February 2012 - dovecot

[Dovecot] How to limit max number of connections for ip address
by Wilberth Perez 25 Feb '12

25 Feb '12

Hi List: Does any one , knows if is possible configure dovecot for limit max number of connections for IP address? I would like to prevent future fork-bombing attacks for pop3 and imap login process in my email server. Our dovecot version is : 1.2.10 Thanks, Wilberth.

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[Dovecot] How to achieve proper privilege separation?
by "Tóth Attila" 24 Feb '12

24 Feb '12

I'm using a simple mbox config with regular Unix users and pam authentication. I'm also using grsecurity. That's why I see what dovecot does in which users' name. As times goes by and new versions are coming I can frustratedly see, that more and more tasks are performed as root. Why? When I used 1.x series of Dovecot, imap process started in the name of the user whose mbox was accessed. Now I can see, that nearly every task is performed by root. Why? It even tampers with the mail directories of each user as root instead of the user as it was usual long before. Please let me know how should I change the config to make dovecot stop using root privileges and revert it back to the old behavior. Thanks for your help: Dw. Here's my current config: dovecot -n # 2.0.17 (684381041dc4+): /etc/dovecot/dovecot.conf # OS: Linux 3.2.6-hardened i686 Gentoo Base System release 2.0.3 auth_socket_path = /var/run/dovecot/auth-userdb auth_verbose = yes auth_worker_max_count = 16 base_dir = /var/run/dovecot/ disable_plaintext_auth = no first_valid_gid = 99 first_valid_uid = 1000 hostname = host.name last_valid_gid = 65533 last_valid_uid = 1003 listen = * mail_access_groups = mail mail_full_filesystem_access = yes mail_gid = mail mail_location = mbox:~/mail/:INBOX=/var/spool/mail/%u mail_max_keyword_length = 150 mail_privileged_group = mail mail_uid = mail passdb { args = * driver = pam } plugin { sieve = ~/.dovecot.sieve sieve_dir = ~/sieve } postmaster_address = postmaster(a)host.name protocols = imap service auth-worker { user = root } service imap-login { inet_listener imap { port = 143 } inet_listener imaps { port = 993 ssl = yes } service_count = 1 vsz_limit = 16 M } service imap { process_limit = 4 vsz_limit = 64 M } ssl_cert = </etc/apache2/ssl/cert-file.pem ssl_key = </etc/apache2/ssl/key-file.pem userdb { driver = passwd } verbose_proctitle = yes protocol lda { mail_plugins = sieve } protocol imap { imap_client_workarounds = delay-newmail tb-extra-mailbox-sep tb-lsub-flags imap_max_line_length = 64 k -- dr Tóth Attila, Radiológus, 06-20-825-8057 Attila Toth MD, Radiologist, +36-20-825-8057

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[Dovecot] From Maildir back to smtp
by Marc Perkel 24 Feb '12

24 Feb '12

Not sure how this can be done. Right now I'm running a free backup MX record service. People point their high MX records to my servers and if they go down we store the email. When they come back up it's delivered. What I want to do is have a premium service that would allow them to view through IMAP the stored email. In order to do that I would have to deliver the email locally to a dovecot server - to a single account perhaps - and they can view/forward/delete etc. But - when their server comes back online I'd like to gather up all the delivered email stored in Maildir format and run it back into smtp for delivery. Has anyone even done something like this? Or is there an easier way that I'm missing? Thanks in advance

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[Dovecot] dsync 2.0.x versus 2.1.x field report
by Michael Grimm 24 Feb '12

