dovecot - Aug 2010 - NTLM authentication does not work

Dear Experts,
I configured Samba, Kerberos, etc., can login to my CentOS using ADS account,
but missing something in my Dovecot config.

Windbind seems to work:
 [root at aCentOs2 dovecot]# wbinfo -a wAlex%pass
 plaintext password authentication succeeded
 challenge/response password authentication succeeded

Same is true for ntlm_auth helper:
 [root at aCentOs2 dovecot]# /usr/bin/ntlm_auth --username=wAlex --password=pass
 NT_STATUS_OK: Success (0x0)

But I couldn't get into Dovecot (with or without auth_use_winbind option):
. login wAlex pass
. NO [ALERT] Unsupported authentication mechanism.

Despite very verbose logging, there no clues there. Bellow's my dovecot -n
output:

# 2.0.0: /etc/dovecot/dovecot.conf
# OS: Linux 2.6.18-194.11.1.el5 i686 CentOS release 5.5 (Final)
auth_debug = yes
auth_debug_passwords = yes
auth_master_user_separator = *
auth_mechanisms = ntlm
auth_use_winbind = yes
auth_verbose = yes
auth_verbose_passwords = plain
debug_log_path = /var/log/Dovecot/dovecot_debug.log
disable_plaintext_auth = no
info_log_path = /var/log/Dovecot/dovecot_info.log
log_path = /var/log/Dovecot/dovecot.log
mail_location = maildir:~/Maildir
protocols = imap
ssl_cert = </etc/pki/dovecot/certs/dovecot.pem
ssl_key = </etc/pki/dovecot/private/dovecot.pem
userdb {
  args = uid=vmail gid=vmail home=/home/vmail/%u allow_all_users=yes
  driver = static
}

It might be irrelevant, but although the lines "auth_use_winbind =
yes" and "auth_winbind_helper_path = /usr/bin/ntlm_auth" are
close together in the config file, I cannot see the latter when run dovecot -n.

I am quite new to Dovecot and will appreciate any help.
Thanks, Alex.

On Mon, 2010-08-30 at 12:21 -0500, Alexander Cherniak
wrote:
> Windbind seems to work:
>  [root at aCentOs2 dovecot]# wbinfo -a wAlex%pass
>  plaintext password authentication succeeded
>  challenge/response password authentication succeeded
> 
> Same is true for ntlm_auth helper:
>  [root at aCentOs2 dovecot]# /usr/bin/ntlm_auth --username=wAlex
--password=pass
>  NT_STATUS_OK: Success (0x0)
I don't much know of NTLM, but..
> But I couldn't get into Dovecot (with or without auth_use_winbind
option):
> . login wAlex pass
> . NO [ALERT] Unsupported authentication mechanism.
..
> auth_mechanisms = ntlm
This error happens because you enabled NTLM mechanism, but disabled
PLAIN mechanism (LOGIN command uses PLAIN mechanism). If you want both
to work, use:

auth_mechanisms = plain ntlm

And note that winbind authentication only works for NTLM mechanism, not
for anything else. Maybe you need to figure out some other passdb to use
like LDAP or maybe some PAM plugin?..