allowing ssh client from a certain subnet only

From: pui ming Wong (s11976_at_net2.hkbu.edu.hk)
Date: 06/23/03 

Date: 23 Jun 2003 05:57:39 GMT

I run sshd as a daemon (not from inetd.conf)
As a newbie, what are the stanzas in the sshd config file
that could deny all client access EXCEPT from
a certain network
say, xxx.yyy (which is a Class B network)