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My home network setup is just a typical one. A "dump" box from Vodafone containing everything (ADSL modem/router + 4-port Ethernet switch + Wireless access point).

Since I am kind of a techie, I don't like that kind of setup and I need to be able to configure everything by hand (NAT using iptable rules, etc.). So, I decided to setup an external Linux box as the router (Internet gateway) for the rest of the LAN according to this guide: http://www.gentoo.org/doc/en/home-router-howto.xml

So, my question is: Is it possible to just leverage the Access point and the ADSL modem functionality in the dump box while using the external Linux router so that I don't need to buy both (modem + AP) separately?

Googling on the issue of the AP I know it can be done by disabling DHCP in the dump box and using a DHCP server in the Linux gateway with an IP address range that doesn't include the IP address of the dump box. The issue with me is that I want to do BOTH things (The AP and modem).

The thing that confuses me the most is how to bypass the PPPoE configuration in the dump box so that the one in the Linux box can take effect without conflict, specially that the configuration interface for the dump box doesn't contain any controls for disabling PPPoE. It just contains fields for the parameters (like username, and password, etc.). Or am I a bit pessimistic and things would just work once I configure the hosts on the LAN to use the new Linux gateway?

Any help would be really appreciated. And thanks for your time.

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2 Answers 2

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You should be able to just chain them. I have an Apple Time Capsule behind my provider's ADSL gateway (modem/router/AP). The Time Capsule warned me about double-NATting during setup but allowed it, so I effectively have two NAT firewalls. It's been in use for several years with no ill effects I can see.

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Yeah, I think it should work fine with double NATing. However, I have to first buy an external AP for the internal LAN behind the Linux box, and use the Vodafone box just as a modem, because the AP and the modem must be on separate networks with the Linux box acting as an internal router in between. I would rather, though, to have the PPoE client in the Linux box, and use the Vodafone modem just in bridged mode like mgorven said in his answer, but as I said in the comment, the shitty box from Vodafone is very low on features and doesn't have an option for bridged mode. –  Marwan Feb 26 '13 at 8:27

The way that ADSL is usually handled is to put the modem into bridged mode, and run a PPPoE client on the Linux box. The modem then simply provides transport between the Linux box and the access concentrator, and the Linux box has the credentials for creating the connection and is responsible for routing traffic through the ADSL connection.

In terms of DHCP you want to setup a DHCP server on the Linux box, and disable the DHCP servers on both the modem and the API. You probably want to give the modem and AP static IPs on your subnet so that you can access them for management.

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Thank you for the reply. My current router/modem doesn't seem to have any option for enabling bridged mode. just 4 options for PPPoE, PPPoA, IPoA, and EoA. So, is there anything I can do in this case? –  Marwan Aug 27 '12 at 7:35

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