I think you need to specify a list or range of IP addresses.
Code:
/home/files 192.168.3.0/24(rw)
or
Code:
/home/files 192.168.3.0/255.255.255.0(rw)
Either of the above should work, but I can never remember exactly how to specify the mask in CIDR notation. The above examples will allow access from any host between 192.168.3.1 and 192.168.3.254. So depending on your needs, you might want to narrow it down some.