[aclug-L] Re: ADSL, SWBell & Linux

[Steven Saner <ssaner@xxxxxxxxxxxxxxx>]

Well, there are several things. While ADSL is different than cable
modems in that you aren't sharing bandwidth with your neighbors, it is
very possible that you will be on the same bridge with other people at
the provider. Therefore, in many ways you are on the same Ethernet as
other ADSL customers. This might mean that you have to be a bit
careful how your Windows box are configured if you have drives or
printers shared. All broadcast traffic on the bridge will get you your
machine, so there might be various types of denial of service attack
issues. I would certainly want to set up some firewalling. Now the
above issues probably aren't going to be as big of an issue for a
dedicated customer because they will probably be on a separate bridge
group, but for the average dynamic ip user, it could be an issue.

Another thing is that the service provider could give you a single
dynamically assigned IP address. However, the ADSL modem is not
limited to one computer. You could put a hub on the modem and connect
more than one computer. There are ways that the provider can filter
based on Ethernet MAC addresses to prevent this, but if they aren't
careful, customers could as least use more service than they are
paying for, and at worst could cause a denial of service against other
customers.

Granted, I am thinking of security more from a service provider's
perspective than a user's, but anytime you have people that you don't
know and trust on the same Ethernet, you have a potential for problems
unless you are very careful.


On Sun, Jan 30, 2000 at 02:11:16PM -0600, Dale W Hodge wrote:
> 
> > There are reasons other than IP space to go with PPPOE. The primary
> > one is security. There are some fairly interesting security issues
> > that come up with the bridged service. However, PPPOE is somewhat more
> > complex to implement from the ISP side. Do you know what kind of
> > equipment your provider is using to provision the service?
> >
> 
> Would you care to elaborate on the security issues?  My understanding was
> that since DSL is a point-to-point link, short of physically stealing the
> line, only the home that is connected to DSL could use the link. The only
> problems I can see, is that the link is indifferent to *who* on the other
> end of the link was using it; whereas with PPPOE, a user must first be able
> to log in before any data can be sent.
> 
> As for the equipment, they went with PulseCom (www.pulse.com). I'm not
> exactly sure of the model of thier central office equipment, but my 'modem'
> is an ADSL-8000. I'm fairly sure this link
> http://www.pulse.com/products/wavepacer/bbsyscomp.htm will get you to the
> specifics of what they are using.
> 
> --dwh
> 
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