Comcast Cable not working w/Linux
 

I just got cable service thru Comcast, and to my chagrin, am sending this email out in the Windows side of my dual-boot.

Background:

My linux distro is Mandrakelinux 10.1

'Was' connected (for 4 years) thru Earthlink with a DSL connection. Had two computers set up thru a switchbox. One of the boxes (this one) dual-booted (XP and the aformentioned 10.1), the second ('puter) was exclusively Linux (Mandrake) and everything worked fine (well, within Earthlink's definition of 'fine', but let's not get started on that.)

I'm connecting this box with a 3-Com ethernet connector, installed where it has always been installed (emphasizing the fact that I made NO changes to my system except going from DSL to cable).

Obviously, the (Windows) connection works fine with the new connection, as that's how I'm now communicating.

Just as obviously, or I wouldn't be here complaining now, my linux side will not connect.

Start with this premise-I have not a clue what I am doing. I did go to the GUI screen (in my Mandrake distro) and, as su, attempted to set up a new internet connection, using the 'cable' option and the eth1 connection, which is where my 3-com connector draws breath (eth0 is the mobo connection, and has always 'FAILED'<superseded by the 3-com> on boot-up).

Below is a display of the results of running '/sbin/ifconfig':

eth0:

Link encap:Ethernet Hwaddr 00:50:8D:ED:9A:4A
inet6 addr: fe80::250:8dff:feed:9a4a/64 Scope:Link
UP BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:35 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes: (0.0 b) TX bytes:1338 (1.3 Kb)
Interrupt:5 Base address:0xb000

eth1

Link encap:Ethernet HWaddr 00:04:75:AE:B0:9D
inet6 addr: fe80::204:75ff:feae:b09d/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:10068 errors:0 dropped:0 overrusn:235 frame:0
TX packets:12 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:610428 (596.1 Kb) TX bytes:2490 (2.4 Kb)
Interrupt:10 Base address:0xa000

lo

Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:1072 errors:0 dropped:0 overruns:0 frame:0
TX packets:1072 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:86854 (84.8 Kb) TX bytes:86854 (84.8 Kb)

Thanks in advance for your valuable input, folks.

What does /sbin/dhclient eth0 output?

A bit confused on above but is this machine have both XP and Mandrake?
This is the only machine you are connecting with?
And is the nic being used the same for both OSes?

Not knowing what you are doing with both nics I would disable the one you are not using at the moment and only get the one left working for both.

Next post info on the nics from the output of /sbin/lspci -v and which one is which. Plus the loaded modules for the nics in question.

But for starters disable the 2nd nic first. Really only one nic under linux can be configured with a Gateway. If both are trying to get and IP then they try to have thier own Gateway.

Brian

Thanks for getting back to me. I'm gonna have to sit on this until I get home from work later this evening. Just finished doing taxes, and I'm falling asleep on the keyboard-gotta be back up in 3 hours to head back out for work. I'll get back to you...

(Oh, BTW...can't find a file named '/sbin/Ispci', or such a file name in ANY directory. Also, when I run '/sbin/dhclient eth0', I cannot seem to redirect to either a text file or a printer-whether I run as 'myself' or as root. The last line informs me that there was 'no stdin, so there is nothing to redirect' (or words to that effect). Can you coach me along on this dilemma?)

LT

earth link uses pppoe your new line doesn't that is your problem. But not sure a static connection not a dynamic. you need to know. the pppoe program is sending out the wrong info. configure your card and try a static.If comcast is using a pppoe reconfigure with there gateway. If it is a pppoe their gateway is a html web page. you must use it to reconfigure your account.

Cool stuff, man! Thanks. When I get back in this evening I will print out your comments and call Comcast with that info on my desk, and hopefully they can provide the info/handholding that I need.

Thanks again.

LT

Good luck with that. I've got Comcast and in my experience, as soon as the word "linux" gets mentioned, the "service tech" has a nervous breakdown, starts speaking in tongues and on the rare occasions engages in goat sacrifice to ward off the evil Linux spirits. To put it bluntly, they don't know jack about Linux.

Comcast should issue an IP address to a standard DHCP request from a Linux client like dhcpcd, dhclient or ifup. I've never used Mandrake so I don't know which one it uses, but if you set up your Linux side to use DHCP, Comcast should respond. Now with that said, I've suspected that Comcast monitors the MAC address connected to the IP, so if you're connecting with different cards, it might cause a bit of an issue.

To be honest, if you've got more than one computer in the house, investing in a router might be the way to go. I've been connecting that way for years, and Comcast has worked fine with a couple of different brands of router (mostly Linksys).

To expand on Hangdog42's post typically cable ISPs only provide one dynamic IP address for home service. The modem stores the MAC address in memory so no other computer will be able to acquire an IP address unless modem power is recycled. In addition, using a router instead of a switch will add an extra measure of security since your home network is now isolated from the rest of the internet if you sharing files and printers via SMB.

That's a lower case L not a capital I, LSPCI = List the PCI bus contents. I don't know that I have ever run across a command in Linux that uses capital letters in the command itself..


/sbin/lspci

Comcast uses standard IPv4 DHCP addressing, no PPPoE, and Linux works just fine on their service (I've used it myself).

The only thing I've noticed is that you have IPv6 enabled. . .try removing support for that, see what happens. It probably won't do anything, but it's a thought.

Like someone else mentioned, though; get a router. It'll alleviate these problem and you'll be a little more protected.

Next...?
 

I went back over into linux and tried to reset a cable connection in the GUI screen (as root). Chose a cable connection, which automatically informed me it was setting up a "Automatic IP (BOOTPDHCP) connection. That did no good. Results the same. Nadda.

Arc1450...I don't understand what you meant by '...you have IPv6 enabled...' I can't find that reference in the detail readout that I offered. What am I missing?

IPv4: inet addr:127.0.0.1 Mask:255.0.0.0
IPv6: inet6 addr: ::1/128 Scope:Host

They're 2 different addressing schemes for your computer, and they don't always operate well together. There should be something in your TCP/IP settings that should allude to having that enabled. Disable it, and see what gives.

An offer...
 

I emailed you earlier, but I've got no faith in anything about this Comcast right now. You're a half-hour south of me thru the tunnel. Wanna make a few bucks on this dreary Saturday? (I CAN receive email, but not a lot else functions.)

I don't think you're going back far enough.

1) Unplug your cable modem
2) Plug your Linux computer (with the power off) into the cable modem
3) Power up the cable modem and let it run through its setup
4) Turn on your Linux computer and let it boot

If your Linux box is set to use DHCP, it should be able to grab an IP from Comcast.

Oh, and I don't think that IPv6 is an issue since Comcast isn't using it.

The issue isn't that necessarily IPv6 is the issue, it's that some distros I've run across only have IPv6 enabled by default. *shrug*

Either way, they're not compatible, and since Comcast isn't using it (as you said), might as well take it out of the equation. :)

South> Yeah, I tried emailing you back, but the mailer daemon for gmail doesn't seem to like your email address. :-P Unfortunately, I gotta decline unless you want to take a chance on getting as sick as me. :(

Nope. Nadda.