Security Flaw? or My mistake?

[kenweill]

I have a linux box Ubuntu 7.04 setup to share an internet connection with my other pc. The other pc is installed with Windows XP. Its connected to a Local Area Network(wired). My Ubuntu box is connected to the LAN, and at the same time, connected to the internet via Wireless Broadband.

In my LAN, i set a workgroup named "WORKGROUP". With similar Computer Names(Workstation11, Workstation12, etc...).

Now here's the weird part.
When I browse to LAN from my Ubuntu box, I see all the 6 computers(my LAN computer) under WORKGROUP. Plus, theres another one, not part of my LAN, the 7th.

When I browse to the 7th computer, it contains files, pictures, videos, etc.... The 7th computer is named with the family name of my neighbor.

How come my neighbors "shared documents" appear in my LAN? We're not connected. The only common connection we have is that we both have the same ISP, connected through Wireless Broadband.

If I was able to view their "shared docs", then theres also a possibility that my neighbor can also view mine. Or other users in the neighborhood with the same ISP...

Is this my fault? ISP's fault? Or my neighbor's fault?

I need comments about this....

[Sayers]

That's their fault. Ubuntu doesn't share doccuments unless you tell it to.

[kenweill]

That's their fault. Ubuntu doesn't share doccuments unless you tell it to.

What about my windows computers. It has shared documents too. Is there a way to only allow outgoing connection from my LAN to the internet, and denying all incoming connection from the internet to my my LAN. Or something like that.