435 unable to authenticate at present authentication socket connection error. How to fix?

Question

Debian

I am transferring a mailer from bsd to debian, I ran into a problem:

2016-02-18 12:37:32 no host name found for IP address 192.168.1.50
2016-02-18 12:37:32 dovecot_login authenticator failed for (Roma) [192.168.1.50] I=[192.168.1.11]:25: 435 Unable to authenticate at present: authentication socket connection error

I can’t understand what is the reason, but during the transfer I had to redo the sql queries to the database, because For some reason he got the wrong path to the folders. In general, authorization through dovecot does not work.
currently:
dovecot-sql.conf.ext:

driver = mysql
connect = host=localhost dbname=mail user=mail password=password
default_pass_scheme = CRAM-MD5
password_query = SELECT `username` as `user`, `password` FROM `mailbox` WHERE `username` = '%[email protected]%d' AND `active`='1'
user_query = SELECT CONCAT('/var/mail/','%d','/','%[email protected]%d','/') \
AS `home`, 8 AS `uid`, 8 AS `gid`, concat('dict:storage=', \
CAST(ROUND(quota / 1024) AS CHAR), '::proxy::sqlquota') \
AS quota, CONCAT('*:storage=', CAST(quota AS CHAR), 'B') AS quota_rule \
FROM `mailbox` WHERE `username` = '%[email protected]%d' AND `active`='1'

exim config snippet:

begin authenticators

dovecot_login:
driver = dovecot
public_name = LOGIN
server_socket = /var/run/dovecot/auth-client
server_set_id = $auth1

dovecot_plain:
driver = dovecot
public_name = PLAIN
server_socket = /var/run/dovecot/auth-client
server_set_id = $auth1

dovecot_cram_md5:
driver = dovecot
public_name = CRAM-MD5
server_socket = /var/run/dovecot/auth-client
server_set_id = $auth1

dovecot log:

Feb 18 12:50:36 master: Info: Dovecot v2.2.13 starting up for imap, pop3, imap, sieve, pop3, sieve (core dumps disabled)
Feb 18 12:50:36 master: Warning: /mnt is no longer mounted. See http://wiki2.dovecot.org/Mountpoints
Feb 18 12:50:36 auth: Debug: Loading modules from directory: /usr/lib/dovecot/modules/auth
Feb 18 12:50:36 auth: Debug: Module loaded: /usr/lib/dovecot/modules/auth/libdriver_mysql.so
Feb 18 12:50:36 auth: Debug: Read auth token secret from /var/run/dovecot//auth-token-secret.dat
Feb 18 12:50:36 auth: Debug: auth client connected (pid=12930)
Feb 18 12:50:36 auth: Debug: auth client connected (pid=12935)
Feb 18 12:50:36 auth: Debug: auth client connected (pid=12934)
Feb 18 12:50:45 auth: Debug: auth client connected (pid=12967)
Feb 18 12:50:45 auth: Debug: client in: AUTH    1       PLAIN   service=pop3    session=R3DlTAgsqwDAqAEy        lip=192.168.1.11        rip=192.168.1.50        lport=110       rport=57259     resp=<hidden>
Feb 18 12:50:45 auth-worker(12968): Debug: Loading modules from directory: /usr/lib/dovecot/modules/auth
Feb 18 12:50:45 auth-worker(12968): Debug: Module loaded: /usr/lib/dovecot/modules/auth/libdriver_mysql.so
Feb 18 12:50:45 auth-worker(12968): Debug: sql([email protected],192.168.1.50): query: SELECT `username` as `user`, `password` FROM `mailbox` WHERE `username` = '[email protected]' AND `active`='1'
Feb 18 12:50:45 auth: Debug: client passdb out: OK      1       [email protected]
Feb 18 12:50:45 auth: Debug: master in: REQUEST 1937244161      12967   1       e6d5c321b369770d5779012b84925afa        session_pid=12970
Feb 18 12:50:45 auth-worker(12968): Debug: sql([email protected],192.168.1.50): SELECT CONCAT('/var/mail/','mydomain.ru','/','[email protected]','/') AS `home`, 8 AS `uid`, 8 AS `gid`, concat('dict:storage=', CAST(ROUND(quota / 1024) AS CHAR), '::proxy::sqlquota') AS quota, CONCAT('*:storage=', CAST(quota AS CHAR), 'B') AS quota_rule FROM `mailbox` WHERE `username` = '[email protected]' AND `active`='1'
Feb 18 12:50:45 auth: Debug: master userdb out: USER    1937244161      [email protected]       home=/var/mail/mydomain.ru/[email protected]/    uid=8    gid=8   quota=dict:storage=0::proxy::sqlquota   quota_rule=*:storage=0B
Feb 18 12:50:45 pop3-login: Info: Login: user=<[email protected]>, method=PLAIN, rip=192.168.1.50, lip=192.168.1.11, mpid=12970, session=<R3DlTAgsqwDAqAEy>
Feb 18 12:50:45 pop3([email protected]): Info: Disconnected: Logged out top=0/0, retr=0/0, del=0/0, size=0

Answer 1

Add to 10-master.conf:

service auth {
...
  unix_listener auth-client {
    mode = 0666
    user = mail
  }
...
}