook-idle pop3_uidl_format(default): pop3_uidl_format(imap): pop3_uidl_format(pop3): %08Xu%08Xv auth default: mechanisms: plain login default_realm: DOMAIN.LOCAL username_format: %Ln@%Ud passdb: driver: pam userdb: driver: static args: uid=5000 gid=5000 socket: type: listen client: path: /var/spool/postfix/private/auth mode: 432 user: postfix group: postfix
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marco ghidinelli said the following on 21/04/09 15:28:
sometimes, the thunderbird clients on windows machines complains about: "server is not imap4 compatible".
Got same problem with a customer. After many tests I found a problem in the antivirus settings: the settings were too aggressive and made the connection with the server drop.
Ciao, luigi
/ +--[Luigi Rosa]-- \
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On Apr 21, 2009, at 9:28 AM, marco ghidinelli wrote:
on the server, at the same time, i found this error:
Apr 20 16:21:17 harlock dovecot: imap-login: Disconnected: Shutting
down: rip=192.168.0.194, lip=10.70.0.1, TLS handshake
"Shutting down" means that Dovecot really is being shut down or
restarted. Is this not an expected restart? Does it happen at the same
time always? Maybe it's some cron job.
the server ran without problem until i upgraded from 1.0.rc15 to 1.0.15.
after the upgrade i was forced to enhance the proc.sys.fs.inotify.max_user_instances = 1024 because i had error messages about "Inotify instance limit for user exceeded"
The previous version probably didn't have inotify enabled.
my question is: does the upgrade triggered a new way of communication between clients and server that exacerbates the problem of dropped connections from the DMZ server?
I think it's unlikely.
On Tue, Apr 21, 2009 at 12:26:38PM -0400, Timo Sirainen wrote:
On Apr 21, 2009, at 9:28 AM, marco ghidinelli wrote:
on the server, at the same time, i found this error:
Apr 20 16:21:17 harlock dovecot: imap-login: Disconnected: Shutting
down: rip=192.168.0.194, lip=10.70.0.1, TLS handshake"Shutting down" means that Dovecot really is being shut down or
restarted. Is this not an expected restart? Does it happen at the same
time always? Maybe it's some cron job.
no, of course this was NOT an expected restart. i thought that it was a normal disconnection between the client and the server.
the "shutting down" messages appeared even on the previous 1.0.rc15 version, but not the "server not imap4 compatible" error.
or maybe my users didn't tell me. :)
any idea?
On Apr 22, 2009, at 4:12 AM, marco ghidinelli wrote:
Apr 20 16:21:17 harlock dovecot: imap-login: Disconnected: Shutting down: rip=192.168.0.194, lip=10.70.0.1, TLS handshake
"Shutting down" means that Dovecot really is being shut down or restarted. Is this not an expected restart? Does it happen at the
same time always? Maybe it's some cron job.no, of course this was NOT an expected restart. i thought that it was a normal disconnection between the client and the server.
the "shutting down" messages appeared even on the previous 1.0.rc15 version, but not the "server not imap4 compatible" error.
or maybe my users didn't tell me. :)
any idea?
My idea is still the same: Client gets unexpectedly disconnected due
to Dovecot restart and the client thinks it's not connected to IMAP4
server. Try to figure out why Dovecot is getting restarted. It's not
doing it alone. Do you see "starting up" lines in logs showing that
the whole Dovecot was restarted? If not, do you see any "killed by
signal" lines in logs? Perhaps the whole Dovecot isn't being
restarted, but just some buggy script/program is sending SIGTERMs to
imap-login processes more or less randomly for some reason..
On Wed, Apr 22, 2009 at 10:25:41AM -0400, Timo Sirainen wrote:
On Apr 22, 2009, at 4:12 AM, marco ghidinelli wrote:
Apr 20 16:21:17 harlock dovecot: imap-login: Disconnected: Shutting down: rip=192.168.0.194, lip=10.70.0.1, TLS handshake
"Shutting down" means that Dovecot really is being shut down or restarted. Is this not an expected restart? Does it happen at the
same time always? Maybe it's some cron job.no, of course this was NOT an expected restart. i thought that it was a normal disconnection between the client and the server.
the "shutting down" messages appeared even on the previous 1.0.rc15 version, but not the "server not imap4 compatible" error.
or maybe my users didn't tell me. :)
any idea?
My idea is still the same: Client gets unexpectedly disconnected due to Dovecot restart and the client thinks it's not connected to IMAP4
server. Try to figure out why Dovecot is getting restarted.
dovecot doesn't restart, and nothing try to restart it.
It's not doing it alone.
maybe it's not a 'whole' restart, but just it drops some connections.
Do you see "starting up" lines in logs showing that the whole Dovecot was restarted?
no
If not, do you see any "killed by signal" lines in logs?
no. i got those lines only when i issue the /etc/init.d/postfix {start|restart} commands.
Perhaps the whole Dovecot isn't being restarted, but just some buggy script/program is sending SIGTERMs to imap-login processes more or less randomly for some reason..
i looked at the dovecot sources now, and i saw that:
# vi master/login-process.c +738
static int login_group_start_missings(struct login_group *group) { if (group->set->login_process_per_connection && group->processes >= group->set->login_max_processes_count && group->listening_processes == 0) { /* destroy the oldest listening process. non-listening processes are logged in users who we don't want to kick out because someone's started flooding */ if (group->oldest_prelogin_process != NULL && group->oldest_prelogin_process->initialized) login_process_destroy(group->oldest_prelogin_process); }
my login_max_processes_count was 256, and my imap-login process is about 240, now i enhanced it to 512.
am i going into the right direction?
participants (3)
-
Luigi Rosa
-
marco ghidinelli
-
Timo Sirainen