Anna has received a new laptop from the university on Thursday (a Dell Latiture D520) and yesterday I was trying to set up a home network to share files (between our desktop PC and the laptop) and a printer (which we bought and connected to the laptop).

After some unsuccessful tries, I came to the understanding that the firewall is blocking sharing. The firewall I'm using is Sygate Personal Firewall (SPF), and so far I've had no problems with it. However, it automatically blocks unsolicited accesses from outside to the ntoskrnl.exe process which apparently manages the sharing. Asking it to allow all traffic for ntoskrnl.exe just didn't help - it still blocks it (probably because the process does not initiate the traffic).

I almost made peace with the restriction to turn off the firewall when I want to print something from the desktop computer or to share files. After all, my home network connects to the internet via a router, so it's relatively safe anyway. Today, however, I managed to solve the problem. SPF allows to define "advanced rules" which override all the regular traffic rules, in Tools -> Advanced Rules. I added a rule that allows all incoming and outgoing traffic to and from -, which is the IP range of my home network (well, in fact I only have two computers in it, with endings 1 and 2, and a router with ending 138). And what do you know - it works very well. Now I'm able to share files and the printer even through the firewall.