does anyone know how to stop rlogin to my sunsolaris

so I have 2 machines...I can not telnet one becouse that is not allowed but I can telnet the other and do rlogin to first one..I want to stop that..

so..

telnet A from C machine - works
telnet B from C machine - does not work
but telent A from C and then rlogin B - works
that should be stopped...

any help?? please...