Dovecot Authentication Timeout Problem

[jamesterror]

Hi,

Have been trying to hold off posting on the forum and find a solution myself but I'm struggling now.

We have been trying to resolve an issue this week that is occurring with Dovecot on IMAP connections regarding to timeout and problems by external email clients, I believe the error has been going on longer than a week though, I've only just switched my mail account from POP3 to IMAP.

In Outlook every 6 hours I am prompted for the passwords of my three email accounts on separate domains setup on our main web server. I've Googled / searched the cPanel forums but am still struggling to find an answer. I have increased authentication process under Mail Configuration on cPanel bit still the errors persist, here is the latest occurance taken from /var/log/maillog -

May 22 21:36:20 dovecot: IMAP([email protected]): Disconnected: Logged out bytes=63/550
May 22 21:36:22 dovecot: imap-login: Login: user=<[email protected]>, method=PLAIN, rip=81.*.*.*, lip=93.*.*.*
May 22 21:36:22 dovecot: imap-login: Login: user=<[email protected]>, method=PLAIN, rip=81.*.*.*, lip=93.*.*.*, TLS
May 22 21:36:23 dovecot: imap-login: Login: user=<[email protected]>, method=PLAIN, rip=81.*.*.*, lip=93.*.*.*
May 22 21:36:25 dovecot: imap-login: Login: user=<[email protected]>, method=PLAIN, rip=81.*.*.*, lip=93.*.*.*
May 22 21:36:25 dovecot: imap-login: Login: user=<[email protected]>, method=PLAIN, rip=81.*.*.*, lip=93.*.*.*, TLS
May 22 21:36:29 dovecot: imap-login: Login: user=<[email protected]>, method=PLAIN, rip=81.*.*.*, lip=93.*.*.*, TLS
May 22 21:36:46 dovecot: imap-login: Login: user=<[email protected]>, method=PLAIN, rip=81.*.*.*, lip=93.*.*.*, TLS
May 22 21:36:55 dovecot: imap-login: Login: user=<[email protected]>, method=PLAIN, rip=81.*.*.*, lip=93.*.*.*, TLS
May 22 21:36:55 dovecot: IMAP([email protected]): Disconnected: Logged out bytes=576/5346
May 22 21:36:56 dovecot: IMAP([email protected]): Disconnected: Logged out bytes=417/4461
May 22 21:36:57 dovecot: IMAP([email protected]): Disconnected: Logged out bytes=569/5231
May 22 21:36:57 dovecot: IMAP([email protected]): Disconnected: Logged out bytes=63/550

I also spotted the line below, and came across this thread - cpHulkd is up to date -

May 22 21:35:33 chocolate dovecot: imap-login: Login: user=<[email protected]>, method=PLAIN, rip=81.*.*.*, lip=93.*.*.*, TLS
May 22 21:35:45 chocolate dovecot: auth(default): cphulkd rejected registration attempt for dovecot with: -1

Any help would be greatly appreciated - Thanks in advance.

James

 

[cPanelMichael]

Hello

You may want to consider increasing the following options in "WHM Home » Service Configuration » Mailserver Configuration":

Maximum IMAP Connections Per IP
Maximum POP3 Connections per IP

If the issue persists, you can open a support ticket so we can take a closer look:

Submit A Ticket

Post the ticket number here if you decide to open a ticket so we can track the issue.

Thank you.

 

[jamesterror]

Hi Michael,

Thanks - they are currently at 10 each so I have increased them to 50 and see whether it helps.

Kind Regards,
James

 

[cPanelMichael]

Thanks - they are currently at 10 each so I have increased them to 50 and see whether it helps.

It's also possible there is a DOS attack on your mail server, and it's using up your available authentication daemons. Try using the following command to see if you notice any IP addresses with a high number of authentication failures:

# awk '/auth failed/ {for (i=1;i<=NF;i=i+1) if ($i~/rip/) print $i}' /var/log/maillog |sort|uniq -c|sort -n| tail

Thank you.