Thanks for the syntax.
Still not working (tried 3 times, double-checking the password each time and trying cut/paste too) :
Code:
[zimbra@zimbra-oss ~]$ ldapmodify -x -h localhost -D "uid=zimbra,cn=admins,cn=zimbra" -W
Enter LDAP Password:
ldap_bind: Can't contact LDAP server (-1)