24 Feb '12

Hi -- I used to run two mailservers with identical MX priorities (poor man's fail-over approach) with Maildir mail folders accessed by Dovecot. Synchronization has been achieved using unison, mirroring all files except dovecot index files. Once in a while some oddities could be observed, like reappearing of deleted mails, duplicates and such alike. But the all-over performance was quite good. Then I wanted to migrate to mdbox, and I became interested in dsync. I did start with 2.0.16 a couple of month ago, and recently upgraded to 2.0.18. My experience with the 2.0.x dsync version is as follows (synchronization time: every minute): -- As long as mail is not stored in corresponding mailboxes at both servers at the same time, all mailboxes become synchronized perfectly well, and no oddites like reappearing of deleted mails or generation of duplicates can be observed. -- If mail is stored into corresponding mailboxes at both servers simultaneously in between two synching runs, it gets worrying. -- If I do run dsync without '-f' those two mailboxes end up in becoming asynchronous. -- If I do run dsync with '-f' both mailboxes will become synchronized let's say in 95% of all synchronization runs. BUT in 5%, I do experience asynchronicity. Here a 'doveadm force-resync' sometimes works, but not always, what worries me a lot. -- I can see the missing mail in the mdbox storage file using UNIX' little helpers but not with the help of dovecot tools. (Or I was unable to use them properly.) -- Modifying MX priorities in a way, that I do now have a primary and backup mailserver scenario, very much reduced the risk of losing legitimate mail. -- But sometimes I do lose some syslog mail being produced at the same time. Therefore I modified runtimes in way to omit synchronicity. Ok, I could have lived with that, but I was anxious to learn, if 2.1.x dsync would perform better ;-) Here my observations sofar (synchronization time: every minute): -- No losses sofar using 'doveadm sync' with '-f' -- A *lot* of reappearing deleted mails or mails moved from one mailbox to the other. -- Quite often I am unable to delete those mails using client functionality (Mail.app, Roundcube). -- In those cases one needs to stop synchronization, run 'doveadm force-resync', delete all reappearing mail (quite a lot sometimes), empty 'Deleted' folders, and finally run 'doveadm purge'. -- Running of 'doveadm sync' without '-f' doesn't improve the situation. Still I do have to struggle with reappearing mails, and sometimes with appearing duplicates. -- I do have a test setup running for 24 hours now, where I do generate test mails in a 6 minutes interval at both servers. Mails become synchronized perfectly well, irrespectively if '-f' is set or not. This is a major improvement to 2.0x. dsync (sofar). -- But running the synchronization without '-f' still shows a *lot* of reappering mail, though. I do have the feeling that dsync became very much improved with regard to missing mail in synchronization, good. But those reappearing mails make me think about switching back to 2.0.x dsync and live with the drawback of preventing mail to arrive synchronously at both servers. Is someone out there experiencing a similar behaviour with dsync 2.1.x regarding reappearing, thus indelible mail? Regards, Michael

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[Dovecot] Creating and interacting with array inside plugin
by Alex Baule 24 Feb '12

24 Feb '12

Hi Timo.... I Follow your instruction to look inside quota plugin to get the notification from dovecot that expunged a message, that's Ok. Follow the quota, it's use a array to keep all uids from a email expunged, to compare with uid that is got in notify_sync, that's OK too, but to me i need to keep uid and a char* with my body name, to erase it too. I made this: struct emexis_ids_x_uis{ uint32_t ids; char *uis_file; }; struct emexis_mailbox { union mailbox_module_context module_ctx; ARRAY_DEFINE(expunge_uids, struct emexis_ids_x_uis); }; ok, inside my expunged rewrite function i create the array like quota does, and append it to my array. struct emexis_ids_x_uis append_uis; append_uis.ids = _mail->uid; append_uis.uis_file = bodyFile; array_append(&ebox->expunge_uids, &append_uis, 1); But when i do a foreach in this Array, my ids is OK, but my uis_file has tha same value every time (the value is the lasted value inserted). Append to UID array (156) --> (/storage/gss/emexis/common/t/33/88/t33889eb1bccd28fd6643ebc3ecf548b12a1ad095) Append to UID array (157) --> (/storage/gss/emexis/common/t/e3/35/te335c20e978e12d37ad0a35ae009245cd34080c0) Append to UID array (158) --> (/storage/gss/emexis/common/t/0b/83/t0b83efc253c34db35843fc89b655586d628cccaf) Calling Sync Expunged --> (156) Sync Expunged (156 == 156) --> (/storage/gss/emexis/common/t/0b/83/t0b83efc253c34db35843fc89b655586d628cccaf) Sync Expunged Match (156 == 156) --> (/storage/gss/emexis/common/t/0b/83/t0b83efc253c34db35843fc89b655586d628cccaf) Sync Expunged (157 == 156) --> (/storage/gss/emexis/common/t/0b/83/t0b83efc253c34db35843fc89b655586d628cccaf) Sync Expunged (158 == 156) --> (/storage/gss/emexis/common/t/0b/83/t0b83efc253c34db35843fc89b655586d628cccaf) Finish Calling Sync Expunged --> (156) Can i use a struct as a array Item ?? something is wrong with my array creation, append and etc ? Tks Timo !!

