/etc/freeradius/dictionary is in freeradius-common 2.1.12+dfsg-1.2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 | #
#	This is the master dictionary file, which references the
#	pre-defined dictionary files included with the server.
#
#	Any new/changed attributes MUST be placed in this file, as
#	the pre-defined dictionaries SHOULD NOT be edited.
#
#	$Id$
#
#
#  The DHCP dictionary is used only when the server is built with
#  "configure --with-dhcp".  It is not (and should not) be used in
#  other situations.  If you are running just a RADIUS server, this
#  line can be deleted.  If you are using DHCP, the following line
#  should be uncommented.
#
#  Ideally, the "configure" process should automatically enable this
#  dictionary, but we don't yet do that.
#
#$INCLUDE	/usr/dictionary.dhcp
#
#	The filename given here should be an absolute path. 
#
$INCLUDE	/usr/share/freeradius/dictionary
#
#	Place additional attributes or $INCLUDEs here.  They will
#	over-ride the definitions in the pre-defined dictionaries.
#
#	See the 'man' page for 'dictionary' for information on
#	the format of the dictionary files.
#
#	If you want to add entries to the dictionary file,
#	which are NOT going to be placed in a RADIUS packet,
#	add them here.  The numbers you pick should be between
#	3000 and 4000.
#
#ATTRIBUTE	My-Local-String		3000	string
#ATTRIBUTE	My-Local-IPAddr		3001	ipaddr
#ATTRIBUTE	My-Local-Integer	3002	integer
 |