- dovecot - dovecot.org

dovecot and postfix, authentication issue
by joe a 06 Jul '23

06 Jul '23

Greetings from a new dovecot user. Have setup dovecot on openSuse 15.4 with postfix as the MTA. Both are the latest version in that distribution. Simple virtual user setup using /etc/dovecot/passwd Dovecot seems to be working and all the defined users are authenticating well enough for imapsync to migrate files to the mailboxes. However, when attempting to send test mail via postfix, only some users are authenticated and have mail delivered. Using swaks (smtp toolkit) the failures are: 550 5.1.1 <some.user(a)mydomain.com>: Recipient address rejected: User unknown in local recipient table I'm puzzled, probably some simple thing overlooked. To avoid clutter, I won't include postfix items unless asked. dovecot --version 2.3.20 (80a5ac675d) dovecot -n # 2.3.20 (80a5ac675d): /etc/dovecot/dovecot.conf # Pigeonhole version 0.5.20 (149edcf2) # OS: Linux 5.14.21-150400.24.66-default x86_64 # Hostname: flitch auth_verbose = ob-fuskate disable_plaintext_auth = no first_valid_uid = 100 info_log_path = /var/log/dovecot-info.log log_path = /var/log/dovecot.log mail_location = maildir:~/Maildir managesieve_notify_capability = mailto managesieve_sieve_capability = fileinto reject envelope encoded-character vacation subaddress comparator-i;ascii-numeric relational regex imap4flags copy include variables body enotify environment mailbox date index ihave duplicate mime foreverypart extracttext namespace inbox { inbox = yes location = mailbox Drafts { special_use = \Drafts } mailbox Junk { special_use = \Junk } mailbox Sent { special_use = \Sent } mailbox "Sent Messages" { special_use = \Sent } mailbox Trash { special_use = \Trash } prefix = } passdb { driver = pam } passdb { args = /etc/dovecot/passwd driver = passwd-file } plugin { sieve = file:~/sieve;active=~/.dovecot.sieve } protocols = imap lmtp service auth { unix_listener /var/spool/postfix/private/auth { group = postfix mode = 0660 user = postfix } } service lmtp { unix_listener /var/spool/postfix/private/dovecot-lmtp { group = postfix mode = 0600 user = postfix } } ssl = no ssl_cipher_list = ALL:!aNULL:!eNULL:!EXPORT:!DES:!3DES:!MD5:!PSK:!RC4:!ADH:!LOW@STRENGTH ssl_options = no_compression ssl_prefer_server_ciphers = yes userdb { driver = passwd } userdb { args = uid=vmail gid=vmail home=/home/vmail/%u driver = static }

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director_username_hash usable variables
by Stefano Cecconello 06 Jul '23

06 Jul '23

Hi, From the documentation of the director_username_hash core setting ( https://doc.dovecot.org/settings/core/#core_setting-director_username_hash ), it seems that it is possible to use some variables for the hashing of the username from a proxy\director : . Variables that can be used for this setting: * Global variables * %{user}, %u \ Username (username@domain) * %{username}, %n \ Username * %{domain}, %d \ Domain . If i need to use in the hash calculation some variables that are not global, like domain_first \ orig_username authentication_variables ( https://doc.dovecot.org/configuration_manual/config_file/config_variables/#a uthentication-variables ), are those be parsed\read from the director_hash_username settings ? Or the only variables allowed to be used are : * %{user}, %u \ Username (username@domain) * %{username}, %n \ Username * %{domain}, %d \ Domain * Global: %% * Global: env:<name> * Global: uid * Global: gid * Global: pid * Global: hostname In order to see if these variables are read\parsed during the hashing, somebody know if there is a way to log their value in the dovecot log ? Thanks Stefano

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Chrooting
by Alexey Vlasov 30 Jun '23

