I am trying to redesign the way that my home network is designed. I have two routers, a linksys WRT54G and a linksys BEFSR41. The WRT54G is the top-most router. I have 3 computers that I operate with that I want plugged into to this router. Connected below that router is the BEFSR41. I want this router to connect all of the other computers in the house (ie, my roommates). I would like two subnets in a Class C network using a subnet mask of 255.255.255.192. My question is this. The entire goal of this setup is to ensure that everything of mine which is connected to the WRT54G at the top can connect to anything below it (including computers connected to the BEFSR41). However, I do not want anyone connected to the BEFSR41 to be able to connect to anything on the WRT54G (not even the configuration page of the WRT54G) How can I attain this? Thank you in advance.

You have to change the routers around so that the BEFSR41 becomes the main router and the WRT54G becomes the one below it. Then WRT54G can become a member of the same network with the other computers (your roomate) on the WAN side of the WRT54G, while keeping your own network you personal network on the LAN side of the WRT54G. D

You're creating yourself a headache. Why not just turn off DHCP on the second router and use DHCP on the first to give IP's to all clients. Keep them in the same range and just don't allow clients from your roommates side to connect to shares on your PC's. With my setup, you just need a crossover cable and go LAN port to LAN port to connect the switches. The second one won't require and IP and you won't have to mess with routing tables and firewall rules. Just use it as a switch. This is a LOT simpler to setup than what you're trying and I'd even have to play around a bit to make your proposed setup work properly and I'm a network technician by trade. It's a lot simpler in this case to allow or restrict access to shares on the PC's than to try and do what you want. If you don't create accounts on your PC's for your roomates and remove all users/groups from any shares EXCEPT your account and your administrator account, then they (your roommates) will never be able to connect to shares on your PC's.

You do not protect anything with subnetting. In fact all IP's are subnetted. An IP without a subnet is nothing. A classed is meaningless in this case. You can't even trust security based on mac address on wireless. If you don't want anyone to connect then you need wires not wireless. Any 12 year old kid can get any number or ways to get into your system. There are some more secure enterprise sytems that are a bit harder to crack. Use wep and change keys often is about the best defense.