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Re: Spesial PPP configuration.
Hi.
Some people have asked for more information concerning connecting machines
through one machine, without having IP addresses. Let me clarify.
Being on the Internet, means that you have an IP (Internet Protocol)
address of your own allocated to you. It also means traffic from anywhere
in the world to that address is somehow routed to you. A computer
without an IP address is NOT on the Internet.
What Sefi originally asked is this: I have a computer on the Internet.
That same computer is on a LAN with other computers NOT on the Internet
(no IPS). How can I make it that those computers will be able to access
the Internet anyway?
If Netscape is enough, there's an easy solution. The machine connected
to the net can run a proxy, and all the Netscapes on the LAN can use it.
This means that when a Netscape user selects www.linux.org.il as
a destination, Netscape uses the local LAN (also running TCP/IP) to
contact the machine with the proxy. The proxy finds www.linux.org.il's
IP address and understands that to reach it it must go to the Internet
(via the PPP link, for example). It thus sends out a request on the
Internet to www.linux.org.il and gets the page. It then sends that
page on the LAN to the Netscape user.
If you want more, an option exists called IP masquerading. This means
you have the router machine (=the one connected to the Internet, even
with PPP) is running special masquerading software. This software receives
requests from a computer on the LAN, and modifies the return addresses
so that the packets will come back to the router (they can't come
back to the original machine, since it ain't on the net). When the
router gets the repsonse from host it sent the request to, it sends
the info backto the client on the LAN. This is more complicated. For
those of you who've asked for help on how to do this, I have no idea
where to find howtos, although you should look at the NET-2 howto,
the firewalling howto, search the various Linux sites, and take a look
at Linux Journal issue 27 (July 1996, titled "The Shell Game").
Shay
--
Shay Rojansky, roji@cs.huji.ac.il Finger for PGP public key
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