This service was mostly used in the old days for remote administration but now because of security issues this service has been replaced by the slogin and the ssh.
Default port: 513
PORT STATE SERVICE513/tcp open login
apt-get install rsh-client
This command will try to login to the remote host by using the login name root (for this service you don't need to know any password):
rlogin <IP> -l <username>
find / -name .rhosts