non-firewall security

block services through just two files:
/etc/hosts.allow
/etc/hosts.deny
each has simple format: daemon:host1,host2,domain1,domain2
system reads allow, then deny, until a match is found, then it quits
changes take effect immediately
want to allow everything? ALL : ALL
want to block the 192.168.15.0 network? 192.168.15.0/255.255.255.0