I'm having great difficulty debugging this problem.. I'm having intermittant problems connecting to dovecot. This started a couple of days ago following an apt-get update on the server.

I'm running Ubuntu 14.04, dovecot 2.2.9. Here's my dovecot -n

# 2.2.9: /etc/dovecot/dovecot.conf # OS: Linux 3.19.0-59-generic x86_64 Ubuntu 14.04.4 LTS auth_mechanisms = plain login mail_location = maildir:~/Maildir 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 } plugin { sieve_dir = ~/sieve } protocols = imap service auth { unix_listener /var/spool/postfix/private/auth { mode = 0666 } user = $default_internal_user } ssl = required ssl_cert = </etc/dovecot/box.neuralnet.org.uk_crt.pem ssl_key = </etc/dovecot/box.neuralnet.org.uk_key.pem ssl_protocols = !SSLv2 !SSLv3 userdb { driver = passwd }

Pretty standard stuff. In addition disable_plaintext_auth = yes is set in 10-auth.conf

This showed up in the mail.err after the reboot;

May 17 09:04:51 server dovecot: imap-login: Error: read(anvil) failed: EOF May 17 09:04:51 server dovecot: auth: Error: read(anvil-auth-penalty) failed: EOF May 17 09:04:51 server dovecot: auth: Error: net_connect_unix(anvil-auth-penalty) failed: Permission denied

At that point

The following commands were run on the server a few minutes apart with no changes made in the interim;

username@box /etc/dovecot $ doveadm user username field valueuserdb lookup: user username doesn't exist

username@box /etc/dovecot $ doveadm user username field value uid 1000 gid 1000 home /home/username mail maildir:~/Maildir system_groups_user username

so, passdb wasn't accessible, but now it is ?

Imap logins are showing in mail.log as failing, but thunderbird is currently connected;

May 18 12:00:58 box dovecot: imap-login: Disconnected (auth failed, 3 attempts in 19 secs): user=<username>, method=PLAIN, rip=10.0.0.3, lip=10.0.0.99, TLS, session=<********> May 18 12:08:27 box dovecot: imap-login: Disconnected (auth failed, 3 attempts in 20 secs): user=<username>, method=PLAIN, rip=10.0.0.3, lip=10.0.0.99, TLS, session=<********> May 18 12:08:50 box dovecot: imap-login: Disconnected (auth failed, 3 attempts in 12 secs): user=<username>, method=PLAIN, rip=10.0.0.3, lip=10.0.0.99, TLS, session=<********>

do I conclude that method=plain is failing, whereas method=login succeeds ? I tried setting auth_debug_password=yes and get the following;

May 18 12:26:42 box dovecot: auth: Debug: client in: CONT#0111#011A********== (previous base64 data may contain sensitive data) May 18 12:26:42 box dovecot: auth-worker(12214): Debug: Loading modules from directory: /usr/lib/dovecot/modules/auth May 18 12:26:42 box dovecot: auth-worker(12214): Debug: pam(expert,10.0.0.3): lookup service=dovecot May 18 12:26:42 box dovecot: auth-worker(12214): Debug: pam(expert,10.0.0.3): #1/1 style=1 msg=Password: May 18 12:26:42 box dovecot: auth-worker(12211): pam(username,10.0.0.3): pam_authenticate() failed: Authentication failure (password mismatch?) (given password: ******) May 18 12:26:44 box dovecot: auth: Debug: client passdb out: FAIL#0112#011user=username

Any assistance debugging this further is greatly recieved! Thanks.