mod_quotatab_radiusmod_quotatab submodule is contained in the
mod_quotatab_radius.c, part of the mod_quotatab
package and is not compiled by default.  See the mod_quotatab
documentation for installation
instructions.
This submodule provides the RADIUS-specific "driver" for retrieving quota limit table information from a RADIUS server.
Please contact TJ Saunders <tj at castaglia.org> with any questions, concerns, or suggestions regarding this module.
The mod_quotatab_radius module supports the "radius"
string for the source-type parameter of the
QuotaLimitTable
configuration directive.
The RADIUS attribute to be looked up should contain a comma-separated list of values, in the following order:
  per_session,limit_type,bytes_in_avail,bytes_out_avail,bytes_xfer_avail,
    files_in_avail,files_out_avail,files_xfer_avail
For example:
"false,hard,100,100,100,100,100,100"
An example proftpd.conf configuration might look like:
  <IfModule mod_quotatab.c>
    <IfModule mod_quotatab_radius.c>
      # Use a RADIUS-based limit table
      QuotaLimitTable radius:$(777:false,hard,100,100,100,100,100,100)
    </IfModule>
    # Use a file-based tally table
    QuotaTallyTable file:/usr/local/proftpd/ftpquota.tallytab
  </IfModule>
This assumes that you have defined your RADIUS quota attribute to have an ID
of 777, e.g.:
ATTRIBUTE FTP-Quota 777 string