And, yes, it is (sometimes). In XP, right click a folder, select “Sharing and security” (no: Deling og sikkerhet), then check the box “Share this folder on the network” (no: Del denne mappen på nettverket”, select a sharename. Everything seems fine. But when other try to connect, typing \\mycomputername\ in the file explorer, it times out. wtf?
It should have been obvious to me, but I don’t consider myself a windows user. I run Win XP on my Mac OS X through VMware, which works fantastically. Solution; you probably have a firewall blocking port 445. Probably not the windows firewall as I guess it opens this port automatically. Check your anti-virus software firewall!
I use McAfee, there you need to select Advanced Menu (bottom left)-> Configure (bottom left) -> Internet & Network (left sidebar). Is firewall protection on? If yes, click button Advanced -> System Services. Open service port “Microsoft Directory Server(MSFT DS) Port 445. Click Apply and test from another computer that you have access.
There might be security issues related to opening this port, google hits are confusing to me. Anybody know more? As I only want read & write access to a folder within the local network I added a block on port 445 to my router, a Linksys WRT350N, to block access from the internet. In the admin gui I added a security policy (tab Access Restrictions), manually adding the port 445 to Blocked Applications.
By the way, I just discovered this, for F-secure client users.
I asked a lot of people and I spent a lot of time googling around. Actually I first opened the ports 137-139 for NetBIOS, which is a real security issue (It did work too). But then I found this article about windows file sharing and it was really educational. Seriously though, I should never have needed to spend this much time on such a simple matter. I hope you won’t have to, after reading this!