Dovecot (with Postfix) configuration has connection refused when accessing auth-userdb

Question

...this was a hard one to describe in a title. This description should highlight the problem.

Context

• I was following the Workaround.org tutorial to install a postfix, dovecot (plus some additional plugins) stack.
• Running on a Ubuntu 12.04 machine (VM with Vagrant/Chef)
• Dovecot v2.0.19
• Postfix v2.9.6

Conf. Files

10-master

....
service auth {    
unix_listener auth-userdb {
  mode = 0644
  user = vmail
  group = vmail
}
...

Edit - additional config info(some overlap)

service auth {
# auth_socket_path points to this userdb socket by default. It's typically
# used by dovecot-lda, doveadm, possibly imap process, etc. Its default
# permissions make it readable only by root, but you may need to relax these
# permissions. Users that have access to this socket are able to get a list
# of all usernames and get results of everyone's userdb lookups.
unix_listener auth-userdb {
  mode = 0644
  user = vmail
  group = vmail
}

# Postfix smtp-auth
unix_listener /var/spool/postfix/private/auth {
  mode = 0660
  user = postfix
  group = postfix
}

# Auth process is run as this user.
#user = $default_internal_user
user = dovecot
}

auth-sql

userdb {
  driver = static
  args = uid=vmail gid=vmail home=/var/vmail/%d/%n allow_all_users=yes
}

ls -la /var/run/dovecot/auth-userdb

srw-r--r-- 1 vmail vmail 0 Jun 20 13:04 /var/run/dovecot/auth-userdb

Postfix master.cf

dovecot    unix  -      n       n       -       -       pipe
   flags=DRhu user=vmail:vmail argv=/usr/lib/dovecot/dovecot-lda -d ${recipient}

Problem

I have followed the tutorial pretty closely, changing only some minor things. I arrived at the "Testing mail delivery" and ran echo test | mail [email protected]

The mail didn't arrive since find /var/vmail didn't show anything.

In the server syslog the following errors are present:

postfix/pickup[16842]: 019023A06AB: uid=1000 from=<vagrant>
postfix/cleanup[19542]: 019023A06AB: message-id=   <20130620140358.019023A06AB@mail-server-berkshelf>
postfix/qmgr[16843]: 019023A06AB: from=<[email protected]>, size=382, nrcpt=1 (queue active)
dovecot: lda: Debug: Loading modules from directory: /usr/lib/dovecot/modules
dovecot: lda: Debug: Module loaded: /usr/lib/dovecot/modules/lib90_sieve_plugin.so
dovecot: lda: Error: userdb lookup: connect(/var/run/dovecot/auth-userdb) failed: Connection refused
dovecot: lda: Fatal: Internal error occurred. Refer to server log for more information.
postfix/pipe[19545]: 019023A06AB: to=<[email protected]>, relay=dovecot, delay=1.2, delays=0.04/0.01/0/1.1, dsn=4.3.0, status=deferred (temporary failure)

The "connection refused" error should be the error I'm attacking, right? I've searched in a lot of places to understand what is going on here, but haven't come across anything helpful.

Can anyone provide any leads or insights? A solution would be great, but I'm happy to accept some new ideas to try out.

Answer 1

The connection refused error is indeed the problem. Connection refused on unix sockets is not terribly intuitive, but it indicates that there is nothing listening on the socket (typically, the process is dead, or the file given as the address wasn't a socket at all). This should never be a permissions issue, unless dovecot is unable to open the socket for listening due to permissions.

Try stopping dovecot and postfix, removing the socket file at /var/run/dovecot/auth-userdb, and starting postfix and dovecot again (ensuring the user dovecot is running as has permissions on /var/run/dovecot). Usually this will fix this type of issue.

Netstat will also display unix domain sockets. Check its output (use netstat -nvlap | less and search for the path or for dovecot) to ensure dovecot is listening.