April 2019 - dovecot - dovecot.org

Post login scripts environment
by André Rodier 14 Apr '19

14 Apr '19

Dear Dovecot users, I am running Dovecot 2.2.27 on Debian Stretch, no issue so far. I wonder if there is a way to pass the remote IP address, in an environment variable, in the post login script. My Post login scripts are working well, except that when the server is accessed through a webmail (Roundcube or SOGo), the remote IP address is systematically 127.0.0.1. The other question I have is, is it possible to pass the user agent of the email client used to access the server? I know this can be easily forged, but I would like to log it. Thanks for your insight. -- André Rodier

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Using userdb/passdb data in director_username_hash
by Mark Moseley 12 Apr '19

12 Apr '19

TL;DR: Can director_username_hash use %{userdb:...} or %{passdb:...} ? ==================================== This is on Ubuntu Precise, running dovecot 2.2.36. It's a fully production, director-ized env, so assume everything is working correctly. Happy to post doveconf if it's relevant but wanted to ask a general question first. I was curious if there's a way to get userdb/passdb data into director_username_hash. Currently, we've got default hashing (on %u). I'm returning a SQL field called 'real_username' (the owner of the mailbox, so almost never the same as %u). I'd like (for mdbox reasons) to hash on that rather than %u. My test SQL is returning (this is just a chunk -- it's duplicated for testing): UserName AS userdb_real_username, UserName AS real_username I can see in my director boxes that it's at least picking up the latter: passdb out: PASS 1 user=tesbox(a)mailbox.com proxy=y real_username=testuser Is it possible to inject 'real_username' into director_username_hash? That is, I'd rather hash on 'testuser' instead of 'testbed'. I've been trying different permutations on my director boxes with no luck. director_username_hash = %{userdb:real_username} director_username_hash = %{passdb:real_username} director_username_hash = %{userdb:userdb_real_username} director_username_hash = %{passdb:userdb_real_username} With any of those settings, every mailbox gets hashed to the same backend, so I'm guessing it's not getting anything useful (i.e. probably resolving to the same empty string and hashing on that -- or perhaps is just hashing on the literal string, e.g. "%{userdb:real_username}" ). And I'm not even sure if director_username_hash has access to any passdb/userdb data. Is there a debug setting that would show what string director is using to do the hashing? Current debug settings are: auth_debug = yes auth_debug_passwords = yes mail_debug = yes but not a peep as to the string that director is hashing on.

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Migrating from external server to Dovecot (doveadm sync issues)
by Sven Strickroth 12 Apr '19

