Linux sys as a ADSL router?

Linux sys as a ADSL router?

Post by nicc77 » Fri, 08 May 2009 05:48:04



Hi - I am not a networking expert, but I was wondering... since there
seems to be a number of ADSL routers running Linux, how difficult is
it to turn a "normal" Linux system (stock entry level home PC) into an
ADSL router? Do you need any special hardware/software? Is there any
HOWTO's out there?

I have done a couple of "pass through" set-up's with existing ADSL
routers - but what I'm asking is if it's possible to plug the DSL plug
directly into a system that can "become" the ADSL router - if that
makes any more sense :-)

Cheers all

PS: This is a duplicate of a msg I posted on comp.os.linux.setup -
only realized afterwards it might make more sense here :-)

 
 
 

Linux sys as a ADSL router?

Post by Dave {Reply Address In.Sig » Fri, 08 May 2009 06:36:36



> Hi - I am not a networking expert, but I was wondering... since there
> seems to be a number of ADSL routers running Linux, how difficult is
> it to turn a "normal" Linux system (stock entry level home PC) into an
> ADSL router? Do you need any special hardware/software? Is there any
> HOWTO's out there?

> I have done a couple of "pass through" set-up's with existing ADSL
> routers - but what I'm asking is if it's possible to plug the DSL plug
> directly into a system that can "become" the ADSL router - if that
> makes any more sense :-)

> Cheers all

> PS: This is a duplicate of a msg I posted on comp.os.linux.setup -
> only realized afterwards it might make more sense here :-)

Yes you can, you need to get an ADSL modem card to plug in to your PC, or
use one of the Speedtouch USB modems. I did have that setup once, but the
Speedtouch has been resident on the shelf for some time because I didn't
consider it as reliable as a standalone box. The Linux box is still there
though, it's load-balancing between two internet feeds.

--
Dave

So many gadgets, so little time.

 
 
 

Linux sys as a ADSL router?

Post by Wolfgang Draxinge » Fri, 08 May 2009 09:24:42



Quote:> Yes you can, you need to get an ADSL modem card to plug in to your PC, or
> use one of the Speedtouch USB modems. I did have that setup once, but the
> Speedtouch has been resident on the shelf for some time because I didn't
> consider it as reliable as a standalone box. The Linux box is still there
> though, it's load-balancing between two internet feeds.

Most DSL modems come in the form of ethernet bridges. Technically they're
some sort of media converter. In theory one could connect to the internet
with these directly without the need of dialup software.

But usually PPoEP is used. In short: Ethernet is used to connect the modem
to a computer, but instead of a networking protocoll like IP the ethernet
frame transport PPP.

The DSL modems that connect via USB actually implement USB ethernet
adaptors. So in those devices you connect your computer to a external
ethernet NIC by USB, and that NIC is then bridged via DSL.

Wolfgang

 
 
 

Linux sys as a ADSL router?

Post by Wolfgang Draxinge » Fri, 08 May 2009 09:40:22



> Do you need any special hardware/software? Is there any
> HOWTO's out there?

Special hardware: No.

Special software? Depends on your definition of special.

If special like 'not installed in most distributions by default' then yes.

If special like 'some sort of * program I've to build myself' then NO.

You need pppd with ppoep extension/plugin (any recent version of pppd should
do fine). Also you need a newer Linux kernel for PPoEP support, but only
the very outdated kernel versions lack this.

Quote:> if it's possible to plug the DSL plug directly into a system that
> can "become" the ADSL router

Yes.

Now read this HOWTO:
http://www.veryComputer.com/

This is written for Gentoo Linux, but things are quite similiar for other
distributions. And since Linux is all about freedom of choice, most of the
steps outlined there can be varied in a lot of combinations. For example
this HOWTO mentions dnsmasq. I for myself however use a combination of
dhcpd and djbdns for the same effect and to place my local network into a
subdomain of some the second level domains I own. Instead of ISC ntpd I use
the ntpd of the OpenBSD project, as another variation.

Of course if you just want to refurbish some old box into a router, using a
special purpose Linux distribution developed for that kind of job would be
the obvious chioce. There are fli4l, IPcop and a few others.

http://www.veryComputer.com/
http://www.veryComputer.com/

Wolfgang

 
 
 

Linux sys as a ADSL router?

Post by Wolfgang Draxinge » Fri, 08 May 2009 09:41:22


That HOWTO might come in handy too:

http://www.akadia.com/services/pppoe_iptables.html

 
 
 

Linux sys as a ADSL router?

Post by Andrew Gideo » Sat, 09 May 2009 03:06:37



> And since Linux is all about freedom of choice, most of the steps
> outlined there can be varied in a lot of combinations. For example this
> HOWTO mentions dnsmasq. I for myself however use a combination of dhcpd
> and djbdns for the same effect and to place my local network into a
> subdomain of some the second level domains I own.

I've all this working (though with bind instead of djbdns).  But one
thing I've never found how to do is having DHCP use a predefined hostname
only if the DHCP client doesn't provide one.  That is, I can have DHCP
override whatever the client provides (which can include nothing) as a
hostname by using the ddns-hostname.  Or I can not use that directive, in
which case the DHCP client's provided hostname is used.

But when the DHCP client provides no hostname, and no ddns-hostname
directive is in use, then DHCP sends nothing to the DNS server.

Is there a way to have a hostname that is used by DHCP IFF the client
offers none?  And can this be done w/o any host block (ie. for the range
of IPs used by "allow unknown clients", where the MAC address won't be
known ahead of time)?

Thanks...

        Andrew

 
 
 

Linux sys as a ADSL router?

Post by Wolfgang Draxinge » Wed, 13 May 2009 02:49:52



> Is there a way to have a hostname that is used by DHCP IFF the client
> offers none?  And can this be done w/o any host block (ie. for the range
> of IPs used by "allow unknown clients", where the MAC address won't be
> known ahead of time)?

I can only speak for djbdns, as the last version of Bind I used was Bind 5
IIRC (sometime 1999), then I had a long phase without a own network to
administrate.

djbdns doesn't support ddns, though you could write a helper program, to do
it. No, the solution I used may sound crude, but it's simple and works
reliably:

I just created a generic tinydns-data file, that contains a A record for
each DHCP issued address. And the hostnames are just aliases to those. ISC
dhcpd allows to specify host specific IP addresses also from DNS, i.e.
within a dhcpd.conf file in the host section you can use a FQDN instead of
a numeric IP address. Just make sure, that on the machine running the dhcpd
the zones authorative DNS server is configured in /etc/resolv.conf

Wolfgang

 
 
 

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