December 2021 - dovecot

Issue with SCRAM-SHA Authorization
by Thomas Schmid 03 Dec '21

03 Dec '21

Hi, I was debugging a bug report for my sieve editor implementation concerning an issue with SCRAM-SHA Authorization. But I am a bit unsure about my findings. It seems to be a server side bug. But I am wondering if I missed something. What puzzles me a bit is that SCRAM-SHA is out since ages and obviously no one ran into this issue. Which feels odd. When I try to connect to a dovecot server with enabled Authorization, then SCRAM SHA1 or SHA256 fail with a channel binding error. Authorization via SASL PLAIN works perfectly fine. So I digged into the logs. The trace is below also my findings/conclusion. The username and authorization in the trace are set to "user" the password is "pencil". Nov 24 14:00:06 auth: Debug: client in: AUTH 1 SCRAM-SHA-256 service=sieve secured=tlssession=sI9yRonRZISsEQAB lip=172.17.0.2 rip=172.17.0.1 lport=4190 rport=33892 resp=bixhPXVzZXIsbj11c2VyLHI9ZmEzZGY1NjNlZjczZTY3YjQzZThhZWRiZjUzNGI1NWIxNzIwNzU3OThjZmJiMjExNmMyMTNkMWM4NDE4MmZkOQ== (previous base64 data may contain sensitive data) Nov 24 14:00:06 auth: Debug: passwd-file(user,172.17.0.1,<sI9yRonRZISsEQAB>): Performing passdb lookup Nov 24 14:00:06 auth: Debug: passwd-file(user,172.17.0.1,<sI9yRonRZISsEQAB>): lookup: user=user file=/etc/dovecot/users Nov 24 14:00:06 auth: Debug: passwd-file(user,172.17.0.1,<sI9yRonRZISsEQAB>): Generating SCRAM-SHA-256 from user 'user', password 'pencil' Nov 24 14:00:06 auth: Debug: passwd-file(user,172.17.0.1,<sI9yRonRZISsEQAB>): Finished passdb lookup Nov 24 14:00:06 auth: Debug: Credentials: 343039362c326b3934364452546c326431765a37434b6d556c32513d3d2c46444d364f7173577035464c446e394151666554316547585045427a47566d6965673842427331456d37633d2c79766e5a4169376250392f59706c4a71597872356a79794f7a6e4c664730667636485155325a7a6975376b3d Nov 24 14:00:06 auth: Debug: client passdb out: CONT 1 cj1mYTNkZjU2M2VmNzNlNjdiNDNlOGFlZGJmNTM0YjU1YjE3MjA3NTc5OGNmYmIyMTE2YzIxM2QxYzg0MTgyZmQ5J2Q9NCskV2NuWEFVTnZxOU1EZENgM2UheVguXFw3O2JgKlg0X29gKDtBXnJrTi1xUmQ2IXgiQX5+eGU8ZlJHWSxzPTJrOTQ2RFJUbDJkMXZaN0NLbVVsMlE9PSxpPTQwOTY= Nov 24 14:00:06 auth: Debug: client in: CONT 1 Yz1iaXhoUFhWelpYSXMscj1mYTNkZjU2M2VmNzNlNjdiNDNlOGFlZGJmNTM0YjU1YjE3MjA3NTc5OGNmYmIyMTE2YzIxM2QxYzg0MTgyZmQ5J2Q9NCskV2NuWEFVTnZxOU1EZENgM2UheVguXFw3O2JgKlg0X29gKDtBXnJrTi1xUmQ2IXgiQX5+eGU8ZlJHWSxwPUcvZGZWUUlGZy9NMkpSMlpEMXM0cms4MS9jTmFMa0tuMzZFYzFlTTN1enc9 (previous base64 data may contain sensitive data) Nov 24 14:00:06 auth: Info: scram-sha-256(user,172.17.0.1,<sI9yRonRZISsEQAB>): Invalid channel binding data Nov 24 14:00:06 auth: Debug: auth(user,172.17.0.1,<sI9yRonRZISsEQAB>): Auth request finished Nov 24 14:00:08 auth: Debug: client passdb out: FAIL 1 user=user Nov 24 14:00:08 managesieve-login: Info: Disconnected: Aborted login by logging out (auth failed, 1 attempts in 2 secs): user=<user>, method=SCRAM-SHA-256, rip=172.17.0.1, lip=172.17.0.2, TLS, session=<sI9yRonRZISsEQAB> Nov 24 14:00:08 managesieve-login: Debug: SSL alert: close notify The matching trace from the client, a sieve editor (https://github.com/thsmi/sieve) is as follows: [15:000:06.192 kw53213a-qc7kf99m1lp] Client -> Server: AUTHENTICATE "SCRAM-SHA-256" "bixhPXVzZXIsbj11c2VyLHI9ZmEzZGY1NjNlZjczZTY3YjQzZThhZWRiZjUzNGI1NWIxNzIwNzU3OThjZmJiMjExNmMyMTNkMWM4NDE4MmZkOQ==" [15:000:06.202 kw53213a-qc7kf99m1lp] Server -> Client "cj1mYTNkZjU2M2VmNzNlNjdiNDNlOGFlZGJmNTM0YjU1YjE3MjA3NTc5OGNmYmIyMTE2YzIxM2QxYzg0MTgyZmQ5J2Q9NCskV2NuWEFVTnZxOU1EZENgM2UheVguXFw3O2JgKlg0X29gKDtBXnJrTi1xUmQ2IXgiQX5+eGU8ZlJHWSxzPTJrOTQ2RFJUbDJkMXZaN0NLbVVsMlE9PSxpPTQwOTY=" [15:000:06.209 kw53213a-qc7kf99m1lp] Client -> Server: "Yz1iaXhoUFhWelpYSXMscj1mYTNkZjU2M2VmNzNlNjdiNDNlOGFlZGJmNTM0YjU1YjE3MjA3NTc5OGNmYmIyMTE2YzIxM2QxYzg0MTgyZmQ5J2Q9NCskV2NuWEFVTnZxOU1EZENgM2UheVguXFw3O2JgKlg0X29gKDtBXnJrTi1xUmQ2IXgiQX5+eGU8ZlJHWSxwPUcvZGZWUUlGZy9NMkpSMlpEMXM0cms4MS9jTmFMa0tuMzZFYzFlTTN1enc9" [15:000:08.215 kw53213a-qc7kf99m1lp] Server -> Client NO "Authentication failed." According to the RFC (https://datatracker.ietf.org/doc/html/rfc5802) the initial request is defined as: (("p=" cb-name) / "n" / "y") "," [ authzid ] "," client-first-message-bare This means the decoded message from the trace is: n,a=user,n=user,r=fa3df563ef73e67b43e8aedbf534b55b172075798cfbb2116c213d1c84182fd9 The final request (which is rejected by the server with the binding error) is defined as : client-final-message-without-proof = channel-binding "," nonce [","extensions] or client-final-message = client-final-message-without-proof "," proof So the request from the trace decodes into: c=bixhPXVzZXIs,r=fa3df563ef73e67b43e8aedbf534b55b172075798cfbb2116c213d1c84182fd9'd=4+$WcnXAUNvq9MDdC`3e!yX.\\7;b`*X4_o`(;A^rkN-qRd6!x"A~~xe<fRGY,p=G/dfVQIFg/M2JR2ZD1s4rk81/cNaLkKn36Ec1eM3uzw= The channel-binding and cbind-input part are defined as: channel-binding = "c=" base64(cbind-input) cbind-input = (("p=" cb-name) / "n" / "y") "," [ authzid ] "," [ cbind-data ] where cbind-data has to be absent by definition as dovecot does not support channel binding so no "p=" is possible and thus no cbind-data. This means c=bixhPXVzZXI decodes into. n,a=user, And this is where it gets strange. The dovecot code section which throws the error, implements the following: https://github.com/dovecot/core/blob/a5209c83c3a82386c94d466eec5fea394973e8… cbind_input = t_strconcat(request->gs2_cbind_flag, ",,", NULL); str = t_str_new(MAX_BASE64_ENCODED_SIZE(strlen(cbind_input))); str_append(str, "c="); base64_encode(cbind_input, strlen(cbind_input), str); if (strcmp(fields[0], str_c(str)) != 0) { *error_r = "Invalid channel binding data"; return FALSE; } As you can see it uses the bind flag which was saved to the request. But instead of the authzid, it uses always an hardcoded empty string. Thus cbind-input is "n,," instead of "n,a=user," and results in the request being rejected with an "Invalid channel binding data". Which is on the one hand a funny message because dovecot does not support channel binding at all, as describe in https://github.com/dovecot/core/blob/a5209c83c3a82386c94d466eec5fea394973e8… but it also on the other hand somehow correct because cbind-input string does not match. Which is an illegal state during channel binding negotiation which should not happen. As said previously, it looks to me like a server side bug. Or did I miss something special case in the RFC? Kind Regards Thomas Schmid

