Security :: IPTABLES - Restrict Internet Access Based On Time Of Day And MAC Address

I am trying to configure my Linux router to restrict Internet access for one computer on my LAN. It needs to be restrictive based on the time of day and the days of the week. I am using the MAC address of the computer to single out the one computer that needs to be blocked. However, this is my first attempt at making any rules with iptables, and I am not sure if I am doing this right. If some one can take a look at this I would greatly appreciate it. This is what I have done so far.

Here is my thinking. Create a new target. Check the MAC address, if it is NOT the offending computer return to the default chain. If it is the offending computer check that we are between the allowed hours and dates and ACCEPT. If we are not within the time/date range then drop the packet.

Code:

Here I am trying to route all packets regardless of the computer on the LAN into the blocked_access chain for checking.

Code:

Is it a good idea to route all traffic through the blocked_access chain? I do run other servers that are accessible from the Internet, so I am not sure how this setup will affect that. I also use shorewall on the router to setup iptables for me. How would I integrate this with shorewall?

I am using squid to block access when he is using the web browser. However, he is still able to play games(World of Warcraft) and the like.

I am using Debian sid, iptable(1.4.6), shorewall(4.4.6), kernel 2.6.32-trunk-686.