Does anyone do any serious disconnected computing? I daresay not. We install and update our Linuxes over the Internet, and install new software, and look up information online. Networking is essential to a Linux system, and has always been integral even as our favorite glossy proprietary operating systems couldn’t network their ways out of paper bags. I like to think of IPC– inter-process communication– as a form of internal networking between processes, though wiser network gurus may disagree.

Networking in Linux is easier than it used to be in the olden days. Why, I haven’t customized a kernel in dog’s years, which was something we had to do a fair bit back in the days of walking uphill both ways in the snow. But it’s not quite pure magic yet and we still need to know a few things. Let’s start with routing between subnets. Dividing even a small network into subnets is a useful management tool for security, and for allocating resources such as file and printer shares and Internet access. You can isolate your subnets from each other, or allow them to talk to each other.

Full article here:
Linux Routing Subnets Tips and Tricks (Linux.com)