Hi,

We have growing imap-login processes until we reach the max processes.

This occurs when a particular user have a login error due to our LDAP misconfiguration:

Mar  4 14:59:33 hera dovecot[2226963]: auth: Error: plain(john.doe,XX.XX.XX.XX,<13C0eBP2354lqXpO>): user not found from any userdbs Mar  4 14:59:33 hera dovecot[2226963]: imap: Error: auth-master: login: request [1001652225]: Login auth request failed: Authenticated user not found from userdb, auth lookup id=1001652225 (auth connected 2 msecs ago, request took 1 msecs, client-pid=2235348 client-id=1) Mar  4 14:59:33 hera dovecot[2226963]: imap-login: Internal login failure (pid=2235348 id=1): user=, method=PLAIN, rip=XX.XX.XX.XX, lip=18 5.233.100.1, mpid=2235359, TLS, session=<13C0eBP2354lqXpO>

The origin of is issue is when passdb finds the user and userdb not. The result is imap-login processes with no timeout growing until we reach the max processes.

• OS version

Debian stable - Bullseye

• Dovecot version

dpkg -l |grep dovecot ii  dovecot-antispam                    2.0+20171229-1+b7 amd64        Dovecot plugins for training spam filters ii  dovecot-common                      1:2.1.7-7+deb7u1 all          Transitional package for dovecot ii  dovecot-core                        1:2.3.13+dfsg1-2+deb11u1 amd64        secure POP3/IMAP server - core files ii  dovecot-core-dbgsym                 1:2.3.13+dfsg1-2+deb11u1 amd64        debug symbols for dovecot-core ii  dovecot-imapd                       1:2.3.13+dfsg1-2+deb11u1 amd64        secure POP3/IMAP server - IMAP daemon ii  dovecot-imapd-dbgsym                1:2.3.13+dfsg1-2+deb11u1 amd64        debug symbols for dovecot-imapd ii  dovecot-ldap                        1:2.3.13+dfsg1-2+deb11u1 amd64        secure POP3/IMAP server - LDAP support ii  dovecot-managesieved                1:2.3.13+dfsg1-2+deb11u1 amd64        secure POP3/IMAP server - ManageSieve server ii  dovecot-mysql                       1:2.3.13+dfsg1-2+deb11u1 amd64        secure POP3/IMAP server - MySQL support ii  dovecot-pop3d                       1:2.3.13+dfsg1-2+deb11u1 amd64        secure POP3/IMAP server - POP3 daemon ii  dovecot-sieve                       1:2.3.13+dfsg1-2+deb11u1 amd64        secure POP3/IMAP server - Sieve filters support

• doveconf -n

# 2.3.13 (89f716dc2): /etc/dovecot/dovecot.conf # Pigeonhole version 0.5.13 (cdd19fe3) doveconf: Warning: service auth { client_limit=1000 } is lower than required under max. load (4096) doveconf: Warning: service anvil { client_limit=1000 } is lower than required under max. load (4099) # OS: Linux 5.10.0-21-cloud-amd64 x86_64 Debian 11.6 ext4 # Hostname: XXX auth_mechanisms = plain login default_process_limit = 1024 first_valid_gid = 8 first_valid_uid = 109 last_valid_gid = 8 last_valid_uid = 109 login_greeting = XXX listening. mail_access_groups = mail mail_gid = 8 mail_location = maildir:/srv/vmail/%d/%n mail_privileged_group = mail mail_uid = 109 managesieve_notify_capability = mailto managesieve_sieve_capability = fileinto reject envelope encoded-character vacation subaddress comparator-i;ascii-numeric relational regex imap4flags copy i nclude variables body enotify environment mailbox date index ihave duplicate mime foreverypart extracttext imapflags notify imapsieve vnd.dovecot.imapsieve vnd.dovecot.filter 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 = /etc/dovecot/dovecot-ldap.conf driver = ldap } passdb { args = /etc/dovecot/dovecot-ldap-girondix.conf driver = ldap } passdb { args = /etc/dovecot/dovecot-oauth2.conf.ext driver = oauth2 mechanisms = xoauth2 oauthbearer } plugin { quota_rule = *:storage=100M quota_rule2 = Trash:storage=10%% recipient_delimiter = + sieve = /srv/vmail/%d/%n/dovecot.sieve sieve_default = /var/lib/dovecot/sieve/default.sieve sieve_dir = /srv/vmail/%d/%n/sieve sieve_extensions = +notify +imapflags +vnd.dovecot.filter sieve_filter_bin_dir = /usr/lib/dovecot/sieve-filter sieve_global_extensions = +vnd.dovecot.pipe sieve_max_script_size = 1M sieve_pipe_bin_dir = /etc/dovecot/sieve sieve_pipe_socket_dir = sieve-pipe sieve_plugins = sieve_imapsieve sieve_extprograms sieve_redirect_envelope_from = orig_recipient } protocols = imap pop3 sieve service auth { unix_listener /var/spool/postfix/private/auth { group = mail mode = 0600 user = postfix } unix_listener auth-master { group = mail mode = 0660 user = vmail } unix_listener auth-userdb { group = mail mode = 0600 user = vmail } } service imap-login { inet_listener imap { port = 0 } } service imap { vsz_limit = 1 G } service lmtp { executable = lmtp -L process_min_avail = 2 } service pop3-login { inet_listener pop3 { port = 0 } } ssl_cert =