"BRG" <(E-Mail Removed)> wrote in
news:Xns9436790F3D4B3BRGxxx@62.253.162.115...
> > My problem now is - how do I see the Internet via my laptop. The
> > AOL broadband connection I have goes in to my desktop.
> Just for the record, a router-based solution is *not* an option for
> AOL ADSL broadband in the UK.
Could you be more specific, why?
What are the technical details that prevent the use of a NAT-router or
MS-Windows ICS (Internet Connection Sharing)?
A frequent question in this group is "how to share a broadband connection of
brand name X"? The standard answer seems to be to use a proxy server.
(I cannot realy see why people call this sharing. What you are really doing
is connecting *your* home network to the Internet. You are not *sharing*
your connection with anyone.)
I set up my first proxy network in 1996. If I remember correctly the name of
the program was "NetProxy". Had to send a check of £20 to the manufacturer
in the UK to get the licence activated.
Since then I thought proxy technology was dead. Windows 98 Second Edition
came with ICS (= NAPT) built in, so there did not seem to be any reason for
using proxies, even in an all Windows environment.
****
The standard way of connecting a private network to the Internet through one
connection, or more precisely sharing one IP address for a whole network is
to use Network Address Port Translation NAPT. (Often refered to as PAT or
simply as NAT.)
A private network with a private IP address space (typically 192.168.0.0/26)
is connected through a router doing address translation. The same device can
also do statefull inspection of packets and act as a firewall.
This address translation can be done by Linux, by Windows using the ICS
feature or by a dedicated NAT-router/firewall device (also known as a
"broadband router"). The number of hosts behind NAPT is only limited by the
size of the translation table in the router device (typically 256 - 10000)
and ultimately by the number of different port numbers, 64k.
In Finland NAT-routers are being used to connect whole appartement buildings
to one (or two) ADSL connections. The bill for the ISP-service is shared
between the connected users or picked up by the housing co-operative.
****
There are a few ways the ISP can try to restrict the number of hosts
directly or indirectly connected to service. Most can be easily overcome.
1) Limiting the number of IP addresses. Some ISPs offer up to five IP
addresses for one subscription. If only one is available, then NAPT as
described above is the solution.
2) PPPoE: The ISP might require connection over Point to Point Protocol over
Ethernet. This should not cause problems. Most broadband routers have built
in support for PPPoE.
(If you use ICS with PPPoE you may not even need a second NIC on your
Windows computer. The PPPoE appears as a virtual interface. You can "share"
this virtual interface on the physical interface.)
3) MAC address control: The ISP may require that physical MAC address of the
NIC be registered thus preventing other devices from being connected to the
service. Most broadband routers offer a "MAC cloning" feature where the MAC
address of the NIC is copied to the WAN interface of the router.
4) VPN (Virtual Private Network): The ISP may provide the customer with a
VPN client program and require that the connection is formed using this
client. The client program may block all other TCP/IP interfaces thus
disabling any ICS.
Ïn practice all VPN clients use standard VPN protocols (PPTP, IPsec) so any
standard VPN client supporting the protocol, including Windows built in
clients, will do.
--
Petri Krohn
petri. krohn <a@t> iki. FI(nland)
__________________________________________________ ___________
Fiber-optic Community Networking:
http://www.HelsinkiOpen.net
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