After your running freeradius -X and found the error
Detail Error:
radiusd: #### Opening IP addresses and Ports ####
listen {
type = "auth"
ipaddr = 127.0.0.1
port = 18120
Failed binding to auth address 127.0.0.1 port 18120 bound to server inner-tunnel: Address already in use
/etc/freeradius/3.0/sites-enabled/inner-tunnel[33]: Error binding to port for 127.0.0.1 port 18120
Error is Failed binding to auth address 127.0.0.1 port 18120 bound to server inner-tunnel: Address already in use
Troubleshoot:
$ lsof -Pni:1812
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
freeradiu 1853 freerad 30u IPv4 32658 0t0 UDP *:1812
freeradiu 1853 freerad 32u IPv6 32660 0t0 UDP *:1812
$ kill -9 1853
$ freeradius -X
OR
freeradius -X is debugging mode, if you freeradius running before your run this command. Please stop the service freeradius and run command.