ADSL ethernet modem (not with a router)

After the very quick help and advice I got a few days ago, I'd like to ask a
few more questions (please !)

I'm the guy that's using a new TP-Link wireless router with a BT Voyager
2100, (mainly to get the better Wifi range, but also because I was stupid
enough to not notice that the TP didn't have an in-built modem ..)

Thanks to the great help from this newsgroup, they're now working fine with
the TP's LAN port 1 connected to the Voyager's LAN port 1, and the Voyager's
Wifi switched off.

My next questions are:

I'd still like to get a secondhand ADSL modem that can plug into the TP's
WAN port so that I can switch off my Voyager and keep it as a first reserve.
Ideally, I would like one with more than one ethernet port, so that I could
then use it also for a 'bare' pc on the outside of the TP's firewall, but I
guess as soon as it has more than one port it becomes a NAT router, and I'm
back with my Voyager situation ?

I've also been looking at the D-link DSL-300T, which has a single ethernet
port and a USB port, with no mention of the word 'router'. I assume I would
be able to plug that into my TP's WAN port, and if so, could I then plug the
USB port into my 'bare' 'firewall-less' PC as well ?

Do any other cheapo secondhand ADSL modem only devices come to mind ?

Thanks again for all the help.

"Paul" <(E-Mail Removed)> wrote:
>
>Do any other cheapo secondhand ADSL modem only devices come to mind ?
>

I got my D-link DSL-300G+ plugged into a linux NAT router. Works a treat, the
ethernet card in the Linux box gets the external address (via DHCP). It's
quite old now; must be available second hand. It won't give me any line
quality stats though. :-( And you have to set it up using the same network
card as you'll be using it with... think it's a security thing to stop someone
pinching the modem and using your account details. Perhaps. Odd.

dom.

Hi Dom,

Thanks for the reply. I think I'll get one of the 300g's off eBay then,
they're pretty cheap on there now, so experimentation won't be too costy,
and it'll do as a backup anyhow.

I read somewhere that they are one of the few ADSL ethernet modems that can
'present the broadband connection directly to a router'.

Any expert reading my drivel can see that I'm blundering about here, but I
think I'm gradually getting some of it together with these helpful replies.
I wanted to be able to have one PC 'on the outside of the hardware
firewall', (physically), so that I could experiment with it as an IIS (with
nothing private on it). But I think the penny is beginning to drop for me
now, I need the router's NAT to allow multiple PCs from the one provider
assigned address, so if I stick another machine in on the 'mains' side of
the router, the packets won't know which way to go ?

(Be gentle with me if I'm talking rubbish here..) I managed to grasp TCP/IP
a few years ago, and I think I need to read up a bit more on
NATs/Routers/ADSL/Firewalls etc., but the average textbook on the subject
makes me fell like Homer Simpson ("every time I learn something new, it
pushes some old stuff out"...) I have noticed that there is actually a
'Firewalls for Dummies' in print (my intelectual level), has anyone seen a
copy and have any views on it ?

thanks again..




"Dominic" <(E-Mail Removed)> wrote in message
news:dtphvv$7ls$1$(E-Mail Removed)...
> "Paul" <(E-Mail Removed)> wrote:
> >
> >Do any other cheapo secondhand ADSL modem only devices come to mind ?
> >
>
> I got my D-link DSL-300G+ plugged into a linux NAT router. Works a treat,
the
> ethernet card in the Linux box gets the external address (via DHCP). It's
> quite old now; must be available second hand. It won't give me any line
> quality stats though. :-( And you have to set it up using the same
network
> card as you'll be using it with... think it's a security thing to stop
someone
> pinching the modem and using your account details. Perhaps. Odd.
>
> dom.
>

On Sat, 25 Feb 2006 09:20:22 -0000, "Paul" <(E-Mail Removed)>
wrote:

[...]
>
>My next questions are:
>
>I'd still like to get a secondhand ADSL modem that can plug into the TP's
>WAN port so that I can switch off my Voyager and keep it as a first reserve.
>Ideally, I would like one with more than one ethernet port, so that I could
>then use it also for a 'bare' pc on the outside of the TP's firewall, but I
>guess as soon as it has more than one port it becomes a NAT router, and I'm
>back with my Voyager situation ?

