I think I am missing the big concepts here and so too perhaps others are in the same position. The goal of this project is obtain content filtering via the ADDITION of an Ubuntu server with Squid proxy, ultimately to be transparent/intercepting, and then to add Dansguardian. My desire is to do this as an addition to my existing environment leaving much of the present hardware router functions in place. I have selected Ubuntu server because it is the only linux I have any real exposure to (and this is quite limited). I have managed to do the Ubuntu server install (many times actually) followed by apt-get update and upgrade and then install of openssh-server followed by install of squid. Initially I had only the onboard nic in this box but I have since added a second nic. I can manage edit of interfaces to change from DHCP to static for both of the nic's. With the single nic setup I was able to do some basic squid configuration and then successfully pointed my workstation browsers to the proxy. I never managed to get to the point of transparency though as I became confused with the 2 nic setup and with the generally topography. In the present environment I have FIOS internet so I am stuck with an actiontec router. The actiontec is also handling some wireless connections. The actiontec is also required to get guide information on the fios set top box In a second location I have DSL and there is a Linksys router handling the connection. In a third location I have DSL with a sonicwall TZ180 with advanced bios installed. Regardless of location, the hardware routers are doing the DHCP and there is some port forwarding in place in these routers. Where I am confused is in understanding the number of nics required, the number of subnets required and how the role of the hardware routers will change with any of the possible new configurations For the sake of this discussion, the hardware routers are 192.168.1.1 and the workstations get IP addresses from the hardware routers dhcp starting at 192.168.1.100 (some of these are wireless). I have some workstations with static IP's set as well (theoretically ranging from 192.168.1.2 - 192.168.1.99) The big questions follow: 1. Does this project require that the squid box have 2 nic's or is it merely suggested. 2. In the even that 2 nics are suggested or required, should they be on the same subnet or on different subnets 3. If I elect two nics with 2 subnets, it seems the workstation machines will no longer get dhcp leases from the hardware routers (or will they) and also the port forwarding that the hardware routers presently handle will be lost. Again, the main goal is to get content filtering in place, for this to be transparent/intercepting, while maintaining, to the extent possible, the functions of the hardware routers presently in use.