[lug] tcpdump, routing, ppp, and cable modem questions(s)

[Chip Atkinson]

Hmmm... thanks.  I know my modem has two IP addresses, a LAN and a WAN.
That may be the configuration out of the box but not necessarily the
correct one.  Maybe that's why I have to run the setup software that they
provide...

 On Mon, 15 Mar 2004, John Hernandez wrote:

> Chip, AFAIK, those modems are usually set up in bridging mode, which
> means your PC will need to send out the DHCP request.  As I recall, it
> also required you to send a hostname along with the request.  I'm not
> sure if that is still the case, as my connection was on the old ATTBI
> network.
>
> Chip Atkinson wrote:
>
> >Dang.  Ok.  I'll have to see if I can round up a windows machine for a
> >little while.
> >
> >About the DHCP, that is on the cable end of the modem, so I shouldn't have
> >to worry about that, right?
> >
> >Thanks for the information too.
> >
> >Chip
> >
> >On Mon, 15 Mar 2004, Ferdinand Schmid wrote:
> >
> >
> >
> >>Chip:
> >>
> >>You will need to use Internet Explorer to get to the registration site for
> >>Comcast.  I have gone through this exercise and found that they really require
> >>IE.  Also - dhcp in their cable modems doesn't necessarily work with every
> >>computer.  I had a terrible time with it on my PC - couldn't get it to work on
> >>a Dell laptop under Linux or Windows.  However, a D-Link router was able to
> >>talk to it.  Strange...  So my approach to get it working was to use a USB
> >>cable combined with a Windows PC to do the modem registration.  Until this is
> >>complete you will only be able to get to your cable modem and to Comcast's DNS
> >>servers.
> >>
> >>So - find a Windows PC to register the modem and then connect your Linux
> >>system.  If you can't get dhcp working with your particular modem then just
> >>pick your IP address manually.  The default route (your cable modem's local
> >>IP) never changes anyway.
> >>
> >>Ferdinand
> >>
> >>--On Monday, March 15, 2004 08:25:44 AM -0700 Chip Atkinson <chip at rmpg.org>
> >>wrote:
> >>
> >>
> >>
> >>>Greetings all,
> >>>
> >>>I recently signed up for internet access through Comcast, the cable TV
> >>>provider and am trying to get my machine connected to it.  During the
> >>>process I came across/caused a couple problems and also can't connect out
> >>>to anything past the cable modem.
> >>>
> >>>Here are the problems:
> >>>1) the ppp0 interface has disappeared.  It was working that morning but
> >>>now is gone.
> >>>Using kppp I get an error saying
> >>>ppp: no such interface (don't remember the exact wording)
> >>>and
> >>>ifconfig ppp0 up
> >>>returns ppp0: unknown interface: No such device.
> >>>
> >>>2) I was using tcpdump to watch network traffic on eth0.  When there was
> >>>no default route set, I saw tons of ARP requests from other machines, but
> >>>when I set the default route: route add default gw 192.168.100.1 (the
> >>>cable modem's IP), the ARP request traffic wasn't visible suddenly.  When
> >>>I deleted the default route, the traffic was visible again.
> >>>I thought tcpdump grabbed all of the traffic, regardless of routing
> >>>tables.
> >>>
> >>>3) I'm unable to get to a web server on the Comcast network to register
> >>>and get to the internet and I fear that it's due to something weird that
> >>>also caused ppp and the weird tcpdump behavior.  I can ping the WAN end of
> >>>the cable modem, but nothing else.
> >>>
> >>>Does anyone have any similar experiences or ideas?  Right now I'm kind of
> >>>stumped.
> >>>
> >>>Thanks in advance.
> >>>
> >>>Chip
> >>>
> >>>_______________________________________________
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> >>>
> >>>
> >>
> >>--
> >>Ferdinand Schmid
> >>Architectural Energy Corporation
> >>Celebrating over 20 Years of Improving Building Energy Performance
> >>http://www.archenergy.com
> >>
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> >>
> >>
> >>
> >
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