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Re: [Dovecot] Why is dovecot involved in my smtp process
by Joseph Tam 24 Feb '12

24 Feb '12

From: "Peter A. Giessel" <pgiessel(a)mac.com>: > Not totally true. Typical cyrus sasl2 implementation used with > sendmail uses an imap server for smtp authentication. I recall having > to tweak the sasl2 configuration on my own sendmail server to talk > correctly with dovecot. I don't recall the exact tweaks. Just to make it clear to the OP, I have a Dovecot/Sendmail/SASL working just fine (which is independent of dovecot). I suspect Peter hit the nail on the head here. Look at the contents of $SASL_INSTALL/lib/Sendmail.conf Mine is (only) pwcheck_method:saslauthd which I think looks up my name service backend via the login and plain plugins. I'm a little hazy on how this was set up, but if you are able to successfully login without dovecot, then it appears you have some sort of authentication stack that will try IMAP first, then fallback to your the other method. Joseph Tam <jtam.home(a)gmail.com>

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[Dovecot] Settings for authentication without an extra password file
by Keith Christian 24 Feb '12

24 Feb '12

Hello, I'm new to dovecot, and, due to having an older version of an OS installed on a test server, I'll be using an older version of dovecot (dovecot-1.0-1.2) to provide IMAP services. On this wiki page (http://wiki.dovecot.org/BasicConfiguration?highlight=%28passwd.dovecot%29) There are instructions for creating a separate dovecot password file: echo "$USER:{PLAIN}password" > passwd.dovecot sudo mv passwd.dovecot /etc So, it appears that two password files will be needed, one for dovecot and one for regular system logins. Is the statement above correct, or am I misreading something? Is there a setting in dovecot.conf which will authenticate IMAP using /etc/password and /etc/shadow, without a separate dovecot password file? ========Keith

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[Dovecot] Why is dovecot involved in my smtp process
by Steve Campbell 23 Feb '12

23 Feb '12

I've been trying to get smtp auth set up for days. All my sendmail and sasl2 stuff seems to be proper, but the user can't use the system on port 587, which is where I require authorization. Now I see where messages are in my maillog of the type: auth: pam_unix(dovecot:auth) : authentication failure ........ Why is dovecot involved in my smtp processes and how do I fix this. I've got some very mad users. The 10-auth.conf file is pretty much stock except for allowing plain text logins. steve campbell

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[Dovecot] Can't connect to my mail server (postfix + dovecot, IMAP) with Thunderbird
by GASPARD Kévin 23 Feb '12

23 Feb '12

I'm sorry, some one tell me my netstat (on IRC) is useless. Also my pastes will be destroyed in something like one day, that's stupid (that's originally for IRC), so this is the output of my : dovecot -n : http://pastebin.com/Tewcb7bm telnet : http://pastebin.com/6gY2puxF netstat -Nnap | grep "dovecot" : http://pastebin.com/yx2wxfWf Sorry for the error.

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[Dovecot] Can't connect to my mail server (postfix + dovecot, IMAP) with Thunderbird
by GASPARD Kévin 23 Feb '12

23 Feb '12

Hi, I've a problem with Dovecot and Thunderbird. Actually I'm trying to setup a virtual host server mail with postfix + dovecot (2.0.9) on CentOS 6.2. This is my dovecot -n : http://pastebin.com/wZWAE5Cj (I guess the errors are not important, that's just saying there is some obsoletes values, I will fix that later until it's not inconvenient to setup correctly dovecot). I've a file to store password (/etc/dovecot/passwd) and when I'm trying to connect with telnet to my host on port 143 it works, after I can log myself with the command «a login user(a)domain.tld passwd» and it works, this is the entire output of the telnet connection : http://pastebin.com/h10cQVqf but actually when I'm trying to connect with thunderbird I've an error about the password and the login, this is a screenshoot : http://images.koshie.fr/TB_problem.png and to finish, there is nothing into the log... The password and the user are corrects ! Of course, dovecot and postfix are started, this is the netstat -a | grep "dovecot" : http://pastebin.com/bwfsS4Tf If you need more informations tell me. PS : Excuse me for my bad english, also I'm new with dovecot. Cordially, GASPARD Kévin

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