30 Jun '23

Hi, I have the following hier for chrooting local users: /var/mail/.u336084 /var/mail/.u336084/bin /var/mail/.u336084/dev [cut here] /var/mail/.u336084/proc /var/mail/.u336084/var/ [cut here] /var/mail/.u336084/var/mail/ /var/mail/.u336084/var/mail/u336084 /var/mail/.u336084/var/mail/u336084/Mail /var/mail/.u336084/Mail -> var/mail/u336084/Mail (symlink) passwd file: u336084:x:1340334:255::/var/mail/.u336084:/bin/bash Chroot works fine, for SSH, FTP and etc, for example: # chroot /var/mail/.u336084 /bin/bash Given the current hierarchy, is it possible to tell the dovecot to do the same chroot? I found strange behavior that users cannot delete IMAP-folders: [pid 25055] stat("/var/mail/.u336084/Mail/.www1", {st_mode=S_IFDIR|0700, st_size=167, ...}) = 0 [pid 25055] stat("/var/mail/.u336084/Mail/.Trash.www1", 0x7ffeddc3d5c0) = -1 ENOENT (No such file or directory) [pid 25055] stat("/var/mail/.u336084/Mail/.Trash", {st_mode=S_IFDIR|0777, st_size=198, ...}) = 0 [pid 25055] fcntl(16, F_SETLK, {l_type=F_UNLCK, l_whence=SEEK_SET, l_start=0, l_len=0}) = 0 [pid 25055] fcntl(16, F_SETLK, {l_type=F_WRLCK, l_whence=SEEK_SET, l_start=0, l_len=0}) = 0 [pid 25055] fstat(16, {st_mode=S_IFREG|0600, st_size=0, ...}) = 0 [pid 25055] stat("/var/mail/.u336084/Mail/mailboxes.lock", {st_mode=S_IFREG|0600, st_size=0, ...}) = 0 [pid 25055] unlink("/var/mail/.u336084/Mail/mailboxes.lock") = 0 [pid 25055] close(16) = 0 [pid 25055] write(7, "96 NO [CANNOT] Renaming not supported across conflicting directory permissions (0.002 + 0.000 + 0.001 secs).\r\n", 110) = 110 [pid 25055] epoll_wait(11, [{EPOLLIN, {u32=1794732256, u64=94916277006560}}], 7, 1800000) = 1 Btw I don't see any conflicting dirs: root@:/var/mail/u336084# ls -ld /var/mail/.u336084/Mail/.www1 drwx------ 5 u336084 virtmail 167 Jun 27 13:26 /var/mail/.u336084/Mail/.www1 root@:/var/mail/u336084# ls -ld /var/mail/.u336084/Mail lrwxrwxrwx 1 u336084 virtmail 26 Apr 28 21:43 /var/mail/.u336084/Mail -> var/mail/u336084/Mail root@:/var/mail/u336084# ls -ld Mail drwx------ 16 u336084 virtmail 4096 Jun 30 01:25 Mail All folders have right owner u336084. With this configuration Courier worked properly, I noteced the problem after migration to Dovecot. Thanks in advance.

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Warning sqlpool(mysql): Query failed
by Alessio Cecchi 27 Jun '23

27 Jun '23

Hi, with the last dovecot version (2.3.13) I see many of this warnings via "doveadm log errors": Feb 17 03:26:28 Warning: dict(31513): conn unix:dict (pid=31330,uid=95): dict(mysql)<email1(a)company1.com>: sqlpool(mysql): Query failed, retrying: MySQL server has gone away (idled for 679 secs) Feb 17 03:48:53 Warning: dict(31013): conn unix:dict (pid=31805,uid=95): dict(mysql)<email2(a)company2.com>: sqlpool(mysql): Query failed, retrying: MySQL server has gone away (idled for 685 secs) Feb 17 03:54:12 Warning: dict(32529): conn unix:dict (pid=3147,uid=95): dict(mysql)<email3(a)company3.com>: sqlpool(mysql): Query failed, retrying: MySQL server has gone away (idled for 670 secs) What do they mean? I thinks are related to inactivity timeout on mysql server (where I have a wait_timeout=600), but these warnings could be problems or can be fixed with some setting in dovecot? My dovecot configuration about dict: dict { acl = mysql:/etc/dovecot/dovecot-dict-sql.conf.ext expire = mysql:/etc/dovecot/dovecot-dict-sql.conf.ext sieve = mysql:/etc/dovecot/dovecot-dict-sieve-sql.conf.ext sqlquota = mysql:/etc/dovecot/dovecot-dict-sql.conf.ext } plugin { [...] acl_shared_dict = proxy::acl expire_dict = proxy::expire quota2 = dict:Quota Usage::noenforcing:proxy::sqlquota sieve = file:~/sieve;active=~/.dovecot.sieve sieve_before = dict:proxy::sieve;name=activesql [...] } service dict { process_limit = 500 unix_listener dict { group = vmail mode = 0660 user = vmail } } Thanks -- Alessio Cecchi Postmaster @ http://www.qboxmail.it https://www.linkedin.com/in/alessice

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Re: Postfix: running a script on authentication failure
by Joseph Tam 27 Jun '23

27 Jun '23

On Thu, 22 Jun 2023, Michael Peddemors wrote: > * Use services like RATS-AUTH to block IPs that can safely be blocked as known hackers.. Cool. Are there other DNSRBLs (apart from bl.blocklist.de) that list BFD attack IPs? > * Use services like RATS-NULL (or SpamHaus DROP lists) right in the firewall level. There are SOME networks > that should simply be 'unplugged' Can't find it in https://spamrats.com/. Is it an DNSRBL or downloadable file? > * Turn off port 110 (well, all plain text authentication) 90% less email compromise reports when you do.. That will disable STARTTLS though. Even though it's not plaintext, maybe that is a good thing as it avoids MITM banner stripping attacks. Joseph Tam <jtam.home(a)gmail.com>

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Server migration, password scheme/hashing, argon2i, argon2d, argon2id, sha512, sha512-crypt, tiger2, salt?
by David Mehler 24 Jun '23

24 Jun '23

Hello, I'm migrating to a new server. It's running Debian 11 currently though that's going 12 this weekend. Currently it uses Openssl v3.0.9, and dovecot 2.3.13 and MySQL (in this case Mariadb) for storing user account information v10.6.14. My question is in regards password storage and scheme/encryption/salts. Currently they are stored in Mariadb password field with a type of varchar and a 255 character length, and are stored as SHA512-CRYPT. I'm wondering if I should keep this as is or when I migrate go to another scheme? I'm thinking argon2i, argon2d, argon2id, sha512, sha512-crypt, tiger2, saltt? Discussion/opinions welcome. Thanks. Dave.

