I used to work for Sophos, the British anti-virus company. We had three networks in the office: green, purple and red. Green was the corporate network that everyone had access to, mostly used to read email in Lotus Notes. Purple was an ad hoc network used by developers for various testing machines. Red was connected to the Internet. A few privileged people had a PC on their desk connected to the red network, but most developers did not. There were a couple of red-network PCs around the office that we could use of we needed to look something up.

If we actually needed to download a file (say, an open source project, or some tutorial or documentation), we'd download it there and run a command that emailed it to us. The email would arrive in Notes with the attachment stripped off for virus checking. Some time later, we'd get another email saying that the attachment had been scanned and was available in another Notes database.

It wasn't the best learning environment.