Hi All,
 
Just in case it's helpful to anybody. This is how I implemented SSO witn NTLM authentication on SLES.
I know there is a howto about it on wiki but it was missing few bits in my case. 
  
1) Installed Apache2::AuthenNTLM module by running:
# perl -e shell -MCPAN
cpan[1]> install Apache2::AuthenNTLM
 
2) Edited /etc/apache2/httpd.conf and added
KeepAlive On
 
3) Edited /otrs Location in /etc/apache2/conf.d/otrs.conf and added
  PerlAuthenHandler Apache2::AuthenNTLM
  AuthType ntlm,basic
  AuthName Basic
  require valid-user
  PerlAddVar ntdomain "DOMAIN dc1 dc2"
  PerlSetVar defaultdomain DOMAIN
  PerlSetVar ntlmdebug 0

where:
DOMAIN - name of our NT domain (just the first bit of the name, before the first dot)
dc1, dc2 - names of our domain controllers (just the hostname, without domain bit). Make sure you can ping those names
 
 4) Edited Config.pm file and added
$Self->{'AuthModule'} = 'Kernel::System::Auth::HTTPBasicAuth';
$Self->{'AuthModule::HTTPBasicAuth::Replace'} = 'domain\\';
 
where
domain - name of our domain again
 
5) Added to /etc/hosts
IP_ADDR    DOMAIN DOMAIN.CO.UK
 
where
IP_ADDR is the IP address of my primary domain controller
 
6) And the final bit (that took me few hours to work out btw) is to add mod_perl to APACHE_MODULES in /etc/sysconfig/apache2
 
7) Restart apache and otrs
 
Once this is all done, I'm logged in automatically when going to OTRS login page.
The only thing is that it only works when:
- I'm using Internet Explorer and the site is in 'Local Intranet' zone
- I'm on the local company network, ie. it doesn't work over vpn so it's not perfect.
 
--
Kind Regards,
Robert