Starttls and SSL

[ldap@mm.st]

 I am in the process of moving our older existing openldap server
infrastructure that we use to authenticate multiple users to our Linux
infrastructure to use RH5 openldap 2.3 server.  The current ldap servers
support starttls and listen on 389 and 636.  We want to continue with
this setup.  While sniffing traffic using tcpdump and using various
ldapsearch options I noticed that if the client doesn't request starttls
or connect on 636 is is possible to grab a users ldap record and the
transmission is in clear text.  If I authenticate to the server using
the -W option to ldapsearch the record is sent with the SSHA encrypted
password.  Also in the in the tcpdump stream my password I use to
authenticate to the server is sent in clear text.  

I guess this behavior is expected since the server is listening on 389
and it is up to the client to initialize the starttls session, but I was
wondering if there was a way to force the server to only use starttls on
398 and not rely on the the client to set up starttls?   One option
would be to only have the server start on 636 and not have it listen on
389, but we would like to keep the same functionality if possible.  Am I
missing something obvious? The only option that I see as a possiblity is
the TLSVerifyClient { never | allow | try | demand } in slapd.conf. 
But, it's unclear to me if this will provide the desired effect.