12 Apr '19

Hi, I'm experiencing serious issues when using doveadm sync not working at all or do not properly sync. I wanted to use this for migrating external mailboxes to my server (in order to overcome the time when some servers/clients still use the old server and some already the my server). I tried to find a few steps in order to replicate this: For testing purposes I simulate both the remote and local server on my Dovecot instance. I created remote(a)DOMAIN.TLD and local(a)DOMAIN.TLD both use mdbox and are empty (i.e., the mail_location is still non-existent). Then I send two mails to remote(a)DOMAIL.TLD (Subjects: Test1 and Test2). Start backup remote IMAP account (remote(a)DOMAIN.TLD) to local account (local(a)DOMAIN.TLD) * doveadm -o imapc_user="remote(a)DOMAIN.TLD" -o imapc_password="PW" -o imapc_host="localhost" -o mail_prefetch_count=20 -o imapc_features="rfc822.size fetch-headers" backup -R -u local(a)DOMAIN.TLD imapc: (without this I often got errors such as "Error: Backend didn't update mailbox Trash GUID" on sync runs, which seems to be an unrecoverable error). Now the two mailboxes seem to be the same (can confirm this when logging into the two mailboxes). Now, run first sync: * doveadm -o imapc_user="remote(a)DOMAIN.TLD" -o imapc_password="PW" -o imapc_host="localhost" -o mail_prefetch_count=20 -o imapc_features="rfc822.size fetch-headers" sync -R -u local(a)DOMAIN.TLD imapc: Seems to work and does nothing at the moment. Deliver one message to local(a)DOMAIN.TLD (Subject Test3). * doveadm -o imapc_user="remote(a)DOMAIN.TLD" -o imapc_password="PW" -o imapc_host="localhost" -o mail_prefetch_count=20 -o imapc_features="rfc822.size fetch-headers" sync -R -u local(a)DOMAIN.TLD imapc: Now Test1,2,3 are in both mailboxes (further runs do change nothing). Everything OK up the here. Now deliver one messages to remote(a)DOMAIN.TLD (Test4) and delete one old message (Test3). Deliver two messages to local(a)DOMAIN.TLD (Subjects Test5 and Test6) and delete one message (Test2). In sum both mailboxes look like this: remote(a)DOMAIN.TLD has Test1,2,4 and local(a)DOMAIN.TLD has 1,3,5,6. Now sync: * doveadm -o imapc_user="remote(a)DOMAIN.TLD" -o imapc_password="PW" -o imapc_host="localhost" -o mail_prefetch_count=20 -o imapc_features="rfc822.size fetch-headers" sync -R -u local(a)DOMAIN.TLD imapc: dsync(local(a)DOMAIN.TLD): Warning: Mailbox changes caused a desync. You may want to run dsync again: 3 UIDs changed due to UID conflicts Rerun again and see that mails start duplicating and deletings are not synced: remote(a)DOMAIN.TLD: Test1,2,4,3,5,6,5,6,6,5,3,4 (12 mails) and local(a)DOMAIN.TLD: 1,6,4,3,5,6,4,3,5,6,5 (11 mails) When I re-run again I sometimes see the above error message again, mails keep duplicating in both mailboxes and the mailboxes are not synced at all. Am I using doveadm sync wrongly? Is there a way to use "sync" directly w/o backup from the beginning (i.e., how to get rid of the error "Error: Backend didn't update mailbox Trash GUID"). Context: # 2.2.27 (c0f36b0): /etc/dovecot/dovecot.conf # Pigeonhole version 0.4.16 (fed8554) # OS: Linux 4.9.0-8-amd64 x86_64 Debian 9.8 imap_client_workarounds = delay-newmail I can't upgrade to latest Dovecot right now. :( -- Best regards, Sven Strickroth PGP key id F5A9D4C4 @ any key-server

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Mail account brute force / harassment
by Marc Roos 12 Apr '19

12 Apr '19

Say for instance you have some one trying to constantly access an account Has any of you made something creative like this: * configure that account to allow to login with any password * link that account to something like /dev/zero that generates infinite amount of messages (maybe send an archive of virusses?) * transferring TB's of data to this harassing client. I think it would be interesting to be able to do such a thing.

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Emails redownloading
by azurit＠pobox.sk 12 Apr '19

12 Apr '19

Hi, recently, we had a problem on one of our mail servers and, after reboot, HDD with emails wasn't mounted into system. Until we fixed it, LOTS of users logged in (Dovecot allowed login and recreated directory structure of mailboxes) and saw empty mailboxes. Now they are redownloading all email, which isn't fun, as it's about 2 TB of data. Anyway, is there a way how to prevent this in the future? Can i set Dovecot to disallow logins in such situations? Thanks. azur

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Doveadm stats
by ＠lbutlr 12 Apr '19

12 Apr '19

Are there any examples of the utility of doveadm stats? in the man page: > dump accepts following types: command, session, user, domain, ip and > global. > > Filter can be > > user=<wildcard> > Match given user. I've tried the following commands after looking at the (sparse and example-less) man page. # doveadm stats dump metric_name field count sum min max avg median stddev %95 # doveadm stats dump user Error: Extraneous arguments found: user # doveadm stats dump user user="*" Error: Extraneous arguments found: user user=* # doveadm stats dump global Error: Extraneous arguments found: global # doveadm stats dump global user="*" Error: Extraneous arguments found: global user=* # I assume there is more to the configuration for stats than merely making it not report an error. So, the first question is what sorts of stats would be most likely to be useful and what do I do in the configuration to get those? Second question is why is this required to be enabled if, by default, it has no functionality? -- Beware of geeks bearing .GIF's

