[Dovecot] Dovecot hanging up with many defunct processes

[Troy Engel]

Mayank Joshi wrote:
> 
>      passdb:
>          driver: pam
>      userdb:
>          driver: passwd
> 4) Dovecot's PAM file (/etc/pam.d/dovecot)
>      #%PAM-1.0
>      auth    required pam_ldap.so
>      account required pam_ldap.so
>      session required pam_mkhomedir.so skel=/etc/skel umask=0077
>      session required pam_ldap.so

Our situation is similar (but not exact) to yours - I'm authenticating 
against LDAP though and not AD2003. Perhaps one of these settings I use 
may help:

dovecot.conf:
   login_process_per_connection: no

   auth default:
     cache_size: 4096
     cache_ttl: 7200
     passdb:
       driver: pam
       args: cache_key=%u dovecot
     userdb:
       driver: passwd
       args: blocking=yes

The blocking=yes in the userdb might be the first thing you try, see 
these wiki pages for the reasons I have it like this:

   http://wiki.dovecot.org/UserDatabase/NSS
   http://wiki.dovecot.org/AuthDatabase/Passwd

Additionally my pam.d dovecot uses the system stack, which *then* uses 
nss_ldap on it's own; I don't specifically bind pam_ldap into the 
dovecot pam.d file:

   # cat /etc/pam.d/dovecot
   #%PAM-1.0
   auth       required     pam_nologin.so
   auth       required     pam_stack.so service=system-auth
   account    required     pam_stack.so service=system-auth
   session    required     pam_stack.so service=system-auth

In this case the file /etc/nsswitch.conf is controlling my 
authentication mechanism (LDAP), and the pam_ldap.so stack entry is 
located in /etc/pam.d/system-auth (these are all Red Hat defaults out of 
the box).

Hope some of this helps,
-te

-- 
Troy Engel | Systems Engineer
Fluid, Inc | http://www.fluid.com