Replace ADSL router with Debian Linux

Is there a way to replace ADSL router with Debian Linux? Some software that would make a Debian server behave as an ADSL router?
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In many cases you can convert the ADSL router into an ADSL bridge such that the public IP will be on the router/debian system.

the ADSL adapter in bridge mode will handle the encapsulation while the system behind will need to send the PPPoE data to establish a connection and get the IP/s.
Which ADSL router do you have?
They may use different terms Bridge, Pass-through, etc.

Note to record how to get back into the router once it is no longer in routed mode when available just in case you want back in.

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itniflAuthor Commented:
I think it is a Inteno DSL Router X5668.
I am getting another DSL line soon, then I will have two. The central where I a does not offer veru high speeds because of old equipment. I then need two lines to get the speed I need. I will then have to have two DSL routers and a Linux router to load balance the two. I would like to get rid of as much equipment as possible and just connect the Linux router directly.

Does your debian system have multiple Network Interfaces at least three?
1) external Connection 1
1) for external connection 2
1) for the LAN.

Check with the ADSL providers about configuring the Adapters in bridge mod.

Look on page 26 for your Interno DSL router X5668 for details on changing it from routed mode to bridge mode.  Note that this change will likely disable the wireless functionality of the router.
Make sure you do not switch until your debian firewall/router is setup.
Or use one of the DSL as a test
i.e. slow DSLin bridge mode + debian firewall/router with one LAN system for testing. Once you are satisfied that it works, you can consider converting the other and dropping it/terminating the second ADSL connection on the debian router.

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I agree with others about turning your adsl-router into a bridge. I've got a company that produces open source routers as a building block in some services that we sell. But I will not say anything more about that but I can give you some small advice about pc-routers. I've set up debian routers for Spotify at one time, because they were very keen on having just debian in their network for servers and other stuff. But the problem is, IMHO, that debian has a bit old kernels. That said, debian is a good operating system but I would suggest you roll your own kernel, or at least grab a newer kernel. I usually build a router out of gentoo due to that I like to have the latest pacthes for networking. If you want a bit more routing capabilities you should use bird, quagga or similar. I use quagga. And take a good look at tc (traffic control), keepalive (vrrp part) and iptables. I gather that you already know a bit about iptables but it's good to learn more about it. Especially about marking packets for some kind of policy based routing and other stuff. Keepalive is good in routing if you need resilience (two routers or more) for hosts that only have default gateway as routing. Tc is very good to have if you need some sort of control of how the flows should behave. Another good thing to have is some IDS like snort or even argus.
If you are really looking for the best control and have the money to do it, replace the supplied adsl modem with a dual port adsl pci card that goes right in the server. Traverse makes one that's well supported in recent kernels. The cards are fairly pricey though.
itniflAuthor Commented:
Thanks for good replies. I will be waiting to close this thread a bit, so that I can have time to evaluate this further. Please keep posting if something comes to mind.
Why are you trying to do this? Reducing boxes isn't always best. Are you trying to replace the router function or the modem function or both? Changing out the router function is fairly straight forward so long as you have 2 or more network cards in the server ( Getting modem function into the server requires more expensive hardware and support like darrickhartman mentioned. It's a lot less work to ADD more hardware, starting with something very basic like a TP-LINK TL-R470T+ Load Balance Broadband Router , or a more complex answer from DrayTek.

itniflAuthor Commented:
With two DSL lines, the DSL provider ships me two DSL modems. I would like to use only one. Buying a modem that load balances for me is great, but not having to buy anything and just use an old PC as a server to load balance would be better. However I guess that an old PC would use more electricity over time then a a dual DSL port DSL modem/router.

As I already mentioned, I would be looking for replacing two DSL modems/routers with a Linux box. This implies I want to replace both router and modem functionality.
To get ADSL functionality into a linux box, you would need to buy the card that does the ADSL functionality as darrickhartman referenced.
You can always use the ADSL modems that the ISP provides, change them to Bridged mode where the only functionality they have is to handle the Communication/connection to the DSLAM of the providers passing the IPs to your Linux box where each will be connected to its own network interface and pppoe configured on each to send the authentication information if needed and then use the HOW-To that setups up a linux based router. with the Third Network Interface dedicated to the LAN.
You can always adde additional Network cards with multiple ports i. quad port Network interface are available as well.
There are a some dual WAN routers, but I've yet to come across any with a single built-in modem, let alone two. It's possible someone has come across such devices, and if so, please post models and/or links. In the mean time, if maximum speed is your major criteria, you won't be able to get past the most expensive solution mentioned earlier involving buying expensive modem cards. I'd still recommend going with dedicated hardware for simpler and more reliable solution.

itniflAuthor Commented:
Since this is more of a discussion with many possible right and wrings, I a awarding points to all suggestions. Thank you, all suggestions will be evaluated as possible solutions.
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