[Samba] How I get that a host (domain NT) only gives access to a certain user

[Ricardo Chamorro]

How I get that a host (domain NT) only gives access to a certain user. That, for example,  john only has access
to the client IP 192.168.0.11 or, said otherwise, that the host 192.168.0.11 only give access to the user john.
How could I implement it?
I have looked for in Using Samba and Google, but I have not found anything specific...
It is a domain NT run on Debian Woody knl 2.4.25 with Samba 2.2.8 (setting as domain master and users security)
and the clients are W95 and 98 with fixed IP.
Regards
Richard