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Mailbox INBOX: Opening INBOX failed: Mailbox doesn't exist: INBOX. Maybe master user + namespace problem?
by Usuario prueba 12 Apr '19

12 Apr '19

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Secure Client-Initiated Renegotiation
by sergio 12 Apr '19

12 Apr '19

Hello. I've just tested my system that runs dovecot 2.3.4.1 on debian buster with testssl.sh (https://testssl.sh/) and is says: Secure Renegotiation (CVE-2009-3555) not vulnerable (OK) Secure Client-Initiated Renegotiation VULNERABLE (NOT ok), potential DoS threat Is this a configuration or a compilation issue and how to solve it? -- sergio.

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Re: High availability of Dovecot
by Gerald Galster 12 Apr '19

12 Apr '19

> Am 11.04.2019 um 11:48 schrieb luckydog xf <luckydogxf(a)gmail.com>: > > As your statement, nothing speical is needed to do except setting up DNS MX records, right? MX records are for incoming MAIL: yourdomain.com <http://yourdomain.com/> IN MX 100 mail1.yourdomain.com <http://server1.yourdomain.com/> yourdomain.com <http://yourdomain.com/> IN MX 100 mail2.yourdomain.com <http://mail2.yourdomain.com/> -> both priority 100 = 50/50 load balancing (globally, not when checked on a single resolver!) Then you need A Records (AAAA for ipv6) mail1.yourdomain.com IN A 192.168.10.1 mail2.yourdomain.com <http://mail2.yourdomain.com/> IN A 192.168.20.1 mail.yourdomain.com IN A 192.168.10.1 mail.yourdomain.com IN A 192.168.20.1 mail1/mail2 is for direct connection (MTAs) Your users (outlook, thunderbird, ...) connect to mail.yourdomain.com <http://mail.yourdomain.com/> which returns the two ip addresses. In this scenario MUA just connects to mail.yourdomain.com <http://mail.yourdomain.com/> and randomly uses one of the two ips. You can't control which one, but this gives you active/active loadbalancing. In case one server is down the MUA just uses the other ip. dsync replicates bi-directionally so that both servers are up-to-date. You don't need shared storage, every server is a copy of the other. If you want to use shared storage, then dsync is not for you because there is nothing to sync at that stage. I would use shared storage only if you need to have more than two servers. The above setup has no locking problems and is performant due to local filesystems. It depends on how many users you have and how much storage you need. You could buy two 2HE servers with 24 2.5" disks each (up to 96 with 4 HE), which may be sufficient for your needs. > User's mail store is running on shared storage, basically user's MUA connects to primary MX , the backup one is used once Primary is down. If you're not using Maildir beware of locking issues with concurrent access. It could crash indices. > It's a native HA of email system? I'll test those solution out. Yes, it works well with small setups. For big setups you'd typically use dovecot director, shared storage, object storage ... but you need more servers and it is way more complex and expensive. Best regards Gerald

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failed: read(/var/run/dovecot/dns-client)
by Laura Smith 12 Apr '19

12 Apr '19

=== dsync(foobar(a)example.com): Error: imapc(foobar.example.com:993): dns_lookup(foobar.example.com) failed: read(/var/run/dovecot/dns-client) failed: read(size=512) failed: Connection reset by peer dsync(foobar(a)example.com): Error: Failed to initialize user: imapc: Login to foobar.example.com failed: Disconnected from server === Initially I thought "oh no, not another AppArmor block". But then surely the second message would not appear if the DNS lookup was not successful ? Also "dig foobar.example.com" works fine. How should I be troubleshooting this ? And if it is still likely to be AppArmor, what is calling it ? "doveadm" itself or something else ? What does "/var/run/dovecot/dns-client" do and why doesn't dovecot use standard OS calls like everyone else ? So many questions !

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