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configuring Dovecot submission service
by Computerisms Corporation 23 Jun '23

23 Jun '23

Hi Dovecot Gurus, I have been playing around with the submission service. I have managed to get all the things working that I want working with two exceptions. I have not found (or possibly I have overlooked) solutions in the documentation or discussions on the 'net. First; I would like to be able to authenticate against my backend MTA using the user-supplied credentials. I have tried setting submission_relay_user as %u and submission_relay_password as %w, but these seem to be passed through as literal strings, and of course my backend MTA has no idea who %u is. I found a post from 2019 that indicates passing the submission_relay_user/password to the backend is not a supported function, but hoping that maybe that is outdated info. I also found: https://doc.dovecot.org/3.0/configuration_manual/authentication/proxies/ Which seems to indicate it could pass credentials to a non-Dovecot MTA backend, but I am not really clear from the docs on how to set that up, and I did not find any relevant examples to work from. Seems like it would be setting up a Director service, maybe? I have done that before and I do manage multiple email servers, but none of them is clustered or configured to be interoperable, so not sure if this is a viable approach. Second; I am wondering about the possibility of having multiple submission_relay_host entries. For example if I have dovecot submission services running on my standard port 587 and 465 connect to a relay on the same box through localhost, but could I have another submission service running on another port, say 5587, and relay all traffic received on that port through a completely different host? I am thinking I could set that up by running a separate instance of dovecot for just that service, but maybe there is a more suitable way? I don't have a solid use-case for this in mind at the moment, but given that I do manage multiple email servers, I am thinking that if this is possible it might provide some useful corner-case configurations down the road. Thank you for reading my post, any thoughts, information, or pointers to relevant documentation would be most appreciated. -- Bob Miller 867-334-7117 www.computerisms.ca

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Postfix: running a script on authentication failure
by André Rodier 22 Jun '23

22 Jun '23

Hello, all. I just set-up a new server, running postfix, with submission(s) activated on standard ports (587, 465) Shortly after it has been setup, I see brute force attacks (not surprising) from a whole /24 network (more surprising). I carefully checked the logs, and see the modus operandi, which basically loop across the IP addresses in the network, to avoid being blacklisted by tools like fail2ban. And it is true, even with fail2ban activated, no IP is blacklisted. By activating verbose logging, I see multiple user names are tried, not only passwords. Is there any way, with postfix, to run a script on authentication failure, with information like the IP address and the username passed, for instance. I basically need features that fail2ban doesn't offer - I would like to not rely on reading logs, removing one step and acting more pro-actively. - If a script is called on authentication failure, it is fairly easy to use a Levenshtein distance to differentiate between a user having lost his password and a brute force attack. - If I log all the failure in a database, with the IP address, and the whois information, the script would take decision according to the whois information. What are you using on your side ? - Do you know any service, that I could use, to get the network to ban from an IP address reputation, something like crowdsec, for instance ? - Anyone has success with Suricata, Snort, or a tool like this ? Please, do not suggest third party hosted services, I want to be part of my self-hosting solution. Kind regards, André

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Postfix: running a script on authentication failure
by André Rodier 22 Jun '23

22 Jun '23

Hello, all. I just set-up a new server, running postfix, with submission(s) activated on standard ports (587, 465) Shortly after it has been setup, I see brute force attacks (not surprising) from a whole /24 network (more surprising). I carefully checked the logs, and see the modus operandi, which basically loop across the IP addresses in the network, to avoid being blacklisted by tools like fail2ban. And it is true, even with fail2ban activated, no IP is blacklisted. By activating verbose logging, I see multiple user names are tried, not only passwords. Is there any way, with postfix, to run a script on authentication failure, with information like the IP address and the username passed, for instance. I basically need features that fail2ban doesn't offer - I would like to not rely on reading logs, removing one step and acting more pro-actively. - If a script is called on authentication failure, it is fairly easy to use a Levenshtein distance to differentiate between a user having lost his password and a brute force attack. - If I log all the failure in a database, with the IP address, and the whois information, the script would take decision according to the whois information. What are you using on your side ? - Do you know any service, that I could use, to get the network to ban from an IP address reputation, something like crowdsec, for instance ? - Anyone has success with Suricata, Snort, or a tool like this ? Please, do not suggest third party hosted services, I want to be part of my self-hosting solution. Kind regards, André

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el9 rpms
by Marc 21 Jun '23

21 Jun '23

Is there a specific reason why there are (still) no el9 packages? https://repo.dovecot.org/ce-2.3.17/centos/ https://repo.dovecot.org/ce-2.3-latest/rhel/

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