Can workgroups 'overlap'?

  RockBrighton 11:06 01 Apr 2006


I'm a newbie with very little understanding of home networking so I hope I'm posting to the right place ...

Is it possible to use one computer to connect to the Internet (using it for that purpose and printer sharing only) and for, say, 3 independent LANs to share its Internet Connection but not be members of the same workgroups and therefore invisible to each other?

I'd find it easier to draw a diagram to explain my question (though don't know how to here!) but using letters the workgroups would look like this:

LAN/Workgroup 1: Computers A1, A2 and Z(>Internet)

LAN/Workgroup 2: Computers B1, B2 and Z(>Internet)

LAN/Workgroup 3: Computers C1, C2 and Z(>Internet)

where computer Z just provides/shares the Internet connection and printer and is common to (and can be seen by) all workgroups, but networks 1, 2 and 3 can't see or share files with each other.

The operating system is xp pro sp2.

Apologies if this is the dumbest question in the history of networking but I find the subject very confusing!


  Smiler 11:52 01 Apr 2006

This should be posted in the networking forum methinks.

  RockBrighton 11:59 01 Apr 2006

OK - sorry. I'll copy and paste it there and just hope I understand any replies! How do I delete this post; do I just check 'Resolved'?

  Forum Editor 12:04 01 Apr 2006

why would you want to do this in a home environment?

For a start, you would be far better off using a router for internet access - that way you wouldn't need to have any one machine running in order for others to access the internet.

As far as separation goes, if you do this you'll be involved in separate IP address ranges, and it can get fairly complicated. Unless you have a specific reason to do otherwise I recommend that you run a single LAN. You could always use firewalls to block access from specific IP addresses, but I've never seen a home network where it was necessary.

  Forum Editor 12:05 01 Apr 2006


  RockBrighton 15:18 01 Apr 2006

Thanks for the response.

The reason we have a computer doing the job of a router is 'historic': my son set the system up originally using an old PC as a proxy server (don't know what that is or why!) but it would tend to go awol while he was at work and he got fed up coming home from working with computers to spending his spare time working with computers! So he changed it to the existing system - one (peer-to-peer?) network using the old proxy server as a router.

I asked him if it could be changed to what I've suggested above, thinking it might be easy, as my neighbour and I share the internet connection, costs and LAN in the interests of economy but, though we're good friends, we don't particularly want to be in the position where we can share each other's files and folders - yet we want to be able to share our own respective files and folders between our own, separate PCs and laptops. My son says he didn't think it was possible but, although he knows 50 times as much as me (not difficult!) it's not really his area of expertise.

The domestic/sharing situation is actually a bit more complex than that (hence the original requirement) so, if there's a way of achieving the desired outcome without breaking the bank or signing up for Open University - especially using simple words (for a simple fella!), I'd love to hear it.

Thanks again.


  ade.h 15:37 01 Apr 2006

Are ALL your clients using XP Pro?

(I'm thinking here about Simple File Sharing and the disabling of).

  RockBrighton 15:47 01 Apr 2006

I think my neighbour might be using the 64bit version of Windows ...

Wouldn't disabling file sharing mean that I couldn't see my own laptop files on my own desktop either?

  ade.h 17:48 01 Apr 2006

Disabling file sharing???

I was talking about Simple File Sharing.

  ade.h 17:50 01 Apr 2006
  LastChip 19:05 01 Apr 2006

This is certainly not "dumbest question in the history of networking". In fact, it's quite an interesting one.

The quick answer is, yes it can be done, but not without a fairly good knowledge of network topography and protocols. It can be remarkably easy to "break" XP Pro's networking, so if I were you, I'd stay clear.

ade.h's suggestion of turning off Simple File Sharing is probably your best bet and remember, you can create directories or files that are encrypted as well if you wish, for extra protection. But for goodness sake, don't loose the keys!

The other alternative is to place a software firewall on each machine, and configure it to only accept requests from your own network and the network "gateway" machine. This normally involves specifying which IP addresses the firewall will accept. So if we use your example, computer A1, would only accept requests from A2 and Z. All others would be rejected. On some firewalls, you can also tie in the MAC address for extra protection. This is a unique address assigned to your network card.

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