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LDAP Help
by Günther J. Niederwimmer 03 Dec '21

03 Dec '21

Hello Dovecot professionals, I have a working user authentication with LDAP, now I want to allow the users to use mailAterneteAddress for their account, unfortunately I can't find any filter settings for dovecot that this works? I just can't find the right settings for LDAP (FreeIPA). Does anyone of you have any hints or links so that I can get on with it. Somehow I don't understand how I can umconvigure the dovecot-ldap.conf.ext Thank you for your help. -- mit freundlichen Grüßen / best regards Günther J. Niederwimmer

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new bee needs starter docs
by Gene Heskett 03 Dec '21

03 Dec '21

Greetings all' Brand New today install of debian bullseye. I have looked at you doc pages, but don't see a good tut for a newbie to use for setting it up the first time ever. I have version 2.3.13 (89f716dc2) from the debian bullseye distro. What I want is to pull from my ISP account, which is also running dovecot, to a local mailfile. Or I can do that with fetchmail, its been doing that for a decade already. Its currently using procmail to run stuff thru spamassassin and clamd depositing the survivors into a /var/mail/mailfile, which the older tde kmail then pulled and sorted into folders holding maildirs. But I can't get tde to install on bullseye. Kudo's for any help you can supply. Cheers, Gene

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execve(/usr/bin/sieve-test) failed: Argument list too long
by Patrick Cernko 03 Dec '21

03 Dec '21

Hi Dovecot developers, while debugging the above error message from sieve-test, I found out, that the content of directive ssl_ca is added as env var SSL_CA by doveconf on execve and sieve-test now uses doveconf. In our setup, ssl_ca is set to ssl_ca = </etc/ssl/certs/ca-certificates.crt on our director servers. We have backend servers with certificates signed by two different CAs and to avoid problems if a backend switches to a different CA, I decided to allow all "known" CAs. The corresponding env var SSL_CA has more than 230500 bytes, which causes execve to fail with error E2BIG. I found a workaround for the problem by setting ssl_ca = </etc/dovecot/backendCAs.pem Where this file contains only the two CAs used atm. However I would like to request a fix for this issue as others might also want to have all "known" CAs set for dovecot director backend connections. Best, -- Patrick Cernko <pcernko(a)mpi-klsb.mpg.de> +49 681 9325 5815 Joint Administration: Information Services and Technology Max-Planck-Institute fuer Informatik & Softwaresysteme

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DoveCot Virtual Mailboxes With MySql
by postfix＠aecperformance.com 03 Dec '21

03 Dec '21

PLEASE HELP - Dovecot Virtual Mailboxes Using MySql I have a thread detailing my problem with config here: https://ubuntuforums.org/showthread.php?t=2469564 VPS Ubuntu 20.04 postfix 3.4.13 and dovecot 2.3.7.2 I've got multiple domains each having multiple emails. I'm using Virtual Mailboxes and MySql. My first domain: softlinksys.com has an MX pointing at mail.softlinksys.com. You can easily verify it. The IP address shown on https://mxtoolbox.com/ is: 194.163.45.150 <https://mxtoolbox.com/SuperTool.aspx?action=mx%3asoftlinksys.com&run=toolpa ge> which is my VPS IP address. I have a virtual_domains record in mysql with softlinksys.com as the domain. I have an email address mailadm(a)softlinksys.com <mailto:mailadm@softlinksys.com> in virtual_users in mysql. In the client app: Thunderbird the imap server is set as mail.softlinksys.com I can't connect that user to the mailbox from Thunderbird. If I change the imap server in Thunderbird to softlinksys.com the mailbox will connect I can't send an email to mailadm(a)softlinksys.com <mailto:mailadm@softlinksys.com> . It bounces whether MySql virtual_domains.name = softlinksys.com or mail.softlinksys.com. I've tried both softlinksys.com and mail.softlinksys.com in the database record and in Thunderbird. I just can't make it work. PLEASE HELP! How can I resolve this problem? Kristy Atkins ViviData SaaS

