/etc/freeradius/3.0/mods-available/ is in freeradius-config 3.0.12+dfsg-5+deb9u1.
This file is owned by root:root, with mode 0o755.
..
/etc/freeradius/3.0/mods-available/README.rst
/etc/freeradius/3.0/mods-available/abfab_psk_sql
/etc/freeradius/3.0/mods-available/always
/etc/freeradius/3.0/mods-available/attr_filter
/etc/freeradius/3.0/mods-available/cache
/etc/freeradius/3.0/mods-available/cache_eap
/etc/freeradius/3.0/mods-available/chap
/etc/freeradius/3.0/mods-available/couchbase
/etc/freeradius/3.0/mods-available/counter
/etc/freeradius/3.0/mods-available/cui
/etc/freeradius/3.0/mods-available/date
/etc/freeradius/3.0/mods-available/detail
/etc/freeradius/3.0/mods-available/detail.example.com
/etc/freeradius/3.0/mods-available/detail.log
/etc/freeradius/3.0/mods-available/dhcp
/etc/freeradius/3.0/mods-available/dhcp_sqlippool
/etc/freeradius/3.0/mods-available/digest
/etc/freeradius/3.0/mods-available/dynamic_clients
/etc/freeradius/3.0/mods-available/eap
/etc/freeradius/3.0/mods-available/echo
/etc/freeradius/3.0/mods-available/etc_group
/etc/freeradius/3.0/mods-available/exec
/etc/freeradius/3.0/mods-available/expiration
/etc/freeradius/3.0/mods-available/expr
/etc/freeradius/3.0/mods-available/files
/etc/freeradius/3.0/mods-available/idn
/etc/freeradius/3.0/mods-available/inner-eap
/etc/freeradius/3.0/mods-available/ippool
/etc/freeradius/3.0/mods-available/krb5
/etc/freeradius/3.0/mods-available/ldap
/etc/freeradius/3.0/mods-available/linelog
/etc/freeradius/3.0/mods-available/logintime
/etc/freeradius/3.0/mods-available/mac2ip
/etc/freeradius/3.0/mods-available/mac2vlan
/etc/freeradius/3.0/mods-available/mschap
/etc/freeradius/3.0/mods-available/ntlm_auth
/etc/freeradius/3.0/mods-available/opendirectory
/etc/freeradius/3.0/mods-available/otp
/etc/freeradius/3.0/mods-available/pam
/etc/freeradius/3.0/mods-available/pap
/etc/freeradius/3.0/mods-available/passwd
/etc/freeradius/3.0/mods-available/perl
/etc/freeradius/3.0/mods-available/preprocess
/etc/freeradius/3.0/mods-available/python
/etc/freeradius/3.0/mods-available/radutmp
/etc/freeradius/3.0/mods-available/realm
/etc/freeradius/3.0/mods-available/redis
/etc/freeradius/3.0/mods-available/rediswho
/etc/freeradius/3.0/mods-available/replicate
/etc/freeradius/3.0/mods-available/rest
/etc/freeradius/3.0/mods-available/smbpasswd
/etc/freeradius/3.0/mods-available/smsotp
/etc/freeradius/3.0/mods-available/soh
/etc/freeradius/3.0/mods-available/sometimes
/etc/freeradius/3.0/mods-available/sql
/etc/freeradius/3.0/mods-available/sqlcounter
/etc/freeradius/3.0/mods-available/sqlippool
/etc/freeradius/3.0/mods-available/sradutmp
/etc/freeradius/3.0/mods-available/unbound
/etc/freeradius/3.0/mods-available/unix
/etc/freeradius/3.0/mods-available/unpack
/etc/freeradius/3.0/mods-available/utf8
/etc/freeradius/3.0/mods-available/wimax
/etc/freeradius/3.0/mods-available/yubikey