Rsh works one direction

[r.ford at cox.net]

Hi,
I need some idea where to start looking next on this problem.
I've tracked it down to an authentication problem.  But rsh did not work before I started using yp-nis for authentication.
(oh, and please don't bother lecturing me on the security of rsh. thanks)
I've got rsh working one direction...www -> frogger
frogger won't rsh to www but it will rlogin after i provide a password.  rlogin goes to frogger without asking me for a password.

       frogger->www   www->frogger
rsh             yes   no, with list of trials and errs
rlogin          yes   yes, with list of trials and errs, 
                       and user-prompt for password.

Here is the rlogin from www->frogger:
www ~]$ rlogin frogger
connect to address 192.168.0.90: Connection refused
Trying krb4 rlogin...
connect to address 192.168.0.90: Connection refused
trying normal rlogin (/usr/bin/rlogin)
Password: 
Last login: Sat Dec 31 09:56:44 from www
frogger ~]$ 

Here is the rsh from www->frogger:
www ~]$ rsh frogger ls
connect to address 192.168.0.90: Connection refused
Trying krb4 rsh...
connect to address 192.168.0.90: Connection refused
trying normal rsh (/usr/bin/rsh)
Permission denied.
www ~]$


Thanks for any ideas.
Rod