RADIUS attribute from rfc2866

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Acct-Authentic

This attribute MAY be included in an Accounting-Request to
      indicate how the user was authenticated, whether by RADIUS, the
      NAS itself, or another remote authentication protocol.  Users who
      are delivered service without being authenticated SHOULD NOT
      generate Accounting records.

   A summary of the Acct-Authentic attribute format is shown below.  The
   fields are transmitted from left to right.

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Type      |    Length     |             Value
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
              Value (cont)         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+Type

      45 for Acct-Authentic.

   Length

      6

   Value

      The Value field is four octets.

      1      RADIUS
      2      Local
      3      Remote

        FreeRADIUS Vendor-Specific dictionary values:

                    1 - RADIUS 
                    2 - Local 
                    3 - Remote 
                    4 - Diameter 
            

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