These DSL modems through ethernet are a bit of a hole - they are
basicly routers but that are set up in such a way that it will turn
off NAT by default and assign via DHCP the IP address of the WAN
interface. You could buy a D-link that does this - I believe Linksys
also do one, or you could buy a cheap Conexant based router (such as
the Safecom SAMR4112, which whilst acts like a router by default, can
be changed to bridging mode very easily.

Either way, you can probably get something from Ebay for very little
money, or new for less than £20 from an Ebay shop or whatever.

Thanks.
Andrew.
--
Andrew Hodgson in Bromyard, Herefordshire, UK.
My Email: use <andrew at hodgsonfamily dot org>.

Andrew Hodgson <(E-Mail Removed)> wrote:
>
>These DSL modems through ethernet are a bit of a hole - they are
>basicly routers but that are set up in such a way that it will turn
>off NAT by default and assign via DHCP the IP address of the WAN
>interface. You could buy a D-link that does this - I believe Linksys
>also do one, or you could buy a cheap Conexant based router (such as
>the Safecom SAMR4112, which whilst acts like a router by default, can
>be changed to bridging mode very easily.
>

Ah, that makes sense... but if it (the DSL-300G+ ethernet modem,
I mean) was a sort of 'straight-through' router, wouldn't it appear
in the traceroute? It does have its own address too - 192.168.0.1 -
with a web and telnet interface on it for setting it up, but traceroutes
show the first hop as the ISPs routers. Perhaps 'bridging mode'
is the important point that I'm missing here!

As you can tell, I really should learn more about IP networking!
Anyone know any good books? Teach Yourself IP in 5 minutes?

dom.

Thanks again Dominic and Andrew,

It's all coming together now (slowly !).

I had a look in the bookshop yesterday, thinking od getting "the idiot's
guide to firewalls", (yes, there is just such a book). It was OK, but maybe
still too specialist, so I settled for the 'Absolute Beginner's Guide to
Home Networking', by Que, ISBN 0-7897-3205-X

As with most of these books, they are 4 times thicker than they need to be,
with all of the blank page space and large type, but I'm working my way
through it, and it is giving me a wider understanding.



"Dominic" <(E-Mail Removed)> wrote in message
news:dttg1t$e5k$1$(E-Mail Removed)...
> Andrew Hodgson <(E-Mail Removed)> wrote:
> >
> >These DSL modems through ethernet are a bit of a hole - they are
> >basicly routers but that are set up in such a way that it will turn
> >off NAT by default and assign via DHCP the IP address of the WAN
> >interface. You could buy a D-link that does this - I believe Linksys
> >also do one, or you could buy a cheap Conexant based router (such as
> >the Safecom SAMR4112, which whilst acts like a router by default, can
> >be changed to bridging mode very easily.
> >
>
> Ah, that makes sense... but if it (the DSL-300G+ ethernet modem,
> I mean) was a sort of 'straight-through' router, wouldn't it appear
> in the traceroute? It does have its own address too - 192.168.0.1 -
> with a web and telnet interface on it for setting it up, but traceroutes
> show the first hop as the ISPs routers. Perhaps 'bridging mode'
> is the important point that I'm missing here!
>
> As you can tell, I really should learn more about IP networking!
> Anyone know any good books? Teach Yourself IP in 5 minutes?
>
> dom.
>

On Sun, 26 Feb 2006 19:58:47 +0000, Andrew Hodgson wrote:

> These DSL modems through ethernet are a bit of a hole - they are basicly
> routers but that are set up in such a way that it will turn off NAT by
> default and assign via DHCP the IP address of the WAN interface.

I've been looking into this a bit, because I don't like USB PPPoA modems,
and because I'm running into trouble with my D-Link DSL-504T and
file-sharing.

From what I've read BT does support the use of PPPoE, as well as PPPoA.
It's still run over ATM, but the ppp is encapsulated in ethernet before
being sent over ATM. If you have a modem/router that can bridge PPPoE, you
can connect your modem with ethernet, and terminate PPP on your computer,
which means you are using it as a true modem.

I understand it requires the ISP to support it, and many ISP tech support
people are a bit clueless about it.

Has anyone any experience of doing this with a 504T, or with UKONLINE LLU?