我的系统上安装了 Ubuntu 12.04，用作我办公室的服务器，办公室有 50 名员工。我的系统中有 2 个 LAN 卡：
One for input from a BSNL router (192.168.1.250) to my Ubuntu server (192.168.1.1.)
Another one from the server (192.168.1.1) to a switch which connects all the employees through squid from that switch via LAN cables.
我该如何配置 LAN 卡和 squid？