Well seems I've created a big debate. Thanks for all the input guys most useful.

I conclude that my best bet is to find a ADSL2/2+ router that I can replace the ISP's router with that gives me the Guest access I want.

Any recomendations?

tracert reveals going through a 192.168.0.x address and if you know gateway IP then that would be first target and with a 255.255.255.0 subnet only 255 IP's to query for interesting services.

The FON gets around this by actually using a tunnelled connection, which means the guest users appear as a FON IP address, nothing to do with your broadband IP.

It is also worth considering the legal implications, and how much logging is needed to prove it was not you do carried out various activities

In reply to a post by MrSaffron:

tracert reveals going through a 192.168.0.x address and if you know gateway IP then that would be first target and with a 255.255.255.0 subnet only 255 IP's to query for interesting services.

The Guest network is a separate network, so your solution won't work.

No it is not, not in the scenario as presented in the original post, bashes head against wall. If the scenario is that the the shop network and guest network are BOTH connected to the LAN side of the linksys then you are right.

OP WAS

INTERNET----ROUTER----SHOP NETWORK----LINKSYS----GUEST NETWORK

reasonable solution would be

INTERNET - NON-NAT ROUTER ---- LINKSYS ----GUEST and SHOP on different LAN ranges, with the guest functionality blocking access to the shop network

In reply to a post by MrSaffron:

No it is not, not in the scenario as presented in the original post, bashes head against wall. If the scenario is that the the shop network and guest network are BOTH connected to the LAN side of the linksys then you are right.

OP WAS

INTERNET----ROUTER----SHOP NETWORK----LINKSYS----GUEST NETWORK

reasonable solution would be

INTERNET - NON-NAT ROUTER ---- LINKSYS ----GUEST and SHOP on different LAN ranges, with the guest functionality blocking access to the shop network

Ah, I see why you're confused. You're talking about a standard router, but I'm talking about a Linksys E-series with it's Guest Access solution.

In the scenario explain then how

INTERNET----ROUTER----SHOP NETWORK----LINKSYS----GUEST NETWORK

and the Guest Access solution stops people seeing the Shop network, remembering it is effectively on the WAN side of the linksys.

That's it's Raison d'�tre - that's what it does.

Really it hides content on the WAN side of the router? If it does that then how do people see the internet...think about it for a moment.

The guest mode will only hide a LAN that is connected to the LAN side of the router.

In reply to a post by MrSaffron:

Really it hides content on the WAN side of the router? If it does that then how do people see the internet...think about it for a moment.

The guest mode will only hide a LAN that is connected to the LAN side of the router.

Why not get hold of one and do a review? I don't think you're going to take my word for it...

No, just answer the question.

How does guest mode hide IP addresses on the WAN side of the router?
I fully understand how it stops you from seeing computers on the LAN side, that using the standard wireless or ethernet, but short of creating a tunnel ala FON I don't see how what you suggest you work.

One option would be to configure the routers firewall to block access to the local IP address range that is on the WAN side, BUT you would have to remember to allow the gateway IP address to be visible still.