Comcast IP Change - Internet down

Comcast IP Change - Internet down

Post by markdmcnal » Sun, 05 Oct 2003 03:52:38

After a year of always getting the same ip address, the ip address of
my linux box connected to the cable modem was changed a couple of days
ago. No problem I though except that I'm unable to see past the
gateway and nobody can see me. I'm disconnected from the Internet.
Each refresh of my ethernet port still renders the new but somehow
invalid ip address.

Very strange is that if I connect a windows box (usually resides
behind my linux firewall/router) to the cable modem, I can connect to
the Internet just fine. I however gets assigned a different ip
address (with a different gateway) from my Linux box.

My Linux box has handled ip address changes before without a hitch so
I want to believe that something is messed with the network
configuration that comcast is feeding my linux box.

I've checked my routing tables. They look fine. I can ping the
gateway but I cannot reach the DNS servers (listed in
/etc/resolv.conf) and I cannot ping any other ip address (that I know
of) that are beyond the gateway.

I read somewhere that asking comcast to reassign an ip address is a
good way to solve this. But I'm wondering if I've overlooked

Comcast IP Change - Internet down

Post by Bit Twiste » Sun, 05 Oct 2003 04:38:13

Please read ~esr/faqs/smart-questions.html

It always helps if you provide some basic system information and what
you are having problems with when you post questions to the
news groups.

That info helps us to provide better examples/responses.

Which window manager/desktop environment,
they have different icons and file access locations.

There are several "linuxes": Red Hat, Slackware, SuSE, Debian, Mandrake,
Caldera, Corel, Yellow Lab, Black Lab, WinLinux, PhatLinux, Linux On A
Floppy, slinux, Trinux, Peanut and
(Rock, Armed, Stampede, Tiny. Power, Coyote) Linux, to name a few.

Always provide what distro and release level you are using
when you post questions (Redhat 6.1, Suse 5.0, Mandrake 8.2,...).

Different distros have different commands, files, and links to files,
pacakges and package/software managers.
Even happens between release levels of the same distribution.

Internet connection problem (ISP, cable, adsl, PPPoE, LAN, dialup, eth0. USB..)

If dhcp, which client (pump, dhcpcd, dhclient,...)

Firewall (Bastille, Tiny, Smoothwall ..) , which type ipchains, iptables,...

Window manger, application problem/question give the name
(gnome, kde, sawmill, kscd, kmix, eroaster, ...) Different
window managers can have different programs.

Give us error messages if you have them.
Look in your logs, /var/log/messages on Redhat and Mandrake.

Example: Using RH 7.3, kde, dhcpcd though a cable modem on RR in Fortworth Tx.
ipchains Tinyfirewall is disabled. Still cannot get a lease.

Get to the command line on the windows box and do a
ipconfig /all or if using dhcp on Mandrake,
cat /etc/dhcpc/
and check the following for valid numbers.

Do do a ipconfig /release on the win box, power reset the modem then
do a service network restart on the linux box.


Comcast IP Change - Internet down

Post by Dan Cottle » Mon, 06 Oct 2003 00:39:56

In article < XXXX@XXXXX.COM >,

Comcast isn't doing a very good job of maintaining their routing tables.
What you've described happens now and then.

The solution is usually to fully release your lease, then get a new one,
with a new IP.

Of course. The PC is reporting a different MAC to the DHCP server.

99% of the script-readers you can reach when you call Comcast will
insist they cannot issue you another ip. And when you say *nix, their
eyes will glaze over.

Just get yourself a new ip.

- Dan.
- Psychoceramic Emeritus
- South Jersey, USA, Earth

Comcast IP Change - Internet down

Post by markdmcnal » Wed, 08 Oct 2003 02:46:52

I tried this approach and as you predicted (below), they told me they
couldn't issue me a new IP address. What they suggested is that I
release the IP and wait up to four days for my MAC to be discarded
from their "tables". Getting a new lease thereafter should then solve
my problem.

I'm not sure if I stumbled across a solution or if coincidentally
comcast solved their problem or what exactly happened. I decided to
try passing my hostname in the dhcp request (-h option using dhcpcd)
which resulted in my acquiring a new IP address (and a new gateway) -
by all appearances, I'm on a completely different subnet now. The
main thing is that my box is connected.