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Requested CRAM-MD5 scheme, but we have only CRYPT
by absolutely_free＠libero.it 02 Dec '21

02 Dec '21

Hi, I use dovecot-2.3.15 with MySQL backend for authentication. I just converted cleartext credentials in SSHA512. Authentication (POP3/IMAP/Roundcube webmail) is working fine. I got a few users complianing about login issues with Thunderbird. Logs show this: Dec 1 16:34:52 mailserver dovecot[72554] auth-worker(72559): conn unix:auth-worker (uid=143): auth-worker<5294>: sql(user(a)domain.net,xx.yy.ww.zz,<g+jCZhfS/N1dKskw>): Requested CRAM-MD5 scheme, but we have only CRYPT I don't understand this error. It seems I still support CRAM-MD5: telnet localhost 143 Trying 127.0.0.1... Connected to localhost. Escape character is '^]'. * OK [CAPABILITY IMAP4rev1 SASL-IR LOGIN-REFERRALS ID ENABLE IDLE LITERAL+ STARTTLS AUTH=PLAIN AUTH=LOGIN AUTH=DIGEST-MD5 AUTH=CRAM-MD5] Dovecot ready. This is my conf: doveconf -n # 2.3.15 (0503334ab1): /usr/local/etc/dovecot/dovecot.conf # OS: FreeBSD 13.0-RELEASE-p4 amd64 zfs # Hostname: server.domain.net doveconf: Warning: please set ssl_dh=</usr/local/etc/dovecot/dh.pem doveconf: Warning: You can generate it with: dd if=/var/db/dovecot/ssl-parameters.dat bs=1 skip=88 | openssl dhparam -inform der > /usr/local/etc/dovecot/dh.pem auth_debug = yes auth_mechanisms = plain login digest-md5 cram-md5 auth_verbose = yes default_client_limit = 2000 default_process_limit = 500 default_vsz_limit = 512 M disable_plaintext_auth = no first_valid_gid = 125 first_valid_uid = 125 imap_id_log = * mail_gid = 1003 mail_location = maildir:/mail/domains mail_privileged_group = postfix mail_uid = 1003 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 { args = /usr/local/etc/dovecot/dovecot-sql-crypt.conf.ext driver = sql } service auth { unix_listener /var/spool/postfix/private/auth { group = postfix mode = 0666 user = postfix } unix_listener auth-userdb { group = postfix mode = 0600 user = postfix } } service imap { process_limit = 1024 } service lmtp { unix_listener /var/spool/postfix/private/dovecot-lmtp { group = postfix mode = 0600 user = postfix } } ssl_cert = </etc/ssl/wildcard.domain.net_bundle.crt ssl_dh = # hidden, use -P to show it ssl_key = # hidden, use -P to show it userdb { args = /usr/local/etc/dovecot/dovecot-sql-crypt.conf.ext driver = sql } protocol imap { mail_max_userip_connections = 100 } this is my dovecot-sql-crypt.conf.ext: # cat /usr/local/etc/dovecot/dovecot-sql-crypt.conf.ext driver=mysql default_pass_scheme=CRYPT connect= host=db.domain.net port=3306 dbname=mail user=user password=xxxxxxxxxxxxxxxxxxxx #password_query = SELECT case when crypt is not null then crypt else password end as password FROM `mailbox` WHERE username='%u' AND suspended='N' password_query = SELECT case when crypt is not null then crypt else password_crypt end as password FROM `mailbox` WHERE username='%u' AND suspended='N' user_query = SELECT concat('maildir:',home) as mail, 125 AS uid, 125 AS gid FROM mailbox WHERE username='%u' AND suspended='N' Thank you

