Re: [Sheflug] after a cable modem which supports SIP

["Wonkey Donkey" <wonkey_donkey@xxxxxxxxxxxxxxxx>]

----- Original Message ----- 
From: "Robin Wood" <robin@xxxxxxxxxxxxxxxxxxxxx>
To: <sheflug@xxxxxxxxxxxxxx>
Sent: Thursday, March 01, 2007 11:16 PM
Subject: Re: [Sheflug] after a cable modem which supports SIP


> On Wed, 2007-02-28 at 21:59 +0000, Chris J wrote:
>> Robin Wood wrote:
>> > Hi
>> > I'm moving to a house which has cable so I'm going to be needing a 
>> > cable
>> > modem. Can anyone recommend one which will support SIP? Even better
>> > would be one which will take openWRT (I assume that openWRT will 
>> > support
>> > SIP).
>>
>> As others have pointed out, Virgin (formally Telewest/NTL) supply a
>> router for you, however it simply acts as a network bridge. You can do
>> some poking about them - they're a Motorola Surfboard (or at least the
>> one I have is) - whether they've changed supplier in the past few years
>> I'm not sure.
>>
>> The configuration on the CM is minimal; there is (or at least was last
>> time I checked) some horrendously simply filtering supplied in the
>> configuration that blocked ports 135-139 (Windows SMB), but not much
>> else. You can't change the configuration of the box as its managed
>> centrally by Virgin. You can however use SNMP tools on it to grab
>> traffic stats to drive tools such as MRTG :-)
>>
>
> Are you saying that Virgin connect to the box to make changes? There has
> to be security issues with that, they connect and make changes without
> you knowing, they could open anything, or close something to stop you
> doing stuff.
>
> Robin
>>

Virgin/Telewest/Blueyonder dont connect directly as such. They send a modem 
capabilities settings file to the cable modem each time it is rebooted, 
which sets the connection speed etc. Thats all done through TFTP 
automatically. In the early days it was possible to setup a local TFTP 
server and in doing so change the settings to what you like, but the cable 
companies (including Blueyonder) caught onto this very quickly and changed 
things. It is also illegal for the end user to do this, because it breaches 
one of the telecommunications acts or something like that.

I know they dont block any ports at the head end; I can still use ports 
135-139 through my Motorola Surfboard CM, but not sure about the newer kit 
they supply.

The Surfboard CM's have a reasonable interface at htp://192.168.100.1, but 
again, I dont know if this is still the case for the newer kit, as they are 
from a different manufacturer.

I remember some time ago you could buy an internal PCI cable modem, which 
worked on the Telewest network, and was far superior to the external 
Surfboard ones they supplied at the time, but the details of it escape me 
right now.

Steve 



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