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How to
configure your Alcatel SpeedTouch ADSL
modem to act as a transparent bridge?
This
document describes how you can configure
an Alcatel SpeedTouch Pro ADSL modem not
to use NAT anymore, and not to perform
the dialing to the ISP.
Note
that you'll need a software login method
to achieve a connection to ADSL.
Alternatively, there are many relatively
cheap and/or better Routers on the
market which perform these "port
forwarding" requirements in a much
easier and reliable manner.
This
process is often called BRIDGING. The
Alcatel modem will not receive the true
IP address from the ISP, instead it will
be sent to your machine or Internet
Gateway box (or router). BRIDGING in the
case of the Pro, is just a fancy name
for turning it into an ordinary ADSL
modem and switching off the Security and
Internet Sharing features. This often
becomes necessary when trying to allow
services like MSN Messenger, VPNs or
even running certain Servers.
The
difference between BRIDGING and DHCP
SPOOFING (described here Configure
Alcatel SpeedTouch ADSL for DHCP
Spoofing) is that with bridging the
end-machine/router does the dialing, and
so it gets the real IP address from the
ISP. With spoofing the modem dials for
you, receives the IP address from the
ISP, and then gives it to the
end-machine/router.
As
stated, this process will therefore
eliminating NAT on the Alcatel modem. It
is also useful for setups where
combination of an Ethernet gateway
routers which have PPTP dialer support
are in placed. Doing so will enable you
to configure an internal router or a
server that has routing software
installed and have it receive an IP
address from your ISP - instead of
having the modem obtain the address for
you.
This
method will work if one of the following
assumptions is true:
-
Your modem is connected to the
Internet and another computer is
connected to your modem.
-
Your modem is connected to the
Internet and you have a router that
is connected to the modem. This
router must have NAT capabilities
and PPPoE dialing capabilities. The
router will then be connected to a
hub/switch, and to it other
computers will connect.
-
Your modem is connected to the
Internet and you have a server
computer that is connected to the
modem. This server must have Routing
and NAT capabilities and will be
configured to dial to the Internet.
The server will then be configured
with another NIC, and to it you
connect another computer.
-
Your modem is connected to the
Internet and you have a server
computer that is connected to the
modem. This server must have Routing
and NAT capabilities and will be
configured to dial to the Internet.
The server will then be configured
with another NIC, to which you will
then connect a hub/switch, and to it
other computers will connect.
Make a
note of the fact that the modem will
stop acting as a router with NAT/PAT
which means that you'll have to connect
it to a router or server that has NAT
capabilities. Without such configuration
you won't be able to connect to the
Internet. |
