how do i block a particular client internet access

From:	"jan gestre" <m0n0wall dot list at gmail dot com>
To:	"MonoWall-General List" <m0n0wall at lists dot m0n0 dot ch>
Subject:	how do i block a particular client internet access
Date:	Sun, 9 Apr 2006 05:42:20 +0800

guys,

how do i block a particular client pc via its mac address? i'm not  using
captive portal and clients obtain their ip addresses via the monowall's dhcp
server.

TIA