communication safe ssh <-> NAS <-> FreeRADIUS ?

Hi, I authenticate on cisco equipments via ssh/telnet. There is no supplicant, so I don't understand in my case and i would like to know if the communication between my cisco equipment and my FreeRadius safe is. I have a secret shared between both. I understand that the communciation between freeradius and the client radius use the protocol Radius. But in my case there is no PEAP, EAP/TLS ... Someone can confirm me please if the communication is safe ? because I afraid to see in the file users my password in clear-text. Is it possible to use md5, ssha ... and how ? Thanks, Regards, François