Can't add a pam_unix module to any service.
After submitting the form, it reports this error:
"Failed to save module : Missing or invalid minimum password length"
Well of course it's missing... because the related fields are missing in the add pam_unix module form:
Minimum password length None
Maximum password length No limit
Prevent use of easy passwords? Yes No
They do show up when you are editing a existing pam_unix module though.