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Strategies for protecting IMAP (e.g. MFA)
by Tyler Montney 01 Dec '21

01 Dec '21

With the world of ransomware as it is today (aka attacks seem more vicious and commonplace), anything I expose to WAN must have additional protection. I've seen a few posts to this list on it. The only thing that helped was that Dovecot supports OAuth. Through OAuth I figure I could implement MFA. However, I'd have to host my own identity server. From there, Thunderbird supports OAuth so that should work. Since this is getting increasingly complicated, I wanted to ask before going further. What do you all do? Any recommendations?

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Downloading mailbox from replica server
by Claudio Corvino 01 Dec '21

01 Dec '21

Hi, I have two IMAP/LMTP Dovecot server in replica (version 2.3.4.1) both connected through an IPsec tunnel, I use LDAP/AD for /userdb, /all seems to be working. I have a question: if I switch my Thunderbird/Outlook client to use the other server I have to download again all the emails, about 10 GB. Is there any way to avoid this? Do I have to download again all the folders every time I switch from node A to node B on my client? Thanks! Regards

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Strange errors with Dovecot replication
by Claudio Corvino 01 Dec '21

01 Dec '21

Hi, I have two IMAP/LMTP Dovecot server in replica (version 2.3.4.1) for testing purposes, both connected through an IPsec tunnel, I use LDAP/AD for /userdb, /all seems to work fine except for these errors present in logs every day: NODE A: /doveadm: Error: sieve: file storage: utime(/var/www/html/ooo/its-test) failed: Operation not permitted: 28 Time(s) dsync-local(its-test)<TxExKuQgeWHlTAAA045Smw>: Error: read(xxx) failed: Connection reset by peer (last sent=mailbox_delete, last recv=handshake): 1 Time(s) dsync-local(its-test)<fXcyHCd3eWGHXwAA045Smw>: Error: sieve: file storage: utime(/var/www/html/ooo/its-test) failed: Operation not permitted: 2 Time(s) dsync-local(its-test)<fZ2LISh3eWGOXwAA045Smw>: Error: read(xxx) failed: Connection reset by peer (last sent=mailbox_delete, last recv=handshake): 1 Time(s) dsync-local(its-test2)<PqNdGCd3eWGGXwAA045Smw>: Error: read(xxx) failed: Connection reset by peer (last sent=mailbox_delete, last recv=handshake): 1 Time(s)/ NODE B: /doveadm: Error: Couldn't lock /mnt/mail-storage-dev/its-test/.dovecot-sync.lock: fcntl(/mnt/mail-storage-dev/its-test/.dovecot-sync.lock, write-lock, F_SETLKW) locking failed: Timed out after 30 seconds: 2 Time(s) doveadm: Error: Couldn't lock /mnt/mail-storage-dev/its-test2/.dovecot-sync.lock: fcntl(/mnt/mail-storage-dev/its-test2/.dovecot-sync.lock, write-lock, F_SETLKW) locking failed: Timed out after 30 seconds: 1 Time(s) doveadm: Error: sieve: file storage: utime(/var/www/html/ooo/its-test) failed: Operation not permitted: 28 Time(s) dsync-local(its-test)<QtV8HSh3eWHFDgAA/HgeEQ>: Error: sieve: file storage: utime(/var/www/html/ooo/its-test) failed: Operation not permitted: 2 Time(s)/ What I have to do? Do I have to worry about this or I can ignore it? Thanks Regards

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sieve - segmentation fault
by kjonca＠o2.pl 01 Dec '21

01 Dec '21

I tried to experiment with "index" extension and I found that, in case "0" sieve-filter segfaults. example code was: --8<---------------cut here---------------start------------->8--- if header :index 0 :last :regex "received" "some regex here" { fileinto "dedicated mailbox" ; } --8<---------------cut here---------------end--------------->8--- KJ -- http://stopstopnop.pl/stop_stopnop.pl_o_nas.html I dote on his very absence. -- William Shakespeare, "The Merchant of Venice"

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